Download Mexico Farmed Whiteleg Shrimp Seafood Watch Report

Seafood Watch
Seafood Report
Farmed Pacific White Shrimp
Litopenaeus vannamei
© Scandinavian Fishing Yearbook/www.scandfish.com
Mexico
Final Report
January 7, 2010
Peter Bridson
Aquaculture Research Manager
Monterey Bay Aquarium
and
Irene Tetreault Miranda, Ph.D.
Independent Contractor
About Seafood Watch® and the Seafood Reports
Monterey Bay Aquarium’s Seafood Watch® program evaluates the ecological sustainability of
wild-caught and farmed seafood commonly found in the United States marketplace. Seafood
Watch® defines sustainable seafood as originating from sources, whether wild-caught or farmed,
which can maintain or increase production in the long-term without jeopardizing the structure or
function of affected ecosystems. Seafood Watch® makes its science-based recommendations
available to the public in the form of regional pocket guides that can be downloaded from the
Internet (seafoodwatch.org) or obtained from the Seafood Watch® program by emailing
[email protected]. The program’s goals are to raise awareness of important ocean
conservation issues and empower seafood consumers and businesses to make choices for healthy
oceans.
Each sustainability recommendation on the regional pocket guides is supported by a Seafood
Report. Each report synthesizes and analyzes the most current ecological, fisheries and
ecosystem science on a species, then evaluates this information against the program’s
conservation ethic to arrive at a recommendation of “Best Choices,” “Good Alternatives,” or
“Avoid.” The detailed evaluation methodology is available upon request. In producing the
Seafood Reports, Seafood Watch® seeks out research published in academic, peer-reviewed
journals whenever possible. Other sources of information include government technical
publications, fishery management plans and supporting documents, and other scientific reviews
of ecological sustainability. Seafood Watch® Fisheries Research Analysts also communicate
regularly with ecologists, fisheries and aquaculture scientists, and members of industry and
conservation organizations when evaluating fisheries and aquaculture practices. Capture fisheries
and aquaculture practices are highly dynamic; as the scientific information on each species
changes, Seafood Watch’s sustainability recommendations and the underlying Seafood Reports
will be updated to reflect these changes.
Parties interested in capture fisheries, aquaculture practices and the sustainability of ocean
ecosystems are welcome to use Seafood Reports in any way they find useful. For more
information about Seafood Watch® and Seafood Reports, please contact the Seafood Watch®
program at Monterey Bay Aquarium by calling (831) 647-6873 or emailing
[email protected].
Disclaimer
Seafood Watch® strives to have all Seafood Reports reviewed for accuracy and completeness by external scientists with expertise in ecology, fisheries science and aquaculture. Scientific review, however, does not constitute an endorsement of the Seafood Watch® program or its recommendations on the part of the reviewing scientists. Seafood Watch® is solely responsible for the conclusions reached in this report. Seafood Watch® and Seafood Reports are made possible through a grant from the David and Lucile Packard Foundation. 2
Table of Contents
I.
II.
III.
IV.
V.
VI.
Executive Summary……………………………………………………………… 4
Introduction………………………………………………………………............. 8
Analysis of Seafood Watch® Sustainability Criteria for Wild-caught Species
Criterion 1: Use of Marine Resources………………………………………… 22
Criterion 2: Risk of Escaped Fish to Wild Stocks…………………………….. 28
Criterion 3: Risk of Disease and Parasite Transfer to Wild Stocks…………… 32
Criterion 4: Risk of Pollution and Habitat Effects…………………………….. 42
Criterion 5: Effectiveness of the Management Regime……………………….. 56
Overall Recommendation and Seafood Evaluation……………………................. 60
References………………………………………………………………………… 62
Appendices………………………………………………………………………... 69
3
I. Executive Summary
Mexico supports a major shrimp farming industry and produced 114,000 tons of farmed shrimp
from 66,000 hectares of ponds in 2007. Ninety percent of this production came from two
northwestern states bordering the Gulf of California: Sonora and Sinaloa. Production is exclusive
to the Pacific white shrimp, Litopenaeus vannamei, and is rapidly increasing. For example, both
the quantity of shrimp produced in Sonora has more than doubled in the five-year period from
2003 to 2008 and the total pond area has nearly doubled in the same time. Data from 2008 show
that Sonora alone now produces over 80,000 tons from 22,000 hectares of ponds. In keeping with
the dominance of these two states (especially Sonora) and their significance among U.S. imports,
this report focuses only on production in Sonora and Sinaloa.
The Gulf of California coastal environment hosts a unique set of habitats and is considered to be
an environment of high conservation status. The great majority of Mexican shrimp farms interact
directly with this environment. Tropical mangrove forests are found in the lower two-thirds of
the gulf, while a variety of intertidal habitats exist throughout the Gulf. The interaction of shrimp
farms with these habitats, particularly mangrove forests, has been the subject of considerable
controversy on a global scale.
While the bulk of Mexican shrimp production occurs in Sonora, the greatest shrimp pond
coverage in terms of area is in Sinaloa and Nayarit to the south, where more extensive wetlands
and mangrove forest occur. A number of protected RAMSAR wetlands sites are located in
Sinaloa. Although 95% of the Gulf of California’s mangrove-associated lagoons have been
developed for shrimp farming, there is little documentation regarding the possible impacts of the
construction of these farms.
Despite the fact that relatively few mangrove-forested areas have actually been cleared for
ponds, most ponds have destroyed or impacted adjacent wetlands and tidal/salt marsh habitats,
and many (perhaps most) farms drain directly into mangrove lagoons. The tidal marsh habitats of
the Gulf are threatened wetlands that contain a diversity of plant and animal life, much of it
unique and endemic to the local habitat. It is well known from studies around the world that
shrimp farm operations can have many negative impacts on mangrove forests and other sensitive
habitats, particularly due to pond effluent. Considering the proximity of most Mexican shrimp
farms to sensitive coastal habitats and the rapid expansion in total pond area, the risks to habitats
are considered a high conservation concern.
Effluent from shrimp farms has the potential to negatively impact the environment at local and
regional scales due to nitrification, sedimentation and changes in hydrology. With daily pond
water exchanges of 10–30% or more, even though the concentration of pollutants in the effluent
water is likely to be low, the volume of effluent discharge is high, and the system is considered
to be open in this respect. The level of nutrients being discharged untreated from shrimp farms
into the Gulf of California is substantial, estimated to be equivalent (in terms of nitrogen and
phosphorous discharge) to the untreated sewage from 1.7 and 1.9 million people per year,
respectively. Researchers who have measured shrimp farm outputs suggest that the large volume
of discharged nutrients and sediment is having negative local effects, particularly on Mexico’s
“esteros” or estuaries. Effluent from shrimp farms can also contribute to the regional problems
4
associated with increasing nutrient input to the greater Gulf of California. Nutrient input to this
semi-enclosed sea has been generally increasing and is associated with various environmental
concerns including Harmful Algal Blooms (HABs). Agriculture and other anthropological
nutrient inputs to the Gulf of California are substantial, and the significant nutrient discharges
from Mexican shrimp farms further contribute to these regional impacts. Nevertheless, it appears
that Mexican shrimp farming is a relatively minor contributor to regional impacts when
compared to agriculture and other anthropological sources. The growing number of shrimp farms
has the potential to contribute more strongly to regional impacts. The pollution effects of shrimp
farming are therefore considered to be local, even though they also contribute to the larger gulfwide problem of agricultural and anthropological pollution.
Overall, discharge of untreated effluent via daily water exchanges, local impacts, and pond siting
in areas of ecological sensitivity, in addition to the continued expansion of shrimp farms into
sensitive coastal, wetland, and estuarine habitats, creates a high conservation concern for
pollution and habitat effects.
Due to the daily water exchanges and therefore the ‘openness’ of the production system, and
despite good management and biosecurity protocols, a risk of escapes exists and loss of stock is
probably inevitable. Although the majority of escapes may be small trickle losses, the failure of
key components such as outlet screens and filters, or catastrophic events such as dyke failures or
flooding, do allow significant numbers of farmed shrimp to escape. Anecdotal evidence suggests
that trawl fisherman regularly catch farmed white shrimp, but in general the frequency of escapes
is unknown.
After many generations of domestication and selective breeding for desirable traits such as
increased growth rate and disease tolerance, farmed shrimp in Mexico display significantly
different biological characteristics from wild shrimp and are likely to be ecologically distinct
from wild populations. Although there is little evidence for negative interactions or genetic
introgression, these risks exist on theoretical grounds. There is no evidence of spawning
disruption of wild shrimp by farmed shrimp, but competition for resources between wild and
escaped farmed shrimp is possible on theoretical grounds, particularly due to the proximity of
shrimp farms to typical shrimp nursery habitats. The stock status of wild penaeid shrimp in the
Mexican Pacific and Gulf of Mexico is considered poor, and the population therefore has an
increased vulnerability to disturbance. Overall, the risk of escaping farmed shrimp to wild stocks
is considered moderate.
The use of wild fishery resources for shrimp feed is considered a moderate concern for Mexico.
The calculated conversion ratio of wild fish into farmed shrimp is 1.7:1 based on the moderate
use of fish meal. In addition, farms use only hatchery and farm raised broodstock and postlarvae,
which limits the depletion of marine resources.
Evidence of direct impacts on wild shrimp populations from the amplification, retransmission or
introduction of pathogens is inherently difficult to detect, but there have been widespread
catastrophic disease outbreaks at shrimp farms. Due to the severe disease problems suffered by
the developing shrimp farming industry in Mexico, many significant steps have been taken to
reduce the likelihood of outbreaks and economic losses on farms. While reductions in disease are
5
clearly beneficial for all concerned, it is not clear how far these measures go toward protecting
wild shrimp populations.
Mexico is to be congratulated on the establishment of its state-specific aquaculture health
committees (e.g.,Comité Sanidad Acuícola del Estado de Sonora, AC) and the public availability
of production and disease monitoring data. The results of routine monitoring in Mexico’s 46
hatcheries of broodstock and postlarvae for six major shrimp diseases show that all postlarvae
produced in Mexican hatcheries and stocked into ponds are Specific Pathogen Free (SPF).
Therefore, the continued outbreaks of highly virulent shrimp diseases that occur in Mexican
shrimp ponds during the grow-out cycle clearly demonstrate that disease amplification of
endemic pathogens is occurring. In 2008, one in four farms in Sonora had an outbreak of the
viral White Spot disease, and one in three farms suffered necrotising hepatopancreatitis (NHP).
Although direct evidence is scarce, given the daily water exchanges with the outside
environment and the widespread transfer of diseases within farms, the potential for disease
transfer to wild stocks seems high, especially considering the often close proximity of farms to
wild shrimp nursery areas. Overall, the evidence of virulent disease amplification within farms,
the open nature of the production systems, and the vulnerable state of wild stocks results in a
high concern for the risk of disease and parasite transfer to wild stocks.
In addition to the aquaculture health committees, Mexico has a comprehensive regulatory
structure, which is particularly pronounced in the state of Sonora. The Law of Sustainable
Fisheries and Aquaculture was established in 2007. Under the Ministry of Agriculture
(SAGARPA), the National Commission of Aquaculture and Fisheries (CONAPESCA) deals
mostly with operating permits and the National Service of Alimentary Health, Quality and
Innocuity (SENASICA) is in charge of animal health and is responsible for the establishment of
the various committees within Comité Sanidad Acuícola del Estado de Sonora, AC (COSAES).
The dominant producing state of Sonora also has its own Law of Fishing and Aquaculture,
Sanitary Protocol, and a Best Practice scheme. The regulatory structure for aquaculture in
Mexico appears robust. The creation of COSAES to improve disease management is
encouraging and somewhat unique in the industry. However, continuing disease outbreaks on
farms and the open nature of the ponds leaves wild stocks at risk for retransmission of disease. In
addition, despite the continuing and increasing water quality problems present in the Gulf of
California (e.g., Harmful Algal Blooms), untreated effluent is still being discharged from shrimp
farms, and this issue has not yet been adequately addressed. These factors suggest a moderate
conservation concern for management effectiveness.
Due to the concerns highlighted above regarding the lack of effluent treatment, the potential for
disease transfer and impacts to sensitive habitats, the overall Seafood Watch ranking for Mexican
farmed shrimp is “Avoid”.
There do not appear to be any Mexican shrimp farms currently approved by independent
certification schemes such as the Global Aquaculture Alliance’s Best Management Practice
standards, GlobalGAP, Organic, the Better Aquaculture Practices (BAP) program in Mexico,
MéxicoGAP, or any other widely recognized scheme that might help identify better practices
among Mexican shrimp producers. It also appears that the “Mexico Calidad Suprema” label has
not been benchmarked using BAP or GlobalGAP standards for shrimp farms.
6
Effluent treatment would be a key improvement to the industry in Mexico to help mitigate the
risk of disease retransmission to wild stocks and, particularly, to reduce the amount of nutrients
and sediment being discharged to coastal and estuarine waters via high daily water exchange
rates. Researchers consistently report that nutrient inputs to the Gulf of California are causing
increasing environmental damage. The Center for the Study of Nutrition and Growth (CIAD)
recommends the use of oxidation (settling) ponds in Mexico but notes that shrimp farmers
continue to resist this better management practice. Effluent discharge from shrimp farms
represents a point source of pollution that can be monitored and regulated. If consistent
monitoring and water quality standards were met for shrimp farm effluents, or if shrimp farmers
‘closed’ their ponds to the external environment (a management method now increasingly used
in Southeast Asia), the overall ranking could improve to “Good Alternative.”
Evaluations of farmed shrimp from other countries can be found at www.montereybayaquarium.org. Table of Sustainability Ranks
Sustainability Criteria
Conservation Concern
Moderate
High
Low
Critical
√
√
Use of Marine Resources
Risk of Escaped Fish to Wild
Stocks
Risk of Disease and Parasite
Transfer to Wild Stocks
Risk of Pollution and Habitat
Effects
Management Effectiveness
√
√
√
About the Overall Seafood Recommendation:
•
A species receives a recommendation of “Best Choice” if:
1) It has three or more green criteria and the remaining criteria are not red.
•
A species receives a recommendation of “Good Alternative” if:
1) Criteria “average” to yellow
2) There are four green criteria and one red criterion.
•
A species receives a recommendation of “Avoid” if:
1) It has a total of two or more red criteria
2) It has one or more Critical Conservation Concerns.
Overall Seafood Recommendation:
Best Choice
Good Alternative
7
Avoid
II. Introduction
Shrimp continues to be the largest single seafood commodity by value, accounting for 17 percent
of the total value of internationally traded fishery products in 2006 (FAO 2008). Global
production of all marine shrimps and prawns totaled more than 6.6 million mt in 2006, of which
farmed shrimp accounted for over 3.1 million mt (FAO 2008). In 2008, the United States
imported over half a million tons of shrimp from all countries (564,240 tons, NMFS 2009).
Mexico is the sixth largest shrimp producer globally and produced approximately 128,000 tons
of farmed shrimp in 20081. The U.S. imported approximately 40,000 tons of shrimp from
Mexico, of which approximately 25,000 mt were farmed.
Globally, the shrimp farming industry has been associated with major environmental and social
impacts. The sustained global demand for shrimp, which can no longer be met by fisheries alone,
continues to provide a strong economic incentive for shrimp farming. However, the adverse
environmental impacts resulting from the uncontrolled expansion of shrimp farming in many
coastal regions in the tropics and sub-tropics have prompted widespread criticism.
This Seafood Watch report provides background information on shrimp farming and production
in Mexico and then analyzes specific aspects of the Mexican shrimp farming industry with
respect to the five impact categories of Seafood Watch’s assessment methodology.
Biology: Pacific White Shrimp (Litopenaeus vannamei)2
The Pacific white shrimp, Litopenaeus vannamei (formerly Penaeus vannamei), is a marine
crustacean belonging to the order Decapoda, a group of crustaceans that also includes lobsters
and crabs. Shrimp are distinguished from other decapods by having the front-most section of the
abdomen about the same size as the rest of the sections (Figure 1), and by having five pairs of
abdominal appendages, or pleopods, adapted for swimming (Chase and Abbott 1980).
Although there are thousands of species of shrimp, most are not suitable for commercial harvest.
Those that are harvested are relatively large, ranging from 2–10 cm carapace length, and
aggregate in some fashion so that they are amenable to capture. Worldwide, about 40 species of
shrimp meet these criteria and are caught commercially. About ten species have been raised in
captivity; for some species, such as the Pacific white shrimp (L. vannamei), selective breeding
has resulted in domesticated breeds of shrimp.
1
Based on 2008 production figures for Sonora and Sinaloa and the estimated 90% of total Mexican shrimp
production produced in these two states in 2007 (the last year when complete data for all states are available).
2 Substantial parts of this section were taken from the Seafood Watch report “U.S. Farmed Marine Shrimp” by S. Morgan and V. Galitzini. 8
Figure 1. Basic shrimp anatomy. Figure courtesy of South Carolina Department of Natural Resources.
Most shrimps are omnivorous predators and scavengers. The intestine runs the dorsal length of
the abdomen; it is the brown line sometimes called the "mud vein" on cooked shrimp. Like other
arthropods, shrimps have no internal skeleton, being protected instead by a chitinous exoskeleton
which must be repeatedly shed as the animal grows (Chase and Abbott 1980). The sexes are
separate, and females tend to be larger than males. Some species release their eggs into the water
column, while others brood the fertilized eggs on the female's abdomen until hatching. Newly
hatched shrimp larvae bear little resemblance to adults; these larvae must undergo up to 12 molts
to reach the postlarval or juvenile stage. Pandalid shrimps, such as the spot prawn, may live for
three to seven years (Schlining 1999, Idoine 2001). In contrast, many of the warm-water penaeid
shrimps complete their life cycles in one to three years (LDWF 2000). Generally, adult penaeid
shrimps spawn in offshore waters and their eggs and larvae are transported to the coast as they
develop (Figure 2). Shrimp larvae drift with the plankton where they are important food for
many fishes and invertebrates (Chase and Abbott 1980). After a period of estuarine or coastal
residence, those that survive become adults and migrate offshore.
9
Figure 2. Diagrammatic representation of the typical penaeid shrimp life history.
Pacific white shrimp belong to the family Penaeidae. The bodies of these animals are
translucent but often have a bluish-green hue (Figure 3) due to the presence of pigmented
chromatophores (molecules evolved to collect/reflect light). Litopenaeus vannamei can reach
230 mm (9 inches) in length and is restricted to eastern Pacific waters (Figure 4) ranging
from Sonora, Mexico to Tumbes in northern Peru (Farfante and Kensley 1997). The
preferred habitat ranges from muddy bottoms of the shoreline down to depths of 72 m (235
feet) (Dore and Frimodt 1987). The anatomy (Figure 1) and life history (Figures 1 and 2) of
L. vannamei are similar to other members of the family Penaeidae.
Figure 3. Litopenaeus vannamei. Picture courtesy of Auburn University, Department of Fisheries and
Allied Aquaculturists.
Hatching occurs approximately 16 hours after fertilization. Weight at first maturity ranges
from 20 g for males to 28 g for females, and is usually obtained between six and seven
months of age. Female L. vannamei, weighing 30 to 45 g, spawn 100,000 to 250,000 eggs
approximately 0.22 mm in diameter.
10
The growth and survival of L. vannamei postlarvae are strongly dependent on temperature
and salinity. When reared at temperatures of 20, 25, 30 and 35˚C and salinities of 20, 30, 35,
40 and 50 ppt, the highest survival and growth coincide at around 28–30˚C and 33–40 ppt.
Survival of juveniles is severely compromised at low salinities and high temperatures
(Ponce-Palafox et al. 1997).
Figure 4. The native geographic range of wild Litopenaeus vannamei. Figure from FAO, adapted from
Holthuis (1980).
Shrimp Farming Methods
Production methods for shrimp farms vary widely. Inputs such as water, fertilizer, feed and fry
typically vary from pond to pond, resulting in a continuum of intensity of resource use.
Generalizations can be made by categorizing systems as extensive, semi-intensive, intensive or
super-intensive, based mainly on the density of shrimp stocking in the ponds, the nature and
quantity of feed, the rate of water exchange and whether aeration is used to increase oxygen
levels in the water (Clay 2004). These categorizations have changed with the evolution of the
industry. Classifications based on Tacon and McNeil (2004) are used here.
Mexican shrimp production is characterized by semi-intensive methods in coastal ponds using
marine or brackish water and is similar to that in other major shrimp producing countries. Semiintensive methods are thus the focus of this report. In general, according to Tacon and McNeil
(2004), semi-intensive farms usually use small to moderate-sized earthen ponds (<1–20 ha), with
moderate water exchange (pumping: 5–20% water exchange/day), intermediate shrimp stocking
densities (10–20 shrimp/m3), partial or continuous aeration (particularly during the final phase of
production), fertilization and/or supplementary complete feeding. Semi-intensive farms produce
moderate shrimp yields (typically 1,000 to 3,000 but less than 10,000 kg shrimp/ha/year). Figure
5 shows a typical shrimp farming cycle. Ponds are located both on and above the intertidal mark.
Fertilizers are used to increase the naturally occurring shrimp feed in the ponds, and
supplemental feed may also be used, though not in the same quantities as in intensive farms. The
water exchange rates of 5–20% of pond volume per day can lead to pollution and disease
11
spreading both between ponds and to the local environment. However, note that shrimp ponds in
Mexico generally have water exchange rates greater than these typical values, up to 30% per day
(see Section V. Introduction to Farmed Shrimp Production in Mexico, below).
Figure 5. A typical shrimp farming system (from FAO).
Introduction to Farmed Shrimp Production in Mexico
Shrimp farming takes place in many of Mexico’s coastal states (Figure 6) but the bulk of
production comes from the northwestern states of Sonora and Sinaloa that border the Gulf of
California (Sea of Cortez). There are a number of low-salinity shrimp farms in the north of
Mexico, but their production volumes are insignificant when compared to the pond-based
12
systems. Ninety percent of Mexican farmed shrimp came from these two states in 2007 (Juarez
2008). Although other species, particularly the blue shrimp (P. stylirostris), have been cultured
in significant volumes in Mexico in the past, present production is exclusively of L. vannamei,
which is the focus of this report.
Baja California Sonora Gulf of Baja California Mexico
Sinaloa Gulf of Nayarit California Jalisco Tamaulipas
Tabasco
Colima Figure 6. Mexican states producing shrimp in 2007 are highlighted in pink. The majority of shrimp is
produced in the states of Sonora and Sinaloa (bold). Map adapted from Camarón 2007 de Acuacultura
Estadísticas Producción de en México (Anonymous 2008).
Table 1 shows production data for 2007, the most recent year for which complete data is
available, obtained from COSAES of Mexico (see also “Import and Export Sources and
Statistics” below). Historically, Sinaloa was the first Mexican region to begin shrimp aquaculture
(Alonso-Perez et al. 2003), but Sonora now dominates production. According to Ocean Gardens
Products, Inc., a leading importer of Mexican shrimp, the primary sources of exports to the U.S.
are Sonora and northern Sinaloa (Mr. Shawn Hester, former Director of Marketing, pers. comm.,
June 2009). In 2008, Sonora had 169 registered farms, of which 134 were in active production
(COSAES 2009).
13
State
Sonora
Sinaloa
Nayarit
Colima
Baja California Sur
Tamaulipas
Baja California
Tabasco
Jalisco
Total (mean)
Pond Area
(ha)
18,208
40,866
5,088
350
612
749
122
211
262
66,468
Postlarvae
Stocked
(millions)
4,085
3,628
451
137
231
190
48
41
18
8,831
Intensity
(PL/m2)
Production
(mt)
Yield
(kg/ha)
22.4
8.9
8.9
39.1
37.6
25.4
39.3
19.4
6.9
(23.1)
68,510
33,408
4,912
1,500
3,143
2,232
292
215
105
114,317
3,763
818
965
4,286
5,136
2,980
2,393
1,019
401
(1,720)
Table 1. Marine shrimp production in Mexico in 2007 (data from COSAES 2009).
Shrimp production in Mexico continues to rapidly increase. For example, in 2008, Sonora
produced 81,311 tons of farmed shrimp, an increase of nearly 20% over the 68,510 produced in
2007, and more than double the production of 2003 (36,247 tons). Over the same period, the area
of producing ponds also nearly doubled from 11,373 hectares to 21,038 hectares. Figure 7 shows
the increase in area and production from 2003 to 2008, as well as the various changes in
postlarvae stocked and yield rates in the dominant state, Sonora.
Production intensity in terms of postlarvae per square meter and tons per hectare varies
considerably between different states as well as between farms. Thus, the average statewide
values in Table 2 should be used with caution. With a statewide range of average postlarval
stocking densities of 6.9 to 39.1 postlarvae per square meter, yields vary accordingly and range
from 400 to 5,136 kg per hectare. Based on the Tacon and McNeil (2004) system of classifying
shrimp farm production systems, the bulk of production in Mexico takes place in semi-intensive
systems.
14
90
25,000
70
20,000
60
Area (Ha)
Prod uction (1,000 tons)
80
50
40
15,000
10,000
30
20
5,000
10
0
0
2003
2004
2005
2006
2007
2008
2003
2004
2005
2006
2003
2004
2005
2006
2007
2008
4500
6,000
4000
3500
Yield (tons/Ha)
PL stocked (millions)
5,000
4,000
3,000
2,000
3000
2500
2000
1500
1000
1,000
500
0
0
2003
2004
2005
2006
2007
2008
2007
2008
Figure 7. Production figures for Sonora from 2003 to 2008 (data from COSAES 2009). PL = postlarvae.
The climatic conditions of Sonora and northern Sinaloa versus southern Sinaloa dictate whether
shrimp are farmed using one cycle of stocking and harvest or two cycles. The northern climate of
Sonora and northern Sinaloa is arid with cold winters, which shortens the production season to
one cycle, and because of high shrimp densities and high evaporation, farmers use water
exchange rates greater than 10–12% per day (Anonymous 2004). However, according to Ms.
Lorayne Meltzer (Co-Director of the Kino Bay Mexico Center and faculty member of the
Environmental Studies department at Prescott College who has been conducting field research on
Mexican shrimp farms since 2000), for the region around Bahia Kino in Sonora, typical water
exchange rates are 30% per day, with one cycle per year from April through October (pers.
comm., 5 August 2009). On the other hand, southern Sinaloa has mild winters, which allows for
two growing cycles and farmers use reduced water exchange rates averaging 4% per day (PáezOsuna et al. 1997)
According to Ocean Gardens Products, Inc., a leading importer of farmed shrimp from Mexico,
most of the imported farmed shrimp from Mexico consist of larger-sized products from farms in
Sonora and northern Sinaloa that use one cycle of stocking and harvesting (S. Hester, pers.
comm., 24 June 2009). The one-cycle method produces larger shrimp than the two-cycle method.
The “season” for one-cycle shrimp farming begins with stocking in April and ends with final
15
harvest in November. The one-cycle ponds then lie fallow from December through March and
dry out. The two-cycle farms produce smaller shrimp for domestic sale. For two-cycle farms, the
first cycle spans mid-February through May or June, then a rest of approximately 20 days
precedes the second cycle from June or July through the end of November. Two-cycle farms lie
fallow from approximately December through February.
Since the early 1990s, wild postlarvae (PL) have not been used in Mexican aquaculture. Instead,
46 hatcheries produce approximately 9 billion postlarvae per year from captive bred and
domesticated broodstock (Juarez 2008). The hatcheries are located mostly in the northwestern
states (Table 2) with the majority in Sinaloa. In 2007, 8.82 billion postlarvae were produced
(COSAES 2009). In 2009, 42 of the 46 hatcheries appeared to be in active production (COSAES
2009).
State
Sinaloa
Sonora
Nayarit
Baja Sur
Colima
Yucatan
Unknown
Total
Number of hatcheries
25
7
6
3
2
1
2
46
Table 2. Mexican hatcheries by state (COSAES 2009).
The hatcheries produce Specific Pathogen Free (SPF) postlarvae and are regularly monitored by
COSAES. Detailed results are available on the various Comite websites (see Annex II). Hatchery
production of postlarvae peaks in April and drops to zero in Sonora in September and October.
There do not appear to be any Mexican shrimp farms currently approved by independent
certification schemes such as the Global Aquaculture Alliance’s Best Management Practice
standards, GlobalGAP, Organic, the Better Aquaculture Practices (BAP) program in Mexico,
MéxicoGAP, or any other widely recognized scheme that might help identify better practices
among Mexican shrimp producers. It also appears that the “Mexico Calidad Suprema” label has
not been benchmarked using BAP or GlobalGAP standards for shrimp farms.
Availability of Science
The provision of shrimp for human consumption from both wild-capture fisheries and
aquaculture has been the focus of a large scientific and general literature. While much of the
science regarding aquaculture relates to developing production techniques in terms of nutrition,
genetic development, disease, and general biology and physiology, a significant segment of the
literature relates to various environmental impacts associated with shrimp farming.
16
The shrimp farming industry has developed rapidly on a global scale. During this time, the
literature has evolved as understanding of the many complex issues relating to shrimp
aquaculture has developed. Rapid changes in various aspects of production continue to occur, for
example, in response to changes in feed prices or major disease outbreaks. Therefore, literature
more than a few years old must be used with caution unless to demonstrate historical
developments. The shrimp farming industry has also been the focus of a large number of nonpeer reviewed publications. Again, these must be used with caution and checked against other
peer-reviewed references where necessary. Due to differing opinions and agendas among authors
both for and against the industry, it can be difficult to identify the real situation at the farm level.
Mexico is unusual in having production and disease monitoring data publically available online
(in Spanish). While these data have been generated in association with industry, they are mostly
government-sourced and are trusted as accurate for the purposes of this report.
Market Availability
Overall, shrimp continues to be the world’s most valuable seafood, representing 17% of the total
value of internationally traded fishery products in 2006 (FAO 2009). Historically, wild-caught
product provided the majority of shrimp on the market, but farms now produce 48% of the
world’s shrimp (FAO 2008). Shrimp is the preferred seafood choice in the U.S., even surpassing
tuna.
Common and market names:
There is confusion regarding the common names of shrimps and prawns. In U.S. markets,
"shrimp" is the default name for all shrimps and prawns. "Prawn" often refers to freshwater
shrimp or large saltwater shrimp. The term "scampi" refers not to a species but to a cooking
method, any large shrimp cooked in butter and garlic. Perhaps more than any other seafood
commodity, the market names of shrimp are seldom standardized. Several different species are
commonly called "white shrimp"; the situation is the same for "pink shrimp", "rock shrimp" and
"tiger shrimp" (NOAA 2001). Moreover, widely distributed species have many common names.
As an example, the circumpolar species Pandalus borealis is marketed variously as pink shrimp,
northern shrimp, Alaska pink shrimp, northern pink shrimp, Pacific pink shrimp and salad
shrimp.
Commercially harvested shrimp may be divided into three categories based on their habitat:
coldwater or northern species; warmwater, tropical, or southern species; and freshwater species.
For farmed shrimp, Litopenaeus vannamei (Pacific white shrimp or whiteleg shrimp) and
Penaeus monodon (black tiger shrimp/prawn) dominate worldwide production and are most
likely to represent farmed shrimp in the U.S. All farmed shrimp imported from Mexico are
Pacific white shrimp, L. vannamei, as are most of the wild-caught shrimp from Mexico.
Nevertheless, some wild-caught product from western Mexico includes Farfantepenaeus
californiensis (brown shrimp, camarón café) and Litopenaeus stylirostris (blue shrimp, camarón
azul).
17
Seasonal availability:
In general, the season for shrimp farming begins with stocking in April and ends with final
harvest in November (Ocean Gardens Products, Inc., S. Hester, pers. comm., 24 June 2009).
Nevertheless, according to Sergio Escutia, a shrimp farmer from the state of Sinaloa and
President of COADES (the Confederation of Aquaculture Organizations in Sinaloa, the
Confederación de Organizaciones Acuícolas del Estado de Sinaloa), shrimp farms in Mexico
cover a broad geographic range. This allows for staggered harvests and eliminates large seasonal
variations in the availability of shrimp products (Rosenberry 2008).
Product forms:
There is a great diversity in product forms (Figure 8) for shrimp on the market (Seafood
Handbook 1999). Product can be raw, cooked, fresh or frozen. The forms of primary product for
frozen shrimp are:
•
•
•
•
•
•
•
•
•
Green Headless: The standard market form. Includes the six tail segments with vein,
shell and tail fin. "Green" does not refer to shell color but to the raw state of the shrimp;
also called "shell-on" or "headless".
Peeled: Green headless shrimp without the shell.
PUD: Peeled, un-deveined, tail fin on or off; raw or cooked. The vein, running the length
of the tail, is the intestine, also called the mud vein or sand vein.
Tail-on Round: Un-deveined shrimp with tail fin on.
P&D: Peeled, deveined, tail fin on or off; raw or cooked. Another name for IQF P&D
shrimp is PDI (peeled, deveined and individually frozen).
Cleaned: Shrimp that is peeled and washed, a process that removes some or all of the
vein but is not thorough enough to warrant the P&D label.
Shell-on Cooked: Cooked tail with vein, shell and tail fin.
Split, Butterfly, Fantail: Tail-on shrimp that are cut deeply when being deveined.
Pieces: Shrimp with fewer than four or five whole segments.
Figure 8. Product forms for shrimp (Seafood Handbook 1999).
•
•
Frozen Products: Frozen shrimp generally comes in two forms: blocks (shrimp frozen en
masse) and individually quick-frozen (IQF) packs. Both shrimp blocks and IQF shrimp
are glazed with a protective ice coating to prevent dehydration.
Breaded Shrimp: Shrimp, whether tail-on or tail-off, is the most-common breaded
seafood on the market.
18
In the U.S., the various species of shrimp (whether wild-caught or farmed) are generally sold
interchangeably, traded by size rather than species. Shrimp are sold by number per pound rather
than by individual weight (Seafood Handbook 1999). For example, a 16/20 count means it takes
16–20 shrimp of that size to make up a pound, and the smaller the count, the larger the shrimp
(Table 3).
Size Name
Green headless
Peeled
Cooked
Extra Colossal
Under 10
Under 15
16/20
Colossal
Under 15
16/20
21/25
Extra jumbo
16/20
21/25
26/30
Jumbo
21/25
26/30
31/35
Extra large
26/30
31/35
36/40
Large
31/40
36/45
41/50
Medium large
36/40
41/45
46/50
Medium
41/50
46/55
51/60
Small
51/60
56/65
61/70
Extra small
61/70
66/75
71/80
Tiny
Over 70
Table 3. U.S. shrimp marketing definitions, count per pound. Source: (Seafood Handbook 1999).
The U.S. imported over 34,000 mt of wild and farmed marine shrimp from Mexico in 2008
(NMFS 2009). The dominant form of these imports (95%) was frozen green headless (shell-on)
in sizes ranging from “tiny” to “colossal”. Other product forms included frozen peeled, frozen
breaded, peeled fresh/dried/salted/brine and other unspecified preparations. According to Ocean
Gardens Products, Inc., Mexico mainly exports the larger-sized shrimp to the U.S. Some smaller
sizes are also exported, obtained from pre-season “thinning” during July and August (Ocean
Gardens Products, Inc., S. Hester, pers. comm., 24 June 2009). Information from NMFS trade
data (2009) appears to confirm this: in 2008, the largest single shrimp product imported from
Mexico was green headless 21/25 (jumbo), comprising 37% of all imported shrimp from
Mexico.
Import and export sources and statistics:
The National Marine Fisheries Service (NMFS) is the authority on fisheries products imported to
the U.S. For shrimp, NMFS does not distinguish between imports of marine or freshwater
species or whether shrimp were farmed or wild-caught. The Food and Agricultural Organization
of the United Nations (FAO), however, distinguishes between production of both farmed and
wild-caught shrimp and the species. Thus, country-specific imports of farmed marine shrimp
from Mexico to the U.S. can be estimated indirectly by multiplying total Mexican shrimp
imports to the U.S. with production of farmed marine shrimp in Mexico. Those calculations are
summarized in Table 4 for 2007 (the latest year for which both import and production data are
available). The reported Mexican production of 113,630 mt of farmed marine shrimp in 2007 by
FAO closely agrees with the estimate by COSAES (2009) shown in Table 1 (114,317 mt).
19
Total Shrimp*
Imported to U.S.
from Mexico
in 2007 (mt)
Farmed Marine
Shrimp Production
(mt) in Mexico
Reported to FAO
Wild-Caught
Shrimp Production
(mt) in Mexico
Reported to FAO
Proportion of
Production from
Farms
Estimated Farmed
Shrimp (mt) Imported
to the U.S. from
Mexico†
40,558
113,630
73,590
61%
24,616
Table 4: Shrimp imports to the U.S. and production statistics for Mexico in 2007. Data for total shrimp
imported are from NMFS; production data are from FAO. Notes: * “Total Shrimp” includes all wild caught
and farmed product of both marine and freshwater species. † Estimate based on percentage of total
production from farmed shrimp multiplied by Total Shrimp imported to U.S.
The estimates in Table 4 suggest that approximately 25,000 mt of shrimp on the U.S. market
originated from marine shrimp farms in Mexico. This estimate was verified during the interview
in 2008 with Sergio Escutia (Rosenberry 2008) who said that approximately 20% of Sinaloa
farmed shrimp production is imported to the U.S. All Mexican farmed shrimp imported to the
U.S. comes from Sonora and northern Sinaloa (Ocean Gardens Products, Inc., S. Hester, pers.
comm., June 2009) When extrapolated to both Sinaloa and Sonora, 20% of 113,630 mt is
approximately 23,000 mt (Rosenberry 2008).
20
III. Analysis of Seafood Watch® Sustainability Criteria for FarmRaised Species
According to Boyd (2003), aquaculture has become widespread enough to have significant
impacts on the environment and natural resources. The most serious concerns are the following:
(a) Destruction of mangroves, wetlands and other sensitive aquatic habitat by aquaculture
projects;
(b) Conversion of agricultural land to ponds;
(c) Water pollution resulting from pond effluents;
(d) Excessive use of drugs, antibiotics and other chemicals for aquatic animal disease
control;
(e) Inefficient utilization of fish meal and other natural resources for fish and shrimp
production;
(f) Salinization of land and water by effluents, seepage and sediment from brackish water
ponds;
(g) Excessive use of groundwater and other freshwater supplies for filling ponds;
(h) Spread of aquatic animal diseases from culture of organisms to native populations;
(i) Negative effects on biodiversity caused by escape of non-native species introduced for
aquaculture; destruction of birds and other predators, and entrainment of aquatic organisms in
pumps; and
(j) Conflicts with other resource users and disruption of nearby communities.
The Seafood Watch sustainability criteria address a similar range of impacts using five criteria:
1 – Use of marine resources
2 – Risk of escaped fish or shrimp to wild fish stocks
3 – Risk of disease transfer to wild stocks
4 – Risk of pollution and habitat effects
5 – Effectiveness of the management regime
Scope of the analysis
The great majority of Mexican farmed shrimp production occurs in the northwestern states
bordering the Gulf of California. Sonora produced more than double the quantity of the next
largest state (Sinaloa) and these two states produced 90% of Mexico’s farmed shrimp in 2007.
Almost all U.S. imports of farmed shrimp from Mexico are produced in Sonora. Therefore, this
analysis concentrates on Sonora with reference to other states where relevant. Evaluations of farmed shrimp from other countries can be found at www.montereybayaquarium.org. The Seafood Watch criteria are elaborated in more detail below, and the specific results of the
analysis are available in Annex 1.
21
Criterion 1: Use of Marine Resources
Guiding Principle: To conserve ocean resources and provide net protein gains for society,
aquaculture operations should use less wild-caught fish (in the form of fish meal and fish oil)
than they produce in the form of edible marine fish protein.
Primary Factors
• Estimated wild fish used to produce farmed shrimp. Calculated as the ratio of Wild Fish
in to Farmed Fish (shrimp) out (WI:FO)
Secondary Factors
• Stock status of the reduction fishery
• Source of stock for the farmed species
Fish meal and fish oil are important ingredients in aquaculture feeds as well as for agriculture
such as pigs and poultry. These ingredients supply the essential amino acids and fatty acids
needed for growth in many species, including shrimp. Aquaculture currently uses the largest
portion of the world’s supply of fish meal and fish oil, with predictions of even greater
dependence in the future as the aquaculture sector expands. The supply of fish meal and fish oil
usually comes from small bony forage fish (from forage fisheries or reduction fisheries). The
wild fisheries supplying fish meal and fish oil are fully exploited and face increasing pressure.
If aquaculture production of organisms requiring protein- and oil-rich diets is to reduce its
dependence on wild-caught fish and other marine resources, protein alternatives (including plantbased proteins and those derived from processing wastes) must be further developed. The use of
plant proteins and rendered animal products in fish feeds is now widespread throughout the
world (most diets for salmon have 15–30% vegetable products and 10–40% rendered animal
products); however, it is not currently possible to completely eliminate the use of fish meal and
fish oil without negatively impacting fish welfare or their nutritional profile (i.e., reducing the
concentration of beneficial omega-three fatty acids) (Tacon 2005). Formulating alternative feeds
to a specific nutrient profile is possible in the case of fish meal, but doing so has been more
problematic for fish oil, as there are no commercial alternatives at a sufficient scale of production
currently available (Tacon 2005). Although research continues into alternative feeds, using wild
fish inputs remains a major limitation for the future growth of a sustainable aquaculture industry.
To achieve true sustainability, the industry must reduce its dependence on wild fish and other
marine resources, finding a balance between the needs of fish physiology, animal welfare,
sustainability of the reduction/forage fisheries, human health needs and the preferences of the
human palate.
Potential alternatives to fish meal and fish oil include soybeans, barley, rice and peas, as well as
canola, lupine, wheat or corn gluten, algae, and by-products of seafood and agricultural
processing. The fully exploited status of forage fisheries, increasing demand, the high cost of fish
meal and fish oil, and sustainability concerns are all spurring research into alternative feed
options, particularly for the aquaculture sector. For example, the National Oceanic and
Atmospheric Administration (NOAA) partnered with the U.S. Department of Agriculture
(USDA) and launched the Alternative Feeds Initiative in November 2007 in order to accelerate
the development of alternative feeds for aquaculture (NOAA 2008).
22
Tacon and Metian (2008) reported specific information about the use of fish meal and fish oil in
the aquaculture industry. Their report comes from a 2006/7 global survey of aquaculture feed
manufacturers. This study remains the most comprehensive source of information on aquaculture
feed production to date. They estimated total shrimp feed production in Mexico between 170,000
and 210,000 tons (from a total Mexican aquaculture feed production of 200,000–250,000 tons).
Primary Factor – WI:FO
To estimate the use of marine resources, Seafood Watch calculates the ratio of wild fish inputs
needed to produce the farmed fish (shrimp) output (WI:FO). This WI:FO estimate is equivalent
to the “fish conversion efficiency” described in the report “Sustainable Marine Aquaculture:
Fulfilling the Promise; Managing the Risks” by the Marine Aquaculture Task Force (2007). The
WI:FO ratio is calculated by multiplying three separate measures:
1)
2)
3)
Yield rate – the amount of fish meal or oil extracted from whole wild fish,
Inclusion rate – the percentage of fish meal and fish oil included in formulated feeds,
(calculated separately for fish meal and fish oil), and
Feed conversion ratio (FCR) – the ratio of feed inputs to farmed fish output, most simply
calculated as the dry weight of feed divided by the wet weight of fish (shrimp)
harvested.
WI:FO = Yield rate x Inclusion rate (%) x FCR
Yield rate
Yield rates can vary depending on species of fish, season, condition of the fish and efficiency of
the reduction plants. The exact sources of fish meal and fish oil can be difficult to determine, but
Tyedmers (2000) reports yield rates for aquaculture feeds. Seafood Watch therefore uses the fish
meal and fish oil yield rates of 22% and 12%, respectively (from Gulf of Mexico menhaden),
suggested by Tyedmers (2000) as representative averages. These values mean that 4.5 units of
wild fish from reduction fisheries are needed to produce a single unit of fish meal, and 8.3 units
of wild fish are needed to produce a single unit of fish oil. Until further references are available,
Seafood Watch considers these to be the most accurate estimates for yield rates for fish meal and
fish oil in aquaculture.
Inclusion rate
Shrimp feeds typically contain moderate amounts (compared to other farmed aquatic species) of
fish meal and contain low levels of fish oil. Tacon and Metian (2008) reported inclusion rates of
fish meal and fish oil used in Mexican shrimp feeds (Table 5). In calculating WI:FO values, fish
meal is the more important value (see Summary of WI:FO Calculations, below).
23
Fish meal
Fish oil
Range and (mean*) Inclusion Rates (%)
8 – 40 (16)
1 – 4 (3)
Table 5. Inclusion rates for the shrimp farming industry in Mexico according to the survey by Tacon and
Metian (2008). Note: * The mean values reported by Tacon and Metian (2008) are used for the analyses in
this report.
Economic feed conversion rate
The economic feed conversion rate (eFCR or FCR) is generally defined as the ratio of total
feed weight used to the net production output (total weight gained by the stock) over one or
more farming cycles.
This metric can be expressed as:
Feed Weight / (Final Stock Wet Weight – Starting Wet Weight) = eFCR
Globally, compound shrimp feeds were estimated to have an eFCR of 1.7 in 2007; this is
predicted to fall to 1.4 by 2020 (Tacon and Metian 2008). However, estimating eFCR values
is challenging because the numbers depend on several factors, including size of the farmed
shrimp, farming conditions (e.g., use of feed trays, Jory et al. 2001), stocking densities,
escapes and individual survivorship. For example, large shrimp grow less efficiently than
smaller shrimp (Wyban et al. 1995) such that smaller size-class shrimp (e.g., 15 g) have
lower eFCR values than larger size classes (e.g., 30 g individuals) (Jaenike June 2007). The
use of “average” eFCR values is further complicated by the fact that individual ponds
produce shrimps of varying sizes, such that a given eFCR corresponds to a range of size
classes.
According to the survey by Tacon and Metian (2008), eFCR values for Mexican shrimp farms
range from 1.2 to 2.3, but COSAES reports the FCR range in Sonora as 2.2 to 2.4 (COSAES,
Miguel Olea, President, and Jorge Benitez, General Manager, pers. comm., June 2009). This
report considers the COSAES mean eFCR value of 2.3 as the most appropriate value (Table 6)
because most of the farmed shrimp imported from Mexico is produced in Sonora (Table 1) and it
is a conservative estimate.
Economic FCR
Range
Mean
1.2 – 2.3
1.9
2.2 – 2.4
2.3*
Source
Tacon and Metian (2008)
COSAES
Table 6. Economic FCR values reported for shrimp farms in Mexico. Note: * The mean eFCR value of 2.3
for shrimp farms in Sonora is used in this report.
24
WI:FO Calculations
Tacon and Metian (2008) provide a range of values for inclusion rates. The use of the upper and
lower values in the ranges for each parameter provided by Tacon and Metian (2008) result in a
range of possible maximum and minimum WI:FO values for fish meal and oil in Mexico.
Fish meal
The range of inclusion rates for fish meal in shrimp feeds for Mexico according to Tacon and
Metian (2008) is 8–40% (mean 16%). Allowing for the full range of reported inclusion rates (in
Tacon and Metian 2008) and the mean eFCR from COSAES, the minimum, mean and maximum
WI:FO values for fish meal are 0.8, 1.7 and 4.1, respectively. The Seafood Watch methodology
considers WI:FO values of 0.1 to 1.1 to be low (green), 1.1 to 2.0 to be moderate (yellow) and
greater than 2.0 to be high (red). Therefore, the WI:FO values calculated here for fish meal fit
within these ranges as shown below. The mean value falls within the moderate (yellow) section
(Figure 9).
WI:FO Fish meal 0.0 1.0 0.0‐1.1 = Green
2.0 1.1‐2.0 = Yellow
Low = 0.8 >2.0 = Red
Mean = 1.7 High = 4 1 Figure 9. The range of WI:FO values for farmed shrimp in Mexico using fish meal inclusion rates from
Tacon and Metian (2008).
The various WI:FO values calculated here for fish meal indicate moderate use of marine
resources.
Fish oil
Similarly for fish oil, the range of inclusion rates in shrimp feeds for Mexico, according to Tacon
and Metian (2008), is 1–4% (mean 3%). Considering the mean eFCR of 2.3 from COSAES, the
minimum, mean and maximum WI:FO values are 0.2, 0.6 and 0.8, respectively, which all fall
within the low (green) section (Figure 10).
WI:FO Fish oil 0.0 0.0‐1.1 = Green
Low Mean 1.0 2.0 1.1‐2.0 = Yellow
>2.0 = Red
High Figure 10. The range of WI:FO values (low 0.2, mean 0.6, high 0.8) for farmed shrimp in Mexico using fish oil
inclusion rates from Tacon and Metian (2008).
25
Summary of WI:FO calculations
The mean WI:FO value for fishmeal (1.7) is higher than the mean value for fish oil (0.6). Based
on a precautionary approach, the higher fish meal value therefore dictates the amount of wild fish
needed to produce a given amount of farmed shrimp in Mexico.
Although the range of values provided by Tacon and Metian (2008) means that fish meal WI:FO
values vary between 0.8 and 4.1, the average value (1.7) is in the lower-middle part of the
‘Moderate’ ranking range (0.1 to 2.0). Assuming that the calculated maximum and minimum
WI:FO values of 0.8 and 4.1 represent the sample outliers and only equate to potential extremes
of production practices in Mexico (for a WI:FO value of 4.1, fish meal inclusion would have to
be 40% and FCR would have to be 2.3), it is likely that the average WI:FO value of 1.7
represents the majority of shrimp production in Mexico.
Overall, the primary factor WI:FO for Mexican farmed shrimp (1.7) is ranked as a moderate
conservation concern.
Secondary Factor – Status of the reduction fishery
Reduction fisheries (or industrial or forage fisheries) refer to those fisheries in which the harvest
is “reduced” to fish meal and fish oil, primarily for feeds in agriculture and aquaculture. The
exact sources of fish meal and fish oil can be difficult to determine for proprietary reasons, thus
only the global outlook is discussed here. Most reduction fisheries are for small pelagic species
that mature quickly, reproduce prolifically, are low in the food chain and are preyed on by higher
trophic level animals such as piscivorous fish, seabirds and marine mammals. Most reduction
fishery species are from the families Engraulidae (anchovies) and Clupeidae (herrings, pilchards,
sprats, sardines and menhaden). Landings over the past 30 years have remained relatively stable,
ranging between 20 and 30 million mt, with a noticeable dip to under 20 million mt during the
1998 El Niño (Schipp 2008).
Forage fisheries are generally resilient to fishing pressure and environmental fluctuations but are
not immune to them. Many wild reduction fisheries throughout the world are considered fully
exploited based on the single species models used to manage them (FAO 2007). It is generally
believed that the populations of fish used in most reduction fisheries are stable (Hardy and Tacon
2002 , Huntington et al. 2004), though concerns have been raised about the potential for
increased demand from expanding industries for farmed carnivorous fish (Weber 2003) and, in
most cases, the populations are classified as fully exploited (Tacon 2005). However, the multispecies and ecosystem effects of harvesting large quantities of forage fish are rarely considered.
Forage species play a crucial role in marine ecosystems as they transfer energy from plankton to
larger fishes, seabirds and marine mammals (Naylor et al. 2000, Alder and Pauly 2006, MATF
2007). The ecosystem effects of harvesting large quantities of small pelagic species are likely to
include increases in competitor populations and declines in predator populations (Dayton et al.
2002). For example, Uphoff (2003) found that declines in the body condition of predatory striped
bass (Morone saxatilis) were correlated with declines in heavily exploited stocks of southeastern
U.S. menhaden (Brevoortia tyrannus). There is currently a call for caution from the fishery
conservation community, with requests to specifically address ecosystem effects in management
of forage fisheries (MATF 2007, NCMC 2008). The National Marine Fisheries Service has
26
recently proposed a revision to its National Standard Guidelines that considers ecological factors
in setting allowable catches for forage fisheries (Federal Register 2008). In addition, Alder et al.
(2008) argue that forage fisheries would be better utilized for direct human consumption rather
than as agriculture and aquaculture feeds. For Mexico in particular, these forage species are a
critical source of prey for nesting seabirds. The islands in the eastern Gulf of California support
virtually all of the nesting populations of some species (e.g., Heerman’s Gulls and Elegant Terns
on Isla Rasa or Blue-Footed Boobies on Isla San Pedro Martir, L. Kino Bay Mexico Center,
Meltzer, pers. comm., 31 August 2009).
Based on their status as stable but generally fully exploited, the health of the reduction fisheries
is deemed a moderate conservation concern according to Seafood Watch criteria.
Secondary factor – Source of stock
Historically, shrimp farms used to depend on the capture of brood stock and postlarvae (PL)
from the wild. By the mid-1970s, hatcheries were supplying large quantities of postlarvae shrimp
(Briggs et al. 2005). The use of wild caught postlarvae is now obsolete in many countries and an
increasing number of countries (including Mexico) have regulations that prohibit the practice.
Hatcheries often select for disease-resistant shrimp and supply Specific Pathogen Resistant
(SPR) PL, and they also supply Specific Pathogen Free (SPF) PL from domestic broodstock
raised in closed systems that are guaranteed to be free of certain diseases.
The shrimp species being farmed is an important consideration when evaluating the use of
marine resources because the source of broodstock and PL differs between L. vannamei and
Panaeus monodon. Closed life-cycle hatchery techniques are more difficult and are still being
developed for P. monodon, while that technology is readily available for L. vannamei. The result
is that the capture of wild broodstock and wild PL is more widespread for P. monodon than for L.
vannamei, leading to greater use of marine resources for P. monodon culture.
Because Mexican shrimp farms use only hatchery-raised postlarvae, this factor is rated as a low
conservation concern.
Synthesis
Despite the potential range of values suggested by Tacon and Metian’s 2008 study, the WI:FO
value of 1.7 (“moderate” use of marine resources) is considered robust. Variations around the
average values of fish meal and fish oil inclusion—along with FCR values that are realistic in
practice on Mexican shrimp farms—are unlikely to change this ranking to the high WI:FO range.
Because secondary factors are ranked moderate and low, respectively, the overall ranking for use
of marine resources is moderate. For the full analysis, see Annex 1.
Use of Marine Resources Rank:
Low
Moderate
27
High
Criterion 2: Risk of Escaped Shrimp to Wild Stocks
Guiding Principle: Sustainable aquaculture operations pose no substantial risk of deleterious
effects to wild shrimp stocks due to the escape of farmed shrimp.
Primary Factors
• Evidence that farmed shrimp regularly escape to the surrounding environment
• Status of escaping farmed shrimp to the surrounding environment
Secondary Factors
• Where escaping shrimp are non-native—evidence of the establishment of self-sustaining
feral stocks
• Where escaping shrimp are native—evidence of genetic introgression through successful
crossbreeding
• Evidence of spawning disruption of wild shrimp
• Evidence of competition with wild shrimp for limiting resources or habitats
• Stock status of affected wild shrimp
Accidental or intentional introductions of non-native species have become an alarming global
environmental problem (Leung and Dudgeon 2008). Aquaculture activities are considered one of
the major pathways for the introduction of non-native aquatic species that may become invasive
(Weigle et al. 2005, Casal 2006). Generally, Myrick (2002) described six potential negative
impacts of escaped farmed organisms: genetic impacts, disease impacts, competition, predation,
habitat alteration and colonization. Escaped farmed organisms can negatively impact the
environment and wild populations whether they are native to the area in which they are farmed
or exotic, and the probability of significant ecological impact increases as the number of escaped
individuals increases (Myrick 2002). The risk of impact to the environment from escaped farmed
organisms can be reduced through proactive measures such as careful selection of sites, species
and systems; training of personnel; and the development of contingency plans and monitoring
systems (Myrick 2002). The chances of escape depend in large part on the siting of the pond and
on the nature of the production method.
Since the early days of shrimp farming, the preferred culture species (P. monodon, L. vannamei
and P. japonicus) have been transferred away from their native habitats to farms worldwide
(Ronnback 2001). Litopenaeus vannamei, native to the Pacific coast of Latin America from
Mexico to Peru, has been farmed along the Caribbean and Atlantic coasts (including the Gulf of
Mexico) from South Carolina to Brazil, and is now widespread throughout Asia. Penaeus
monodon, native to the Indian Ocean and the southwestern Pacific Ocean from Japan to Australia
as well as Africa, has been transported throughout Asia and brought to Latin America and the
United States (Clay 2004).
A potential threat to native populations from farmed shrimp is loss of genetic variation, which
can be detrimental to a population's fitness and survival. Longtime broodstock management in
closed systems is expected to lead to reduction or even complete eradication of genetic
variability. The two main phenomena that are greatly responsible for loss of genetic variation in
small, isolated breeder populations in captive conditions are the founder effect and inbreeding.
28
The founder effect can result when a small number of broodstock are used and genetic variation
is lost simply because there is such a small genetic pool. The use of captive-raised animals to
establish subsequent broodstocks and the reduced number of breeders (usually 100 dams and 100
sires) commonly used in hatcheries can favor the loss of genetic diversity within a closed
broodstock line. Freitas et al. (2007) noted a significant genetic variation loss occurred in studied
broodstock lines and could be detected in subsequent generations of some closed lines. In animal
breeding programs, selection coupled with a narrow genetic base can cause high levels of
inbreeding to quickly occur. For example, De Lima et al. (2008) found that some L. vannamei
alleles were lost after only three generations.
Primary Factor - Evidence that farmed shrimp regularly escape to the surrounding
environment
Shrimp can escape from farms in various ways, during harvest from open ponds, during water
exchange and flooding events (Briggs et al. 2005), as well as from hatcheries and during
transport. Open-pond production inevitably leads to escapes, although the number of escapees
and the frequency of escape episodes can be reduced with routine management measures such as
screens and meshes on outflows, by situating outflows away from coastal areas and by
constructing them to withstand flooding.
According to Clay (2004) and Briggs et al. (2005), little is known about the overall impact of
escaped farmed shrimp on wild shrimp populations and biodiversity. According to Briggs et al.
(2005), the current structure of wild shrimp populations appears to reflect large-scale historical
events rather than patterns of present-day dispersal; their literature review found no evidence of
L. vannamei becoming established outside of its range. Nevertheless, a precautionary approach
still should be taken (Briggs et al. 2005).
Anecdotal evidence indicates L. vannamei has been caught in fishing nets in Thailand and P.
monodon in the U.S., though the numbers reported are not large and may have occurred soon
after a large number of shrimp escaped. Penaeus monodon, L. vannamei, P. stylirostris and P.
japonicus are all known to have escaped from U.S. culture operations (Briggs et al. 2005). There
are records of L. vannamei escaping from shrimp ponds in the U.S., but a total of only 11 events
have been recorded in government invasive species databases since 1990 (Perry 2009). Panaeus
monodon has been officially recorded 27 times in the U.S. and is believed to have come from
animals that escaped from farms in the Caribbean (Fuller 2009). Farmed P. japonicus and P.
merguiensis have escaped facilities in the Pacific Islands, with the latter now known to be
established off Fiji (Briggs et al. 2005). There is a P. monodon fishery off of the western coast of
Africa that has been attributed to farmed escapes.
In the wild shrimp fisheries of Mexico, anecdotal information suggests the presence of escaped
farmed shrimp. According to a researcher at Kino Bay Mexico Center, trawl fishermen note the
regular presence of farm escapees in their catch. Fishermen can distinguish between wild and
farmed white shrimp because farmed shrimp have a softer texture (L. Meltzer, pers. comm., 31
August 2009).
29
Overall, there is little evidence to characterize the frequency of escapes, but the potential exists
because escapes are inevitable in open systems and there are anecdotal reports of escaped farmed
shrimp in the wild. In Mexico, that potential is mitigated somewhat by screened pond exits and
stringent biosecurity protocols to prevent losses. Screens are typically used throughout the
industry in Mexico to retain shrimp (Ocean Gardens Products, Inc., S. Hester, pers. comm., 26
June 2009). In Sonora, disease prevention regulations require that shrimp farms isolate ponds
within farms and carefully monitor entrances and exits (Sanitary Protocol for Sonora Shrimp
Farms aka Protocolo Sanitario, COSAES). These biosafety measures can also reduce the risk of
escapes. Based on the inevitable nature of escapes from open ponds mitigated by retention
efforts in Mexico, this first Primary Factor is ranked a moderate concern.
Primary Factor - Status of escaping farmed shrimp to the surrounding environment
Litopenaeus vannamei (white shrimp) is native to the Pacific coast of Mexico (including the Gulf
of California) where the great majority of Mexican shrimp farming occurs. Smaller-scale shrimp
production on farms along the Gulf of Mexico also use L. vannamei where it is not native but has
been introduced for aquaculture. As the production of non-native L. vannamei on the Gulf of
Mexico is minimal and not thought to be destined for the U.S. market, it is not considered here.
Domestication of captive populations of Mexican white shrimp began the early 1990s. Most
cultured populations originated in the so-called “Melagos” strain, which exhibits increased
growth and disease tolerance when compared to wild counterparts (Juarez 2008). This artificial
selection of L. vannamei over many generations, along with studies (described above) showing
rapid loss of genetic diversity in selectively bred shrimp suggests that farmed shrimp in Mexico
are no longer ecologically similar to their wild counterparts.
Overall, this second Primary Factor is considered a high conservation concern because, although
the species is native, the domesticated stocks are likely to be ecologically and/or genetically
distinct from wild stocks.
Secondary Factors
Litopenaeus vannamei is native to the Pacific coast of Mexico and the Gulf of California. There
is anecdotal information suggesting the presence of escaped farmed shrimp in the wild. As
mentioned previously, trawl fishermen report the regular presence of farmed shrimp in their
catches (Kino Bay Mexico Center, L. Meltzer, pers. comm., 31 August 2009). However, it is
unknown whether escaped farmed shrimp have established self-sustaining populations.
For several factors considered in the Seafood Watch criteria, there is a lack of evidence with
which to judge environmental impacts, and thus these factors are considered unknown. For
example, despite the ecological differences between domesticated and wild L. vannamei, there is
no evidence that genetic introgression has occurred through crossbreeding in the wild.
Worldwide, little research has been done on this issue. In addition, although spawning disruption
of wild fish has been clearly demonstrated for some farmed species, particularly salmon, there
are no studies to date showing spawning disruption due to escaped farmed shrimp. Further,
competition between wild and farmed shrimp is possible based on the proximity of many shrimp
30
farms to important nursery areas for fish and shrimp, but no studies were available to
demonstrate any evidence of competition (or lack thereof).
The stock status of wild shrimp is considered within the Seafood Watch criteria (see Annex 1 for
the detailed ranking of these secondary factors). According to the National Fisheries Institute
(Instituto Nacionál de la Pesca), the Mexican Pacific stocks of white shrimp (L.vannamei) and
blue shrimp (L. stylirostris) are depleted (INP 2009). For white shrimp, there is a continuing
decline in biomass. Stocks of brown shrimp are at their maximum sustainable yield, although
there is a high degree of uncertainty in these stock status evaluations (in the same way as all
these species). Although shrimp populations are inherently resilient, white shrimp stocks are
considered deteriorated and require protective management actions. For detailed information
about Mexican wild shrimp stocks, see the Seafood Watch report
[http://www.montereybayaquarium.org/cr/cr_seafoodwatch/content/media/MBA_SeafoodWatch
_WarmwaterShrimpReport.pdf]. Stocks of white shrimp are therefore considered vulnerable to
increased disturbance and a high conservation concern for this secondary factor.
Synthesis
The great majority of Mexican shrimp farms are open to the environment, and ponds exchange
10% to 30% (or more) each day of their volume. Therefore, despite good management and
biosecurity protocols, the risk of escapes exists and loss of stock is probably inevitable. Although
the majority of escapes may be small trickle losses, the failure of key components such as outlet
screens and filters, as well as catastrophic events such as dyke failures or flooding, could allow
significant numbers of farmed shrimp to escape. There is anecdotal evidence suggesting that
trawl fishermen regularly catch farmed white shrimp, but the general frequency of escapes is
unknown.
After many generations of domestication and selective farming for desirable traits such as
increased growth rates and disease tolerance, shrimp in Mexico are likely to be ecologically
distinct from wild populations. Although there is little evidence for negative interactions or
genetic introgression, the risk exists on theoretical grounds. There is no evidence of spawning
disruption of wild shrimp by farmed shrimp, but competition for resources between wild and
escaping farmed shrimp is possible on theoretical grounds, particularly due to the proximity of
shrimp farms to typical shrimp nursery habitats (esteros). The stock status of wild penaeid
shrimp in the Mexican Pacific and Gulf of Mexico is considered poor, and therefore the
population has increased vulnerability to additional disturbance. Overall, the risk of escaping
farmed shrimp to wild stocks is considered moderate.
Risk of Escaped Fish to Wild Stocks Rank:
Low
Moderate
High
31
Critical
Criterion 3: Risk of Disease and Parasite Transfer to Wild Stocks
Guiding Principle: Sustainable aquaculture operations pose minimal risk for deleterious effects
to wild fish stocks through the amplification, retransmission or introduction of diseases and
parasites.
Primary Factors
• Risk of amplification and retransmission of disease or parasites to wild stocks
• Risk of species introductions or translocations of novel disease/parasites to wild stocks
Secondary Factors
• Bio-safety risks inherent in operations
• Stock status of affected wild shrimp
Various bacterial, viral, fungal and parasitic pathogens have caused major economic losses in all
forms of agriculture and aquaculture. The Mexican shrimp aquaculture industry is no exception.
Similar to many major shrimp-producing nations, dramatic losses caused by bacterial and
particularly viral disease have shaped the development of the industry. While the economic
losses are easily demonstrated, the potential impacts on wild stocks are less obvious.
The abundance of marine species has a high economic and social value, making increases in
disease a concern for society. Pathogen pollution, or the introduction of new disease-causing
agents, is unequivocally increasing disease in the ocean and elsewhere (Lafferty et al. 2004). A
similar form of pathogen pollution occurs in places where domesticated animals are
concentrated. Domesticated animals serve as disease reservoirs and hosts, which can cause rare
species to decline (Lafferty and Gerber 2002). Theoretically this type of disease transmission can
occur in marine systems when mariculture operations maintain a continual source of disease
transmission to closely related native species. During the 1990s, several viruses of marine
penaeid shrimp spread throughout farms worldwide. This viral spread caused devastating losses
to the industry and potentially transmitted these viruses to local marine environments (Briggs et
al. 2005).
Diseases that affect farmed marine shrimp have traveled between farms across the globe. For
example, diseases that were previously only found in Taiwan and China have spread throughout
Asia and into Latin America. The geographic spread of disease in the 1990s and early 2000s has
resulted in billions of dollars in lost revenue annually (Lightner et al., 1997; Clay 2004). White
Spot Syndrome, caused by White Spot Syndrome Virus or WSSV, is perhaps the most
economically damaging disease (Flegal 2006). White Spot Syndrome was first identified in
Japanese shrimp ponds in 1993. Since, it has spread to the major shrimp-farming nations of Asia
and the Indo-Pacific, including Taiwan, India, Thailand, Indonesia, China, Korea, Vietnam,
Malaysia, the Philippines and Bangladesh (Rosenberry, 1999). By the late 1990s, it had spread
across the Pacific to Latin America. In 1999, production in Latin America declined by 44%,
largely due to WSSV (Moss 2002). Disease has also spread from West to East. In 1992, the
Taura Syndrome Virus was first identified in Ecuador. By 1996, the Taura Syndrome caused
mass mortalities throughout the Americas (including the U.S.). It spread to L. vannamei ponds in
Taiwan in 1996 (Moss 2002). The disease is now present in Thailand and mainland China. Once
32
pathogens have spread to new natural waters (or aquaculture facilities), their eradication is
almost impossible (Briggs et al. 2005). Minimal research has been directed at understanding how
these diseases affect wild crustacean populations. The best example of an associated disease
outbreak between farmed and wild shrimp is the collapse of the commercial blue shrimp (P.
stylirostris) industry from infectious hypodermal and haematopoietic necrosis (IHHNV) in the
northern Gulf of Mexico during the late 1980s and early 1990s (Lightner and Redman 1998).
The commercial fishery recovered ten years later. It is unknown whether disease from farms
caused the decline in the wild population.
Because shrimp have a non-specific immune system, viral pathogens affect shrimp differently
than they do fish. Shrimp that appear healthy can carry cryptic viruses and act as carriers (Flegel
2006). For this reason, viruses are particularly troublesome in the shrimp-farming industry. More
than 20 viruses are known to affect farmed and wild penaeid (warmwater) shrimp (Briggs et al.
2005). Eight of these viruses are considered transmissible and of economic importance. These
include WSSV, TSV, yellowhead virus (YHV), spawner-isolated mortality virus disease (SMV)
and IHHNV (Briggs et al. 2005).
Some of these viruses are carried by the major farmed species, L. vannamei, P. monodon and P.
stylirostris, which theoretically can be transmitted to native wild penaeid shrimp populations
(Briggs et al 2005). Blazer and LaPatra (2002) identified three types of interactions between
cultured and wild fish populations that concern pathogen transmission: first, the importation of
exotic organisms for culture can introduce pathogens to an area; second, the movement of
cultured fish, native and non-native, can introduce new pathogens or new strains of pathogens;
and third, intensive fish culture, which can include crowding, poor living conditions and other
stressors, can lead to the amplification of pathogens that already exist in wild populations and
encourage their transmission between wild and cultured populations.
The possible mechanisms for the transfer of pathogens include the direct interaction between
infected and non-infected shrimp via escapement, the movement of predators between ponds
(e.g.,birds and crabs), the passive movement of water between pond walls and release of infected
water. Research concerning viral transmission between shrimp is in its infancy, even for the most
threatening shrimp diseases, such as WSSF, TSV and YHV. For example, it is not clear whether
shrimp viruses can survive in water or outside of a host. Recent research has shown that
zooplankton may be a vector for the transmission of WSSV (Mang et al. 2007; Zhang et al.
2008). If this is the case, then this mechanism may work in conjunction with bird predation, crab
movement or the passive movement of water to cause disease outbreaks within and between
farms. This finding would also indicate that the flow of farm water to the environment creates a
high risk for the retransmission of pathogens from the farm to wild animals.
Disease can affect production systems of varying intensity, in different climates and between
different species. Typically, more intensive farms present an environment that is more conducive
to disease because shrimp are crowded and under more stress. Generally, extensive farms are less
likely to create stressful conditions that lead to increased disease.
Juarez (2008) gave the following summary of Mexico’s disease history:
White Spot Syndrome Virus (WSSV) is without question the shrimp disease of highest
33
economic significance in Mexico. It appeared on the Pacific coast in 1999 and by 2000
It caused serious loses to shrimp farms in Sinaloa. White Spot disease accounts for most of
the farming risk in the Pacific coast of Mexico. Interestingly, so far it has not caused major
mortality in Sonora north of Guaymas. Temperatures characteristic of this desert area and the
obligated periodic drying that the farms get every year after the season, with no mangrove
areas, provide few natural reservoirs for the virus. WSSV has not been reported from
Mexican farms on the Gulf of Mexico coast, nor has it been found at farms in Baja California
Sur. Taura Syndrome Virus (TSV) first appeared in Mexico in 1995 and resulted in serious
epizootics in Sinaloa. Virulence peaked in 1996 and was followed by a steady decline. By
1998, shrimp production in Sinaloa had stabilized. Today TSV is considered a manageable
problem that can be mitigated with general stress avoidance and good husbandry practices.
Necrotizing Hepatopancreatitis (NHP) was reported in Mexico in 1999. If left unchecked it
can cause serious losses, especially during the warmest months, but farmers have learned to
spot the early signs of disease, and to prevent serious losses by use of medicated feed.
Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) had not been reported in
Mexico before 1987, but it is now present in all wild and captive populations. The virus is
well tolerated under culture conditions, and results in only minor size disparity and
deformities. During 2005 and 2006 a disease characterized by muscle necrosis and chronic
mortality affected shrimp farms in the Gulf of Mexico states of Yucatan and Campeche. The
disease was serious enough to cause the closing of shrimp farms in the area. Similar signs
were observed at farms in neighboring Belize. Although signs of this disease were somewhat
similar to those caused by Infectious Mionecrosis Virus (IMNV), samples did not react with
the IMNV gene probe. Recently, Pantoja et al. reported a new virus from Belize samples,
named Litopenaeus vannamei Nodavirus (LvNV) that causes comparable clinical signs. It is
possible, although not proven, that LvNV is also responsible for the problems observed in
Yucatan and Campeche.
In contrast to the Mexican Pacific coast shrimp-farming industry, COSAES reports that tests
have not detected the presence of YHV or IMNV in either cultured and wild shrimp populations
for the state of Sonora on the Gulf of Mexico coast. Additionally, the presence of TSV in farmed
shrimp is reported as “very low” (pers. comm., 12 October 2009).
There have been recent advances in shrimp disease management in Mexico. Recently, fallowing
of farms has become widespread throughout the Mexico shrimp industry. Cold winter
temperatures north of the Midriff Islands have always forced farmers to fallow farms for
approximately six months. Additionally, many of the farms in the central and southern Gulf of
California have begun using ponds for only 6 to 9 months out of the year, according to Dr.
Richard Brusca, Senior Director of Conservation and Science at the Arizona-Sonora Desert
Museum and a Research Scientist at the University of Arizona (pers. comm., 26 June 2009). The
fallow time for each pond allows the sediment to “cleanse” itself of pathogenic microbes (e.g.,
Vibrio).
As a result of serious disease problems in its shrimp-farming industry, Mexico has taken a proactive role in disease management among its shrimp farmers. Mexico is unusual among shrimpfarming nations due to its establishment of Comités Estatales de Sanidad Acuícola, (loosely
34
translated as State Committees on Aquaculture Health), which have publicly available data on
shrimp production, disease and health monitoring. The State Committees work jointly with the
state government through the department of Agriculture (SAGARPA), the National Service of
Alimentary Health, Quality and Innocuity (SENASICA) and the National Commission of
Aquaculture and Fisheries (CONAPESCA). In the state of Sonora, (the Mexican state with the
highest production), the committee is the Comité de Sanidad Acuícola del Estado de Sonora, AC
(COSAES). Its objective is to promote disease prevention through good practices and sanitary
handling in aquaculture, and to diminish and avoid conditions that favor the presence of
pathogenic agents and their dissemination. The Committees state that this objective can be
achieved through a variety of ways. For example, COSAES states (pers. comm., 12 October
2009, translated from Spanish):
The state of Sonora was the first to issue an aquaculture state law in Mexico in December
2005. Those laws implemented health measures to prevent disease and control its spread
(described in articles 128 and 129 of the Law on Fisheries and Aquaculture for the State
of Sonora). These health measures are aimed at preventing, controlling, combating and
eradicating diseases and pests that may affect or concern fisheries and aquaculture, which
include: 1) quarantine; 2) sanitation; 3) securing and, where appropriate, disposing of
fishery and living aquatic resources, products, its byproducts, chemicals,
pharmaceuticals, biological, and food products, or 4) the temporary suspension of part or
all of the operation of the facilities of farms or aquaculture management units or
diagnostic laboratories or manufacturers of aquatic resources for fisheries or aquaculture.
Many details are outside the scope of this report but can be found in Spanish at
www.cosaes.com. In the case of a disease outbreak, the infected shrimp, pond structure and
water must be disposed of or treated in order to contain the outbreak. Once a virus has been
detected, farms are prohibited from discharging water into the environment. Failure to comply
entails heavy financial penalties. These strict biosecurity measures are noteworthy and,
according to COSAES, have resulted in increased animal health and production yields (pers.
comm. 12 October 2009). Under normal operating conditions, pond water cannot be discharged
into areas that source their own supply or that of other farms. However, farms may not adhere to
this last biosafety requirement regarding discharge. For a detailed description of farm outputs,
refer to Criterion 4: Risk of Pollution and Habitat Effects, .
Mexico achieved a clean record on Specific Pathogen Free (SPF) broodstock and postlarvae in
hatchery samples taken in 2008. To date, similar results have been collected for 2009.
Broodstock and postlarvae are routinely tested for:
•
•
•
•
•
•
White Spot Syndrome Virus (WSSV),
Yellowhead Virus (YHV),
Taura Syndrome Virus (TSV),
Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV),
Necrotising Hepatopancreatitis (NHP), and
Infectious Myonecrosis Virus (IMNV).
35
Despite this clean record at stocking, clinical disease outbreaks continue to occur in Mexican
shrimp farms. Figure 11 shows the occurrence of outbreaks in Sonora between 2004 and 2008. In
2008, there were 169 registered farms in Sonora.
No. of Farms Figure 11. Number of farms in Sonora affected by four major shrimp diseases between 2004 and 2008. Graph
from www.cosaes.com.
Figure 11 shows no uniform trends in disease occurrence over the period 2004 to 2008. WSSV,
NHP and IHHNV all showed increases from 2007 to 2008. There were a considerably higher
number of WSSV cases in 2008, compared to an unusually low level of disease in 2007.
Table 7 shows 2008 disease data at the farm level in Sonora as well as the number of farms
applying antibiotics in 2008. Antibiotics would not be used to treat the viral diseases under
discussion but may be used to treat secondary bacterial infections. Antibiotic use can also give an
indication of bacterial disease outbreaks.
Although TSV was absent in 2008 (Table 7), almost a quarter of farms reported WSSV and over
a third experienced NHP. In terms of mortality rates, the severity of these outbreaks remains
unknown . It is not possible to make clear conclusions about disease or antibiotic use across the
state of Sonora because antibiotics were not used due to the relatively few number of farms in
the central region. According to COSAES, the 2009-2010 health care management plan for
shrimp farming in the state of Sonora is designed to eradicate WSSV from farms. The goal is to
declare shrimp farms as virus-free or low prevalence zones for WSSV and YHV (pers. comm.,
12 October 2009).
36
Sonora
Region
Caborca
Bahia Kino
Cardonl
Tastiota
Guaymas
Cruz de Piedra
Lobos
Melagos
Atanasia
Tobari
Siari
Aquiropo
Ritto
Sta Barbara
Agiabampo
Totals
Percent of farms
Farm
s
North
Central
South
0
14
7
12
1
6
8
23
23
14
5
6
10
3
2
134
100.0
WSSV
NHP
4
7
6
5
4
TSV
2
3
9
7
1
3
5
9
1
2
1
1
2
46
34.3
5
1
1
33
24.6
IHHNV
Farms
applying
antibiotic
4
5
2
6
1
8
0
0
0
2
4
0
1
2
2
0
0
26
19.4
2
1
1
2
1
0
0.0
18
13.4
Table 7. Number of farms by Sonoran region with disease and antibiotic use during 2008 (data collected until
December 15, 2008 and compiled from COSAES 2009).
Figure 12 shows that the number of farms using antibiotics decreased considerably between 2007
and 2008 in all regions of Sonora., but the number of farms using antibiotics remains significant.
In 2008, over 44% of farms in the north and 19% of farms in all of Sonora used antibiotics. Data
is not available on the quantities or the number of treatments made by each farm.
North Central South Figure 12. The use of antibiotics in 2007 and 2008 in Sonora.
Despite the inherent difficulties in dealing with shrimp diseases, the Mexican shrimp-farming
industry has progressive regulations and practices in place that are intended prevent and control
37
outbreaks on farms in order to minimize production losses due to disease. However, this
Criterion focuses on the risk of disease retransmission from farms to wild stocks.
Primary Factors - Risk of amplification and retransmission of disease or parasites to wild
stocks AND Risk of species introductions or translocations of novel disease/parasites to
wild stocks.
Currently, disease transmission from wild to farmed shrimp is better documented than disease
transmission from farmed to wild shrimp. For example, Lightner and Redman (1998) found that
WSSV spread from wild organisms to farmed shrimp in Asia. In 2000, Nunan et al. (2001) found
WSSV in 2% of wild L. vannamei in Panama. Although WSSV has been widely eradicated from
U.S.-farmed shrimp, it is probably established in U.S. stocks of wild shrimp, crabs and crayfish.
However, its effects have not been quantified. Various other crustacean species are also
susceptible to WSSV. According to Lightner and Redman (1998), wild postlarvae infected with
TSV were found near infected shrimp farms in Ecuador, off the coasts of Honduras, El Salvador
and southern Mexico. TSV infections were also found in wild escapees of L. vannamei in the
U.S. as well as in wild populations of P. monodon in Taiwan. Nunan et al. (2001) found TSV
prevalence in wild populations off Panama to be 28%. Kiatpathomchai et al. (2008) documented
that five wild crustacean species in Thailand, once experimentally exposed to TSV, did not die
but did react to the virus. Their results indicate that these species may act as disease carriers,
which can infect the SPF L. vannamei that are stocked in shrimp ponds.
The issue of disease retransmission to wild from farmed shrimp was discussed in the RAMSAR
site report for Laguna Playa Colorada-Santa María La Reforma in Sinaloa (see Criterion 4B).
The report states that shrimp farms have brought many environmental impacts, including ‘the
spread of viruses from farmed to wild populations. However, the report does not provide further
evidence. A study conducted in 1997 and 1998 detected WSSV, but not TSV or other pathogens,
in wild white and brown shrimp (Litopenaeus Setiferus and Farfantepenaeus aztecus,
respectively) off the coast of Texas (Dorf et al. 2005). The presence of WSSV in wild stocks
may have come from farm effluent or escapees. It could also have come from the multitude of
non-farm related vectors listed above (e.g., predatory birds and crabs, zooplankton). Surveys
conducted 1997-2000 checked for the presence of farm viruses in wild stocks, but produced no
evidence of diseased animals in the wild (Dorf et al. 2005). In 2004, WSSV was reported for a
second time in native L. setiferus stocks off the coast of Mississippi in the Gulf of Mexico waters
(Treece 2008). However, a similar study surveying wild shrimp along the Gulf of Mexico in
areas adjacent to Mexican shrimp farms did not provide evidence of diseased animals (ChavezSanchez et al. 2007).
As previously mentioned, Lightner and Redman (1998) provide strong evidence in support of an
association between a virus in a wild population with the same virus (IHHNV) at a local shrimp
farm. Their report documents that commercial blue shrimp (P. stylirostris) landings in the Gulf
of Mexico fell by approximately 1000 tons per year for four years, beginning in the 1987-88
season. The outbreak may have originated with the release of cultured shrimp that were infected.
However, the cause of the outbreak is not certain.
Despite the lack of clear empirical evidence regarding retransmission of pathogens to wild stocks
38
from farmed shrimp, theoretical risk exists because farms tend to amplify pathogens. It is
generally understood that disease amplification occurs on shrimp farms. Farmed animals and
wild populations do not typically experience the same environment. Wild shrimp populations are
prolific and short-lived, making them somewhat resistant to catastrophic events. On the other
hand, the farm environment increases shrimp density and proximity, providing some protection
from predators that would otherwise cull diseased animals. The farm environment serves to
amplify viruses and increases the likelihood of disease outbreaks.
In Mexico, hatchery testing of broodstock and postlarvae in Mexico indicates that newly stocked
shrimp are free of specific pathogens. Common shrimp diseases exist in the farm environment,
enter the farm in water during daily exchanges or SPF shrimp can act as asymptomatic carriers,
but the farm conditions amplify the disease. The presence of disease on farms presented above
(using the State of Sonora as an example) combined with the disease-free nature of postlarvae at
the time of stocking into ponds demonstrates that disease amplification occurs in Mexican
shrimp farms.
Regardless of their origin, the consequences of pathogen outbreaks must be considered when
assessing risk. Disease outbreaks have devastated both farmed and wild shrimp stocks. Although
the cause of disease is unknown, declines in the Gulf of Mexico shrimp fishery for
approximately 10 years, beginning in the 1987-88 season, illustrates the severe consequence to
wild stocks.
There is a general lack of evidence regarding the retransmission of pathogens (whether native or
novel) to wild stocks from farmed shrimp. However, retransmission is likely and the
consequences can be severe. Due to the amplification of diseases on farms, there is a theoretical
risk of retransmission from farmed to wild stocks in Mexico. This risk is considered a moderate
conservation concern for the first primary factor.
The second primary factor considers novel pathogens. It is difficult to determine whether
aquaculture is responsible for introducing or transferring novel diseases to wild populations
without knowledge of which diseases existed pre-aquaculture. Shrimp diseases have spread and
been established worldwide, blurring the distinction between “endemic” and “novel”. Therefore,
the second portion of this primary factor is considered “unknown”.
Secondary Factor - Bio-safety risks inherent in operations
Biosecurity has been defined as "...sets of practices that will reduce the probability of a pathogen
introduction and its subsequent spread from one place to another..." (Lotz 1997).
According to the FAO (2003):
The basic elements of a biosecurity program include the physical, chemical and
biological methods necessary to protect the hatchery from the consequences of all
diseases that represent a high risk. Effective biosecurity requires attention to a range of
factors, some disease specific, some not, ranging from purely technical factors to aspects
of management and economics. Various levels and strategies for biosecurity may be
employed depending on the hatchery facility, the diseases of concern and the level of
39
perceived risk. The appropriate level of biosecurity to be applied will generally be a
function of ease of implementation and cost, relative to the impact of the disease on the
production operations. Responsible hatchery [farm] operation must also consider the
potential risk of disease introduction into the natural environment, and its effects on
neighboring aquaculture operations and the natural fauna.
Like the issue of escapes, the risk of disease retransmission to wild stocks appears to be
dependent on the type of aquaculture system used. Open systems carry the highest probability of
disease retransmission. Any system with water entering the environment carries some risk.
Closed and semi-closed aquaculture systems have the lowest potential for releasing pathogens
into the environment (Blazer and LaPatra 2002). Wastewater from these closed and semi-closed
systems can be treated, and intermediate hosts and carriers (for example birds, snails, and crabs)
can be excluded from the culture facility. On the other hand, pond and flow-through systems
pose some risk of pathogen transfer to wild populations of shrimp. Both systems can spread
diseases through the discharge of wastewater and escapes of farmed shrimp. Additionally, these
systems are frequently open to intermediate hosts (such as birds). Intermediate hosts may
potentially transport pathogens from one farm to another and between farms and the wild.
Disease can be spread in farming operations by many potential vectors. The great majority of
shrimp farms in Mexico are located on coastal land. which provides a direct connection to the
open environment through daily water exchanges of 10-30% (or more). Daily water exchanges
provide a transmission route for diseases from the farm to the wild. In addition, shrimp farms
frequently discharge their wastewater (potentially containing pathogens) into estuaries
(particularly the distinct ‘esteros’ in Mexico) and coastal waters that are used as nursery areas by
wild shrimp postlarvae and juveniles. This method of wastewater disposal provides a plausible
route of disease retransmission.
In 2005, the Mexican state of Sonora established a sanitary protocol (Protocol Sanitario Para Las
Juntas Locales de Sanidad Acuicola 2005) for its shrimp farms. It is unclear if this protocol is
followed in other shrimp-producing states in Mexico. The objective of the protocol (loosely
translated) is to: facilitate the application of good culture practices that allow the prevention and
early detection of diseases, and avoid their dispersion. It covers the following aspects:
•
•
•
•
•
•
•
•
•
•
•
•
Preparation of ponds and reservoirs,
Maintenance of drains and canals,
Filling the reservoir and ponds,
Fertilization,
Selection and transport of postlarvae,
Stocking,
Development of the culture,
Observations of shrimp health,
Biosecurity measures,
Sanitary measures during culture,
Measures for harvest before outbreaks of high-impact diseases, and
Recording of statistical production data.
40
In addition, the protocol states: “In order to minimize the risks in the transmittal of high impact
illnesses, all farms are prohibited from discharging water in bodies of water that are the source of
their own supply or that of other farms.” In Sonora, the protocol is mandatory, regulated by the
state Acuicola law, and coordinated by federal law (Ocean Garden Products, Rodrigo De La
Serna, Vice President of Operations, pers. comm., 27 May 2009). However, Lorayne Meltzer
suggested that in the region covering Bahia Kino to Estero Tastiota, this protocol may not be
adequate to protect the environment or the farms. In that 100-km region, shrimp farms span the
coast almost without interruption, farms exchange as much as 30% of their water daily, and
effluents discharged into esteros or the open coast are located near the intake areas (Kino Bay
Mexico Center, L. Meltzer, pers. comm., September 2009). Under these circumstances,
wastewaters may be the source for shrimp farms in this region. Without regular water quality
monitoring, it is not possible to determine whether farmers are drawing wastes back into their
farms.
In addition, following the advice of the sanitary protocol may prevent re-infection of the same or
neighboring farms. However, the 10-30% daily water exchange must be discharged somewhere
(for a detailed description of farm outputs, refer to Criterion 4: Risk of Pollution and Habitat
Effects). The health and antibiotic records described above indicate that diseases are still present
in many Mexican shrimp farms. Uncertainty remains as to whether the sanitary protocols contain
adequate measures to prevent the loss of pathogens to the external environment during daily
water exchanges or from the escape of infected animals.
Overall, the openness of shrimp farms in Mexico creates a high risk of pathogen loss to the
environment.
Secondary Factor - Stock status of affected wild shrimp
According to the National Fisheries Institute (Instituto Nacionál de la Pesca), the Mexican
Pacific stocks of white shrimp (L.vannamei) and blue shrimp (L. stylirostris) are depleted (INP
2009). For white shrimp, biomass continues to decline. Stocks of brown shrimp are at their
maximum sustainable yield, although there is (in the same way as all these species) a high degree
of uncertainty in these stock status evaluations. Although shrimp populations are inherently
resilient, white shrimp stocks have deteriorated and require protective management actions. For
detailed information about Mexican, wild shrimp stocks, see the Seafood Watch report
[http://www.montereybayaquarium.org/cr/cr_seafoodwatch/content/media/MBA_SeafoodWatch
_WarmwaterShrimpReport.pdf]. According to Seafood Watch Criteria, wild shrimp stocks in
Mexico have a high conservation concern.
Synthesis
Diseases affecting farmed shrimp have been transported between farms across the globe.
Evidence of the direct impacts on wild shrimp populations from the amplification, retransmission
or introduction of novel pathogens is inherently difficult to detect, but there have been
widespread catastrophic disease outbreaks at shrimp farms. Due to the severe disease problems
suffered by the developing shrimp-farming industry in Mexico, steps have been taken to reduce
the likelihood of outbreaks and economic losses for farms. While reductions in disease are
beneficial for all concerned parties, the degree to which these precautionary measures will
protect wild shrimp populations from shrimp-farm pathogens is unclear.
41
The frequent outbreaks of highly virulent shrimp diseases that occur in Mexican shrimp ponds
during the grow-out cycle demonstrates that disease amplification is occurring because Specific
Pathogen Free broodstock are introduced and the ponds are stocked with disease-free postlarvae.
The direct connection with the external environment via 10-30% (or more) daily exchanges of
the ponds water also suggests the potential for transmission of pathogens from the farm into
environments inhabited by wild shrimp (for example, wild shrimp nursery areas).
In this Seafood Watch analysis, the evidence of disease amplification within farms, the open
nature of the production system and the vulnerable state of wild stocks results in a ‘high’ ranking
for this criterion (See Annex 1 for more details).
Risk of Disease Transfer to Wild Stocks Rank:
Low
Moderate
High
Critical
Criterion 4: Risk of Pollution and Habitat Effects
Guiding Principle: Sustainable aquaculture operations employ methods to treat and reduce the
discharge of organic effluent and other potential contaminants to ensure that the resulting
discharge and other habitat impacts do not adversely affect the integrity and function of the
surrounding ecosystem.
Factors:
A – Effluent Effects
• Effluent water treatment
• Evidence of substantial local effluent effects
• Evidence of regional effluent effects
• Extent of local or regional effluent effects
B – Habitat Effects
• Potential to impact habitats – location
• Potential to impact habitats – extent of operations
This section focuses on the Pacific coast of Mexico and, in particular, the Gulf of California
where more than 90% of Mexico’s farmed shrimp production takes place. As previously
mentioned, shrimp production in the Northwestern states of Mexico is dominant and has great
importance for U.S. imports.
The Gulf of California has one of the most diverse marine biological communities in the world
(Lluch-Cota et al. 2007). It is the only inland sea in the Eastern Pacific, the most important
fishing region in Mexico and one of the most closely watched marine systems by the worldwide
conservation sector. Also known as the Sea of Cortez (Mar de Cortes), the Gulf of California is a
42
body of water that separates the Baja California Peninsula from the Mexican mainland (22–32°
N and 105–107° W). The Gulf is 1130 km long and 80–209 km wide. In the northern region, the
mean offshore depth is about 200 m. In this region large amounts of sediments are maintained in
suspension by strong currents that result from the extreme tidal range that reaches up to 6.95 m.
There is an archipelago containing sills, channels, basins and two large islands, Islas Angel de la
Guarda and Tiburón, south of the shallow, sediment-filled northern basin. South of these large
islands, the Gulf of California increases in depth towards the mouth, with deep basins reaching
over 3000 m. The peninsular shore has desert climate conditions with almost no drainage from
rivers; it is mostly rocky with some scattered sandy stretches and a narrow shelf. In contrast, the
continental shore is characterized by long sandy beaches, large costal lagoons and open muddy
bays. The continental shore also has a wide shelf and is where the majority of shrimp farms are
located. In the southern region (i.e., Nayarit), large supplies of freshwater reach the coastline
directly or through the lagoons.
A - Effluent Effects
The water quality of effluent discharged from shrimp farms is dynamic and depends on several
aspects of the farm production system as well as on its management. The quantity of the effluent
load discharged depends upon the pond water quality and the water exchange rate. The potential
for the greatest impacts results from high daily exchange rates of poor quality pond water. There
is less potential impact from closed or semi-closed systems (such as earthen shrimp ponds)
wherein natural processes help mitigate pollution. Water reuse systems also have less potential
impact because there is treatment and disposal of wastes, and discharges are infrequent (Boyd et
al. 2008). In Mexico, shrimp pond effluents are discharged without treatment.
According to Boyd et al. (2008), earthen ponds have a remarkable ability to assimilate nitrogen
and phosphorus through physical, chemical and biological processes. However, ponds often have
higher concentrations of nutrients, plankton, suspended solids and oxygen demand than the water
bodies into which they discharge. Discharging nutrients and suspended solids into receiving
waters can have adverse effects, including stimulating algal blooms and creating hypoxic or
anoxic conditions (Burford et al. 2003). According to Vaiphasa et al. (2007 and references
therein), the waste materials that are discharged from shrimp farms comprise liquid biochemical
substances as well as non-soluble and soluble solid biochemical substances. These substances
include fertilizers, pesticides and disinfectants, antibiotics, immunostimulants, vitamins and feed
additives.
As pointed out by Boyd (2003), fish and shrimp farms tend to be concentrated in specific
regions, but typically they are sprawling operations where large volumes of relatively dilute
effluents are released at many points. In these cases, effluents from pond aquaculture resemble
non-point sources of pollution more than point sources. In Mexico, the conditions are different.
According to the Arizona-Sonora Desert Museum department of Conservation and Science,
shrimp ponds in the Gulf of Mexico usually have only one, or at most two or three coastal
effluent discharge points (R. Brusca, pers. comm., 26 June 2009). Within the 100-km stretch
from Estero La Cruz near Bahia Kino to Estero Tastiota (Sonora), there are only 4 to 6 outflows
from shrimp farms (COSAES 2009). In this region, the effluent represents point sources of
pollution that can be monitored and regulated.
43
Regardless of the nature of the source, according to Gonzáles-Ocampo et al. (2006), the most
important negative effect of supra-littoral and semi-intensive shrimp farms on the semi-arid coast
of Mexico is caused by pollutant-enriched water discharges. The nutrient dynamics and nutrient
budgets of typical shrimp ponds are depicted in Figures 13 and 14.
Figure 13. The source of pollutants in shrimp operations. Graphic from Sonnenholzer (2008).
Figure 14. Nitrogen budget and fate of pollutants in intensive shrimp ponds. Adapted from Funge-Smith and
Briggs (2003) in Sonnenholzer (2008).
44
Although Figure 14 was originally published in a 1998 paper, it is still considered a correct
approximation of shrimp pond nutrient dynamics. This model shows that 30% of the nitrogen
inputs and by-products are broken down within the ponds, 18% of the inputs leave the pond as
harvested shrimp, 27% leave the farm during daily water exchange and harvest, and up to 24%
may be discharged via pond sediment. Thus, almost half of the nutrient inputs are assimilated by
either pond processes or are absorbed by the shrimp.
The exact fate of nutrients released to receiving waters from shrimp farms is often unclear, but
there have been some case studies of nutrient impacts from shrimp farms in various regions of
the world. The work by Boyd and Gautier (2000) emphasizes the high degree of variability in
nutrient outputs. They found a large range of concentrations of various water quality parameters
in shrimp farm effluents. Nitrogen varied from 0.02 to 2,600 mg/L (median 2.4), phosphorous
varied from 0.01 to 110 mg/L (median 2.6) and total suspended solids varied from 10 to 3671
mg/L (median 10 mg/L). Trott et al. (2004) confirmed the natural ability of ponds to process
nutrients. They found that high sedimentation rates combined with rapid accumulation prevented
the release of most carbon and nitrogen from Muddy Creek in Australia. Trott et al. concluded
that the lack of obvious eutrophication was due to a combination of biological and physical
processes operating within the creek, such as:
• Rapid settling of nutrient rich particulates within the forest and creeks,
• Effective flushing and scouring of sediments during spring tides and/or wet season runoff,
• Rapid grazing by zooplankton,
• Rapid consumption of particulates and zooplankton by mobile fish populations, and
• Intermittent seasonal farm discharges that allow ‘‘fallowing’’ of the estuary.
Within the Gulf of California, the degree of pollution and habitat modification may be roughly
divided into three zones (Lluch-Cota et al. 2007): the western coast, the eastern coast and the
northern area. The western coast of the Gulf has tourist appeal, and some infrastructure has been
built. Population density is relatively low (except for areas at La Paz Bay and Los Cabos, and the
coast is nearly pristine (Ortiz-Lozano et al. 2005). On the other hand, much of the eastern coast
experiences pollution from industrial and human wastes, aquaculture effluent and agricultural
run-offs. The majority of shrimp farms are on the eastern coast. According to Kino Bay Mexico
Center, shrimp farms have altered the habitat almost without interruption for 100 km between
Estero La Cruz (near Bahia Kino) and Estero Tastiota in Sonora (L. Meltzer, pers. comm., 4
September 2009).
A recent study by Miranda et al (2007) describes the nutrient outputs from shrimp farms on the
eastern Gulf coast in Mexico. Miranda et al. (2007) describe a semi-intensive shrimp farm in
Sonora with a 12.7% daily water exchange rate and a final yield of 2,000 kg/ha. During the
single six-month production cycle, the farm discharged 547 kg of nitrogen, 73kg of phosphorous
and 20.8 tons of total solids per ha of pond area. The water body that received these discharges
was the Moroncarit Lagoon, which has an estimated mean water residence time of 3 to 5 d and
receives agricultural drains and sediments of marine origin. Miranda et al. (2007) did not
measure effluent impacts, but said that the substantial amounts of nutrients and sediments
discharged by the shrimp farm were bound to impact the trophic status of the semi-enclosed
45
Moroncarit Lagoon. In order to improve both ecological and economic performance, the authors
concluded that nutrient abatement should be a priority for modern shrimp farming.
COSEAS provided a report that compared the water quality between discharges from shrimp
farms into Bahio Kino to the quality of water near an offshore island used as a control (pers.
comm., 13 November 2009). The report found that drainage from shrimp farms in Bahio Kino
had significantly higher salinity, total suspended solids, organic particles, chlorophyll a, Vibrio
bacteria, low dissolved oxygen values and low transparency compared to the control area. In
contrast, the report stated that shrimp-farm discharges did not contain high levels of inorganic
nutrients (e.g., NO2, NO3, PO4-P) compared to the control area. The report also found that Bahio
Kino assimilated the excess salts and oxygen demand, but that water transparency in the bay and
the estuary were affected. Thus, the discharges from shrimp farms significantly contributed to
declines in water quality, particularly due to increased primary productivity from nutrient
enrichment.
Another case study (unpublished) comes from a 100-km stretch of coastline south of Bahia Kino
to Estero Tastiota in Sonora on the eastern Gulf coast where there are few enrichment sources
other than shrimp farms (Kino Bay Mexico Center, L. Meltzer, pers. comm., 14 September
2009). According to COSAES (2009), there were approximately 37 farms in this region covering
more than 10,600 ha in 2008, and in the next five years 15,000 more ha of shrimp farms will be
added. Ms. Meltzer’s group calculated water inputs and outflows for the shrimp farms in this
area. They estimated that approximately 30 million m3 of untreated effluent flows into estuaries
and coastal areas each day, which is equivalent to 10,000 Olympic-sized pools per day (Kino
Bay Mexico Center, L. Meltzer, unpublished data, pers. comm., 8 September 2009). The intake
and outflow canals in this region leave visible sediment plumes. Some farms regularly use
antibiotics and fertilizers. There are 12 farms discharging effluent directly into Estero Tastiota,
resulting in increased sedimentation and nutrient loading. These conditions have led to
subsequent changes to the small-scale fisheries and almost complete loss of the oysterculture
operations. Although water quality assessments are mandated, testing is inconsistent. Despite the
fact that some farms use good management practices based on self-regulation, there are
unregulated cumulative effects due to the large number of farms and the large volume of effluent
(Kino Bay Mexico Center, L. Meltzer, pers. comm., 5 August 2009).
Other than what can be inferred from these case studies, there is a general lack of direct evidence
documenting local impacts exclusively from shrimp-farm effluents due to the presence of other
significant sources of nutrient enrichment (refer to the unpublished case study, described above).
An important control-impact study would include regular year-round water quality monitoring at
outflows. Ideally, this study would include a control, i.e., testing in areas of the coast without
outflows (L. Meltzer, pers. comm., 3 September 2009). The published research currently
available includes various studies authored by Paez-Osuna and colleagues (e.g., Páez-Osuna et
al. 1999; Páez-Osuna et al. 2003; Páez-Osuna and Ruiz-Fernández 2005), who investigated and
modeled nutrient outputs from shrimp farms, agricultural and anthropological sources into the
Gulf of California. They report that nutrient outputs from shrimp-farm effluent are substantial,
but that agricultural sources of effluent are greater. According to Páez-Osuna et al. (2003):
46
“Water effluents from shrimp farms, in addition to municipal, agricultural and industrial
wastewater, are discharged directly to coastal waters from the Gulf of California; such
discharges are not subjected to previous treatment. Knowledge of how shrimp pond
effluent affects coastal waters and how it affects aquaculture activities is just beginning.”
Factors that may mitigate effluent pollution include incomplete drainage at harvest, fallowing of
ponds between shrimp cycles, use of excess sludge as fertilizer and locating farms inland. Onecycle farms (the dominant production method for shrimp exported from Mexico) are allowed to
lie fallow from December through March. Two-cycle farms lie fallow approximately December
through February. According to Ocean Gardens Products, Inc., if the pond sludge is more than
several centimeters, it is collected and used for fertilizer (S. Hester, pers. comm., 24 June 2009).
Otherwise, the dried sludge is worked into the soil during preparation for the next cycle of
shrimp production. However, these mitigation efforts do not address the untreated nutrients that
leave the farm during daily water exchange.
In addition to local effects, nutrient enrichment can alter ecosystems on a regional scale. It has
been demonstrated that agricultural runoffs are also related to phytoplankton blooms in some
areas of the Gulf of California, specifically offshore of the Yaqui Valley discharge (Beman et al.
2005) located in southern Sonora. Ahrens et al. (2008) studied nutrient inputs and outputs from
the Yaqui Valley on the Gulf of California coast of Mexico. Figure 15 shows a graphical
representation of their results. Although the data presented in the paper were not precise, they
indicate that nitrogen effluents from Mexican shrimp farms may play a relatively minor role in
the southern Gulf of Mexico when they are compared to other sources entering the coastal waters
in this region, particularly agricultural run-off. Nonetheless, the contribution from shrimp
farming to nutrient enrichment into the Gulf of California is indeed substantial. The model by
Páez-Osuna and Ruiz-Fernández (2005) estimates that the combined N and P output from shrimp
farms in Mexico annually is equivalent to the amount found in untreated sewage from 1.7 and
1.9 million people, respectively.
47
Figure 15. Nutrient inputs and outputs for the Yaqui Valley, Mexico. From Ahrens et al. (2008).
Similar to local impacts, it is not always clear how much of these harmful regional impacts are
due to outputs from shrimp farms because there are other substantial sources in the Gulf of
California. Along with the great majority of shrimp farms, intensive agriculture systems are
mainly found in Sonora and Sinaloa, providing 40% of the national agriculture production
(Enriquez-Andrade et al. 2005). In another study, Miranda et al. (in press) estimated the nutrient
inputs into the Gulf of California off the states of Sonora and Sinaloa in 2003. Inputs were
calculated from agriculture run off, rivers, municipal sources and shrimp farms. The authors
found that agricultural sources accounted for more than half of the N and P inputs, and
aquaculture effluents accounted for approximately 10% and 3%, respectively. Particularly in the
Yaqui Valley (southern Sonora), fertilizer application rates are extremely high (250 kg N/ha),
and these materials are quickly washed out by surface water run-off from irrigation (Lluch-Cota
et al. 2007). Beman et al. (2005) related the irrigation activity and run-off intensity from the
Yaqui Valley to meso-scale phytoplankton blooms, as revealed by satellite imagery. They
suggested that up to 22% of the annual chlorophyll variability in the Gulf of California is related
to the nitrogen run-off from the Yaqui Valley. According to Arizona-Sonora Desert Museum
Department of Conservation and Science, the majority of Sonoran agriculture no longer drains
into the Sea of Cortez. This change may lighten the agricultural contribution to coastal pollution
in Sonora. Additionally, any contribution from north of the Rio Yaqui is now quite minimal (R.
Brusca, pers. comm., 26 June 2009). Lluch-Cota et al. (2007) described the figures (from Beman
et al. 2005) as controversial. Although the contribution from aquaculture appears to be relatively
low compared to agricultural sources, the combined impact of agriculture and aquaculture is
significant and harmful.
48
Harmful algal blooms (HAB) can substantially impact marine ecosystems (Lluch-Cota et al.
2007). Since 1943, massive marine life mortality events have been associated with HABs in the
Gulf of California (Osorio-Tafall 1943). Increased mortality of various animal groups, such as
sea birds, turtles, fish and marine mammals, follow these marine life die-offs. Lluch-Cota et al.
(2007) reported massive mortalities of marine mammals in the Gulf of California during 1995
1997 and 1999, most likely caused by (HABs). The only long and consistent HAB time series in
the Gulf (22 years at Mazatlan Bay) shows that the number of toxic species as well as the
frequency and duration of events are increasing (Cortés-Altamirano et al. 1999). Estuaries
(esteros) in the Gulf of California with shrimp farms, such as those at Guaymas and Bahia Kino,
have reportedly experienced increased incidences of red tide blooms and fish die-offs (Glenn et
al. 2006). Although the relative contributions of effluent from shrimp farms and agriculture to
these negative impacts is unknown, it is clear that aquaculture has the potential to contribute to
negative impacts such as HABs.
Another important potential impact is the effect of effluent release on the health of mangrove
ecosystems. This is discussed below, under “B – Habitats.”
In addition to nutrient pollution, shrimp farms have been associated with a variety of other
discharges including antibiotics, herbicides, pesticides, piscicides and disinfectants. Information
about their impacts is scarce. Burgos-Hernandez et al. (2006) investigated the presence of
insecticides in and around a shrimp-farming area in Sonora. All the insecticides under
investigation were found in the water and sediment of the nearby estuary. Increasing regulatory
control on the use of chemicals is likely to reduce their use, but it is clear from the Comites de
Sanida Acuicola that at least antibiotics are regularly used in Mexican shrimp farms (one in five
farms in Sonora and nearly half of farms in the northern region of Sonora use antibiotics).
Burgos-Hernandez et al. (2006) concluded that it is likely that these figures are considerably
lower than many major shrimp producing nations.
In summary, Mexico’s farmed shrimp industry uses open shrimp ponds that discharge untreated
effluent directly into the environment during daily water exchange. There is substantial evidence
that the combined contributions of nutrients from agriculture, anthropological and aquaculture
sources are negatively impacting the Gulf of California. Although it is difficult to isolate the
impact of untreated effluent from 66,000 hectares of shrimp farms in Mexico from other sources,
the effluent represents a substantial source of nutrient enrichment and increased local
sedimentation. In addition, shrimp farming in Mexico continues to expand rapidly. Although
regional discharges may be relatively small compared to agriculture and other human activities,
researchers agree that shrimp-farm effluents contribute to the continued eutrophication of coastal
waters in the Gulf of California. For these reasons, pollution is considered a high conservation
concern for shrimp farms in Mexico.
B - Habitats
The Gulf of California hosts a unique set of habitats. Tropical mangrove forests and coral reefs
are found at the southern end, and a variety of intertidal habitats occur throughout the Gulf
(Lluch-Cota et al. 2007). Although much of the shoreline is rocky or sandy, at frequent intervals
the coast is indented with ‘negative estuaries’ (esteros or tidal lagoons) that tend to be saltier at
49
their headwaters than at their mouths due to a lack of freshwater inflow (Glenn et al. 2006).
These esteros are extensive in area due to the extreme tidal range of the northern Gulf of
California (5–10 m amplitude). Most of the esteros are above the mangrove line (28–29° N) and
are dominated by low-growing saltgrass and herbaceous and shrubby halophytes (Brusca et al.
2004). The esteros are the nursery grounds for larval development for wild shrimp and
commercial fish species.
Mexico had over 66,000 hectares of shrimp ponds in production in 2008. A large (but
undetermined) area of inactive or abandoned ponds also exists. As previously mentioned, most
of the farmed shrimp on the U.S. market from Mexico originates from one-cycle farms in Sonora
and northern Sinaloa. Despite having the greater production tonnage, Sonora has less than half
the area of ponds as Sinaloa (Table 2). Approximately 90% of the shrimp ponds are on coastal
land bordering the Gulf of California in the states of Sonora and Sinaloa. According to Mr.
Rodrigo De La Serna (Vice President of Operations for Ocean Gardens Products, Inc.) and Mr.
Ricardo Delgado (Ocean Gardens Products, Inc. Office Manager in Culiacan), approximately
90% of the Sonoran shrimp farms are surrounded by desert, and 10% are in areas with some
vegetation. The northern Sinaloan farms are located mainly in desert with some vegetation. A
shrimp farm in the desert area of Kino Bay, Sonora, is shown in Figure 16.
Figure 16. Shrimp farm ponds in Bahia Kino, Sonora. Photo from Ocean Gardens Products, Inc.
The destruction of mangrove forests (or other sensitive wetlands) for shrimp farming during the
construction, operation and expansion of shrimp farms has been, perhaps, the most controversial
aspect of the shrimp-farming industry’s rapid development. In general, mangrove forests and
wetlands are considered important for the following reasons (www.ramsar.org):
• Wetlands provide fundamental ecological services and are regulators of water regimes
and sources of biodiversity at all levels - species, genetic and ecosystem.
• Wetlands constitute a resource of great economic, scientific, cultural and recreational
value for a community.
50
•
•
Wetlands play a vital role in climate change adaptation and mitigation.
Progressive encroachment on, and loss of, wetlands cause serious and sometimes
irreparable environmental damage to the provision of ecosystem services.
The Gulf of California is the northernmost limit for the distribution of mangroves in the Eastern
Pacific (Contreras-Espinosa and Warner 2004). On the western coast of the Gulf of California,
mangroves are distributed from the Cape region to the center of the Baja California peninsula.
Mangroves exist primarily in small bays, estuaries and isolated mangrove pockets. On the
eastern side of the Gulf, mangrove forests are distributed in large coastal lagoons that show
extensive mangrove coverage from Tiburón Island in Sonora to Sinaloa and Nayarit. On the
Pacific side of the peninsula, the largest mangrove forests are found inside the coastal lagoons of
Magdalena Bay
The association between mangroves and shrimp farms in Mexico is not straight-forward. The
report by Valiela et al. (2001) states that mangrove cover in Mexico in 1983 was 6,600 km2 and
fell to 5,246 km2 in 1992. Over 9 years, Mexico experienced an estimated loss of 1,354 km2
(21%). The exact causes of these losses are not known. Although human population density is
low in the Gulf of California, there has been pressure to transform mangroves into shrimp farms
and tourist developments. Currently, mangroves are disappearing at a regional rate of 2%
annually due to sedimentation, eutrophication and deforestation (Aburto-Oropeza et al. 2008).
However, the administration of President Felipe Calderón, elected in late 2006 for a six-year
term, has reinstated the ban on developing mangroves in Mexico (Arizona-Sonora Desert
Museum Department of Conservation and Science, R. Brusca, pers. comm., 21 June, 2009). This
action restricts the construction of new shrimp farms within mangrove esteros. In Sonora, there is
at least one large inland farm on previously degraded agricultural land (Arizona-Sonora Desert
Museum Department of Conservation and Science, R. Brusca, pers. comm., 26 June 2009).
Figure 17 shows areas of mangrove forest (in green), and Figure 15 shows RAMSAR nominated
sites for the same area. The RAMSAR Convention on Wetlands was signed by Mexico on 4
November 1986, and there are currently 112 sites designated as Wetlands of International
Importance in Mexico. These areas comprise a surface area of 8,118,927 hectares.
51
Figure 17. Map of the Gulf of California with mangrove areas marked in green (from Aburto-Oropeza et al.
2008). Red areas are the 13 fishery regions, black dots represent National Fisheries offices (CONAPESCA).
Figure 17 shows many mangrove areas on the northwest coast of Mexico in Sonora, and
particularly in Sinaloa and Nayarit. Figure 18 shows that a number of RAMSAR-designated sites
are located in Sinaloa, but there are none in the dominant production state of Sonora. However,
over 60% of Mexico’s shrimp ponds, in terms of area, are located in Sinaloa. The RAMSAR
Convention on Wetlands is an intergovernmental treaty that provides the framework for national
action and international cooperation for the conservation and wise use of wetlands and their
resources. Mexico signed the treaty in 1986.
52
Figure 18. RAMSAR sites in the Gulf of California. Map from www.ramsar.org, 2009.
Glenn et al. (2006) reports over 95% of the mangrove marshes in Mexico have been developed
for shrimp farming. In most cases, the farms are built adjacent to, rather than in, the marshes, and
the mangrove stands are still mostly intact. Some destruction of mangroves has been reported
(Meling-Lopez et al. 2004), however, in nearly all cases the shrimp farms have been located
adjacent to, rather than within, the mangrove stands and there has been little net loss of
mangrove stands thus far. Federal legal restrictions on the clearing of mangrove forests are
responsible for this outcome. Additionally, pond construction and management are easier on the
flats than in the mangrove marshes themselves (Glenn et al. 2006). A similar development
pattern has taken place in the mangrove esteros of southern Sonora, Sinaloa and Nayarit.
However, mangrove forests can be impacted in ways other than by direct clearance. Mangrove
esteros in the Gulf of California that have shrimp ponds nearby have been damaged by several
indirect impacts, including altered hydrological patterns, hypersalinity and eutrophication (PáezOsuna et al. 2003). The system of ponds, roads and levees at the back of the esteros reduces the
ability of freshwater flows (rainfall, streams and springs) to penetrate into the intertidal zone.
Furthermore, the seawater in aquaculture ponds induces seawater intrusion that raises the salinity
level at the backs of the marshes. As a result, the marsh may become hypersaline, reducing the
vigor of the mangrove forests. In some cases, hypersaline conditions lead to die-offs of white
mangroves, which cannot tolerate continuous high-salinity conditions. In addition, eutrophication
53
can occur through the discharge of shrimp-pond effluent into the estero, or along the adjacent
coastline. Eutrophication may not directly affect the mangroves, but it affects the periphyton and
prop root communities at the base of the food chain, and the excess nutrients (and added
chemicals and exotic pathogens) are discharged into the open environment (Glenn et al. 2006
and references therein).
Although it appears that relatively few areas of mangrove have been physically cleared or
destroyed for shrimp pond construction, mangrove forests adjacent to shrimp farms can still be
impacted. The lands adjacent to mangroves are halophyte-dominated wetlands containing
halophytes endemic to the Gulf of Mexico region (Sonora Desert Museum Department of
Conservation and Science, R. Brusca, pers. comm., 26 June 2009). For example, the RAMSAR
site report for Laguna Playa Colorada-Santa María La Reforma in Sinaloa (RAMSAR site no.
1340), states that there are over 10,000 ha of shrimp farms have resulted in many environmental
impacts, such as silting, pollution with pesticides, spread of viruses from farmed to wild
populations, drying up of nearly 10% of the mangroves and disruption of the hydrological flows.
In addition, shrimp farms are often located in other sensitive habitat types. All of Mexico’s
shrimp farms have been built in or next to coastal wetlands, which have a high conservation
value. It appears that shrimp farms in Mexico are more likely to negatively impact wetlands and
esteros rather than have direct impacts on mangrove forests. The saltgrass and estuarine habitats
in the Gulf of California are ecologically important habitats.
Glenn et al. (2006 and references therein) concluded:
Our working hypothesis, is that these esteros might have great, if unrecognized,
importance to the marine food chain and to the movement of water birds and terrestrial
neotropical birds along the desert coastline in the northern gulf. Based on our initial
observations, the human impact on the esteros at current levels appear to be manageable.
Aquaculture and tourism development has, for the most part, not taken place directly
within the esteros, but adjacent to them. Unlike the mangrove marshes, it is still
permissible to convert saltgrass marshes to shrimp ponds and marinas, or to fill them in
for resort development. The saltgrass marshes should be given the same degree of
protection as the mangrove marshes, as they fulfill many of the same ecological functions
and there is no protection for this marsh type.
Although Glenn et al. (2006) did not observe human impacts on esteros during their study,
shrimp farms continue to expand rapidly and discharge effluent into Mexican esteros, including
local impacts that have been recorded by L. Meltzer in the area between Bahia Kino and Estero
Tastiota.
Alonso-Perez et al. (2003) studied the Ceuta lagoon in Sinaloa, and reported the following:
Although shrimp farming has been reported as the principal cause of worldwide
mangrove reduction, and construction of shrimp ponds around the Ceuta coastal lagoon
have changed land uses, they have had a minimal effect on mangrove coverage. Shrimp
farming represents less than 1% of the total surface in the studied area, but is equivalent
to one-third of the estimated lagoon system surface (9300 ha). Instead of using mangrove
areas, shrimp farming has used areas formerly occupied by temporary agriculture and
54
zones of bare substratum, including salt marsh, a cover that acts as an interconnection
between wetland systems during tidal floods. Thus, shrimp pond construction is not
acting directly on the mangrove forest coverage, but can alter the system dynamics,
interrupting the continuity of natural events such as local dispersion and migration of
vegetal and animal species, and modifying the local hydrology. Equilibrium between
sedimentation and coastal submersion rates determines the stability in salt marsh systems
and, because shrimp ponds are growing on these environments, salt marsh systems are
not only losing surface by land use changes, but probably pond and channel construction
have an effect on the natural hydrology of salt marshes. Modifications of overland flow,
tidal drainage, and natural patterns of flooding, sedimentation and accretion are some of
the main effects caused by construction of shrimp-farming infrastructure. Salt marsh
areas of Sinaloa have been selected as the most suitable sites for shrimp pond settlement,
because despite their natural productivity they are thought of as economically
unproductive areas and are considered low-value properties. However, these
environments play an important role in coastal ecosystems, supporting wildlife, trapping
sediments and nutrients, diminishing flooding risks, and helping in water storage. An
increase in the area of shrimp ponds, without prior knowledge of the natural channels of
communication among wetlands, puts the natural production of the system at high risk by
reducing wetland areas and the connectivity among them.
Synthesis
Effluent from shrimp farms has the potential to negatively impact the environment at the local
scale due to nitrification, sedimentation and changes in hydrology. With daily water exchanges
of 10-30% (or more), the concentration of pollutants in the effluent water is likely to be low.
However, the volume of effluent discharge is high and the system is considered to be open in this
regard. The level of nutrients being discharged untreated from shrimp farms into the Gulf of
California is substantial and is estimated to be equivalent to the nutrient content of untreated
sewage from 1.9 million people per year. Researchers who have studied shrimp-farm outputs
suggest that the large volume of nutrients and sediments discharged has negative local effects,
particularly to esteros. Effluent from shrimp farms also contributes to regional problems
associated with increasing nutrient input to the greater Gulf of California, which is experiencing
increasing environmental problems, such as Harmful Algal Blooms (HABs).
Nutrient enrichment from the combined sources of agriculture, municipal waste and aquaculture
cause negative regional impacts in the Gulf of California. It does not appear that Mexican shrimp
farming is the major contributor to these impacts, but it appears that untreated shrimp-farm
effluent is a substantial source of nutrient enrichment. In addition, the shrimp-farming industry
continues to grow rapidly in Mexico.
Almost all of Mexico’s shrimp farms are located in sheltered coastal habitats. The Gulf of
California coastal environment hosts a unique set of habitats and is considered to be an
environment of high conservation status. The great majority of Mexican shrimp farms in Sonora,
Sinaloa and Nayarit interact with these sensitive coastal environments. The interaction of shrimp
farms with these habitats types, particularly mangrove forests, has been the subject of
considerable controversy on a global scale. The bulk of Mexican shrimp production, in terms of
55
tonnage, occurs in Sonora. However, the bulk of shrimp ponds, in terms of area, occurs in
Sinaloa and Nayarit. Sinaloa and Nayarit are to the south of Sonora, where more extensive
wetlands and mangrove forest occur. A number of protected RAMSAR wetland sites are located
in Sinaloa. Although 95% of the Gulf of California’s mangrove-associated lagoons have been
developed for shrimp farming, there is minimal documentation regarding the potential direct
impacts from farm construction. Despite the fact that relatively few mangrove-forested areas
have actually been cleared for ponds, most ponds have destroyed or impacted adjacent wetlands
and tidal/salt marsh habitats. Additionally, many (perhaps most) farms drain directly into the
mangrove lagoons. The tidal marsh habitats of the Gulf are threatened wetlands that contain a
diversity of plant and animal life, much of which is unique and endemic to this habitat. It is well
known from studies around the world that shrimp-farm operations can also have other negative
impacts on mangrove forests or other sensitive habitats, particularly from pond effluent. Due to
Mexico’s use of sensitive coastal habitats for most shrimp farms and the rapid expansion in total
pond area, the risk to habitats is considered a high conservation concern.
Overall, there are several factors that represent a high concern for this criterion, including
discharge of untreated effluent via daily water exchange, local habitat impacts and siting of
ponds in areas of ecological sensitivity. Under these circumstances, the continued expansion of
shrimp farms into sensitive coastal, wetland and estuarine habitats is a high conservation concern
for this criterion.
Risk of Pollution and Habitat Effects Rank:
Low
Moderate
High
Criterion 5: Effectiveness of the Management Regime
Guiding Principle: The management regime of sustainable aquaculture operations respects all
local, national and international laws and utilizes a precautionary approach, which favors the
conservation of the environment, for daily operations and industry expansion.
Factors:
• Demonstrated application of existing laws
• Use of licensing to control the location, number, size and stocking density of farms
• Effectiveness of “better management practices,” especially to reduce escaped shrimp
• Effectiveness of measures to prevent and treat disease outbreaks
• Existence of regulations for therapeutants
• Use and effect of predator controls
• Existence of a precautionary approach to guide industry expansion
The main aquaculture regulation in Mexico, the Law on Sustainable Fisheries and Aquaculture,
was established in 2007 (Ley General de Pesca y Acuacultura Sustenables). In addition, Juarez
(2008) provides the following summary of the regulatory framework in Mexico:
56
In Mexico, shrimp aquaculture falls within the regulatory framework of two departments
at the ministerial level, the Department of Agriculture (SAGARPA), and the Department
of Natural Resources and Environment (SEMARNAT). Under Agriculture (SAGARPA)
there are three agencies most concerned with aquaculture:
1) The National Commission of Aquaculture and Fisheries (CONAPESCA) deals
primarily with operating permits.
2) The National Service of Alimentary Health, Quality and Innocuity (SENASICA) is in
charge of animal health.
3) The National Fisheries Institute (INP) provides research and technical opinions.
Under Environment (SEMARNAT) there are four agencies involved:
1) The Directorate of Environmental Impact, which reviews environmental impact
statements, sets operating restrictions and evaluates environmental permits.
2) The National Water Commission (CNA) regulates water use and discharges.
3) The Directorate of Federal Zoning, which regulates uses of the Federal Coastal Zone.
4) The Environmental Protection Attorney’s Office (PROFEPA), which enforces
environmental regulations.
In the last 4 years, new agencies called State Committees of Aquaculture Health have
been operating under a cooperative agreement between producers as well as the state and
federal governments. These committees have been instrumental at regulating disease
certification, stocking dates and sanitary practices; they also keep precise statistics on the
industry.
The committees referred to above (Juarez 2008) are the Comites de Sanidad Acuícola. They
were set up in cooperation with SENASICA (Servicio Nacional de Sanidad, Inocuidad y Calidad
Agroalimentaria). The Committees include representatives from academia, state government and
federal government. Shrimp farmers must join their state committees and comply with the
aquatic health regulations (Rosenberry 2008). Much of the production data in this report was
obtained from the various websites of each state’s committee.
In addition to national regulations, individual states may also have their own regulations. Sonora
has the following additional regulations:
•
•
•
Law of fishing and aquaculture for the state of Sonora (Ley de Pesca y Acuicultura para
el Estado de Sonora),
Regulation of the Law of Aquaculture for the State of Sonora (Reglamento de la Ley de
Acuicultura para el Estado de Sonora),
Sanitary protocol for Sonora shrimp farms (Protocolo Sanitario 2005 para las Juntas
Locales de Sanidad Acuicola).
Additionally, Sonora has established a best practice scheme. Figure 19 shows the level of
compliance (% de cumplimiento) with the scheme.
57
Figure 19. Compliance with Sonora’s Best Practice scheme (from COSAES 2009). “% de Cumplimiento”
stands for level of compliance, “cumple” stands for meets the standards, “norte” is north, “centro” is central
and “sur” is south.
Dr. Albert Vanderheiden of the Centro de Investigación en Alimentación y Desarrollo (CIAD)
provided information and an expert opinion regarding the management practices for the state of
Sinaloa (pers. comm., 23 July 2009). CIAD translated loosely means the Center for the Study of
Nutrition and Growth. Dr. Vanderheiden states that environmentally friendly practices have
improved because there is greater control of antibiotics. Additionally, the use of prophylactics is
rare. In addition, feeds are better balanced, and improvements in feed administration lead to less
waste and nutrient runoff to the esteros. CIAD has worked well with the shrimp farmers,
educating them regarding "buenas practicas de producción" (better management practices), and
there has been improved knowledge and prevention of viral and bacterial diseases. According to
Kino Bay Mexico Center, the farmers in the region between Bahia Kino and Estero Tastiota are
successful at self-regulation for disease protection within the farm (L. Meltzer, pers. comm., 4
September 2009). Dr. Vanderheiden notes that in general farmers have increasing respect for
mangroves. Mangrove "soil" is inadequate for the construction of ponds and farmers avoid
mangroves because they contain so many shrimp predators.
However, efforts to control pollution from shrimp farms do not appear to be effective. According
to Dr. Vanderheiden, Although CIAD’s farm education programs insist on the use of oxidation
ponds, Dr. Vanderheiden suggests that the farmers resist treating their wastewater and continue
to discharge directly into the sea or the esteros because designating ponds for wastewater
treatment decreases the number that can be used to grow shrimp (pers. comm., 23 July 2009).
Lorayne Meltzer of Kino Bay Mexico Center states that consistent water quality testing is not a
common practice (pers. comm., 4 September 2009), and Páez-Osuna et al. (2003) report that the
low regulatory effectiveness for shrimp farming is problematic for the water quality in the Gulf
of California.
Despite biosecurity and better management practices or regulations, the continued disease
occurrence on Mexican shrimp farms and the daily water exchange with the Gulf of California,
continue to cause concern for pathogen transfer to wild stocks.
58
Synthesis
The regulatory structure for aquaculture in Mexico appears robust. The creation of COSAES for
increased disease management is encouraging and somewhat unique in the industry. Despite the
continuing and increasing water quality problems present in the Gulf of California (e.g.,Harmful
Algal Blooms), untreated effluent is still discharged from shrimp farms. This issue is not being
addressed adequately. These factors suggest a moderate conservation concern for management
effectiveness.
Effectiveness of Management Rank:
Low
Moderate
59
High
IV. Overall Evaluation and Seafood Ranking
Table of Sustainability Ranks
Sustainability Criteria
Conservation Concern
Moderate
High
Low
Critical
√
√
Use of Marine Resources
Risk of Escaped Fish to Wild
Stocks
Risk of Disease and Parasite
Transfer to Wild Stocks
Risk of Pollution and Habitat
Effects
Management Effectiveness
√
√
√
About the Overall Seafood Recommendation:
•
•
•
A species receives a recommendation of “Best Choice” if:
1) It has three or more green criteria and the remaining criteria are not red.
A species receives a recommendation of “Good Alternative” if:
1) Criteria “average” to yellow
2) There are four green criteria and one red criterion
A species receives a recommendation of “Avoid” if:
1) It has a total of two or more red criteria
2) It has one or more Critical Conservation Concerns.
Overall Seafood Recommendation:
Best Choice
Good Alternative
Avoid
There do not appear to be any Mexican shrimp farms currently approved by independent
certification schemes such as the Global Aquaculture Alliance’s Best Management Practice
standards, GlobalGAP, Organic, the BAP (Better Aquaculture Practices) program in Mexico,
MéxicoGAP, or any other widely-recognized scheme that might help to identify better practices
among Mexican shrimp producers. Additionally, it does not appear that the “Mexico Calidad
Suprema” label has been benchmarked with BAP or GlobalGAP standards for shrimp farms.
An important improvement to the industry in Mexico would be effluent treatment to help
mitigate the risk of disease retransmission to wild stocks, and to reduce the amount of nutrients
and sediments being discharged to coastal and estuarine waters via high daily water exchange
rates. Researchers consistently report that nutrient inputs to the Gulf of California are causing
increasing environmental damage. CIAD (Center for the Study of Nutrition and Growth)
60
recommends the use of oxidation ponds in Mexico, but notes that farmers continue to resist this
better management practice. Effluent discharge from shrimp farms represents a point source of
pollution that can be monitored and regulated. The overall ranking could improve to “Good
Alternative” if there is consistent monitoring of shrimp farm effluents, water quality standards
are met for these effluents and if shrimp farmers ‘closed’ their ponds to the external environment
(a management method now widespread in SE Asia).
Acknowledgements
Scientific review does not constitute an endorsement of the Seafood Watch® program, or its
seafood recommendations, on the part of the reviewing scientists. Seafood Watch® is solely
responsible for the conclusions reached in this report. Seafood Watch is grateful for the expert
reviewers who made many contributions to this report. Reviewers included Dr. Richard Brusca,
Senior Director of Conservation and Science at the Arizona-Sonora Desert Museum and a
Research Scientist at the University of Arizona; Ms. Lorayne Meltzer, Co-Director of the Kino
Bay Mexico Center and faculty member of the Environmental Studies at Prescott College, who
has been conducting field research on Mexican shrimp farms since 2000; and also an anonymous
reviewer.
61
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Appendix II. Aquaculture Evaluation of Mexico farmed shrimp
Species: Litopenaeus vannamei Region: MEXICO Aquaculture Evaluation
Seafood Watch™ defines sustainable seafood as from sources, whether fished or farmed, that can
maintain or increase production into the long-term without jeopardizing the structure or function of
affected ecosystems.
The following guiding principles illustrate the qualities that aquaculture operations must possess to
be considered sustainable by the Seafood Watch program. Sustainable aquaculture:
• uses less wild caught fish (in the form of fish meal and fish oil) than it produces in the form of edible marine fish protein, and thus provides net protein gains for society; • does not pose a substantial risk of deleterious effects on wild shrimp stocks through the escape of farmed shrimp3; • does not pose a substantial risk of deleterious effects on wild shrimp stocks through the amplification, retransmission or introduction of disease or parasites; • employs methods to treat and reduce the discharge of organic waste and other potential contaminants so that the resulting discharge does not adversely affect the surrounding ecosystem; and • implements and enforces all local, national and international laws and customs and utilizes a precautionary approach (which favors conservation of the environment in the face of irreversible environmental risks) for daily operations and industry expansion. Seafood Watch has developed a set of five sustainability criteria, corresponding to these guiding
principles, to evaluate aquaculture operations for the purpose of developing a seafood
recommendation for consumers and businesses. These criteria are:
1. Use of marine resources
2. Risk of escapes to wild stocks
3. Risk of disease and parasite transfer to wild stocks
4. Risk of pollution and habitat effects
5. Effectiveness of the management regime
Each criterion includes:
• Primary factors to evaluate and rank
• Secondary factors to evaluate and rank
• Evaluation guidelines4 to synthesize these factors
• A resulting rank for that criterion
3
“Fish” is used throughout this document to refer to finfish, shellfish and other farmed invertebrates.
Evaluation Guidelines throughout this document reflect common combinations of primary and secondary factors
that result in a given level of conservation concern. Not all possible combinations are shown – other combinations
should be matched as closely as possible to the existing guidelines.
4
69
Once a rank has been assigned to each criterion, an overall seafood recommendation for the type of
aquaculture in question is developed based on additional evaluation guidelines. The ranks for each
criterion, and the resulting overall seafood recommendation, are summarized in a table.
Criteria ranks and the overall recommendation are color-coded to correspond to the categories on
the Seafood Watch pocket guide:
Best Choices/Green: Consumers are strongly encouraged to purchase seafood in this category. The
aquaculture source is sustainable as defined by Seafood Watch.
Good Alternatives/Yellow: Consumers are encouraged to purchase seafood in this category, as they
are better choices than seafood from the Avoid category. However, there are some concerns with
how this species is farmed and thus it does not demonstrate all of the qualities of sustainable
aquaculture as defined by Seafood Watch.
Avoid/Red: Consumers are encouraged to avoid seafood from this category, at least for now.
Species in this category do not demonstrate enough qualities to be defined as sustainable by Seafood
Watch.
70
CRITERION 1: USE OF MARINE RESOURCES Guiding Principle: To conserve ocean resources and provide net protein gains for society, aquaculture operations should use less wild‐caught fish (in the form of fish meal and fish oil) than they produce in the form of edible marine fish protein. Feed Use Components to Evaluate
A) Yield Rate: Amount of wild‐caught fish (excluding fishery by‐products) used to create fish meal and fish oil (ton/ton): ¾ Wild Fish: Fish Meal; Enter ratio = 4.5 [i.e. value = 4.5:1 from Tyedmers (2000)5] ¾ Wild Fish: Fish Oil; Enter ratio: 8.3 [i.e. value = 8.3:1 from Tyedmers (2000)] B) Inclusion rate of fish meal, fish oil, and other marine resources in feed (%): ¾ Fish Meal; Enter % = 16.0 ¾ Fish Oil; Enter % = 3.0 C) Efficiency of Feed Use: Known or estimated average economic Feed Conversion Ratio (FCR = dry
feed:wet shrimp) in grow-out operations:
¾ Enter FCR here = 2.3 COSAES Wild Input:Farmed Output Ratio (WI:FO)
Calculate and enter the larger of two resultant values: ¾ Meal: [Yield Rate]meal x [Inclusion rate]meal x [FCR] = 4.5 x 0.16 x 2,3 = 1.7 ¾ Oil: [Yield Rate]oil x [Inclusion rate]oil x [FCR] = 8.3 x 0.03 x 2.3 = 0.6 ¾ WI:FO = 1.7 Primary Factor (WI:FO)
Estimated wild fish used to produce farmed shrimp (ton/ton, from above): ¾ Low Use of Marine Resources (WI:FO = 0 ‐ 1.1) OR supplemental feed not used ¾ Moderate Use of Marine Resources (WI:FO = 1.1 ‐ 2.0) ¾ Extensive Use of Marine Resources (WI:FO > 2.0) 5
Tyedmers (2000): Salmon and sustainability: The biophysical cost of producing salmon through the commercial
salmon fishery and the intensive salmon culture industry. PhD Thesis. The University of British Columbia. 272
pages.
71
Secondary Factors
Stock status of the reduction fishery used for feed for the farmed species: ¾ At or above BMSY (> 100%) ¾ Not applicable because supplemental feed not used ¾ Moderately below BMSY (50 ‐ 100%) OR Unknown ¾ Substantially below BMSY (e.g. < 50%) OR Overfished OR Overfishing is occurring OR fishery is unregulated Source of stock for the farmed species: ¾ Stock from closed life cycle hatchery OR wild caught and intensity of collection clearly does not result in depletion of brood stock, wild juveniles or associated non‐target organisms ¾ Wild caught and collection has the potential to impact brood stock, wild juveniles or associated non‐target organisms ¾ Wild caught and intensity of collection clearly results in depletion of brood stock, wild juveniles, or associated non‐target organisms Evaluation Guidelines
Use of marine resources is “Low” when WI:FO is between 0.0 and 1.1. Use of marine resources is “Moderate” when WI:FO is between 1.1 and 2.0. Use of marine resources is “Extensive” when: 1. WI:FO is greater than 2.0 2. Source of stock for the farmed species is ranked red 3. Stock status of the reduction fishery is ranked red Use of marine resources is deemed to be a Critical Conservation Concern and a species is ranked Avoid, regardless of other criteria, if: 1. WI:FO is greater than 2.0 AND the source of seed stock is ranked red. 2. WI:FO is greater than 2.0 AND the stock status of the reduction fishery is ranked red Conservation Concern: Use of Marine Resources
Low (Low Use of Marine Resources) Moderate (Moderate Use of Marine Resources) High (Extensive Use of Marine Resources) Critical Use of Marine Resources
72
CRITERION 2: RISK OF ESCAPED SHRIMP TO WILD STOCKS Guiding Principle: Sustainable aquaculture operations pose no substantial risk of deleterious effects to wild shrimp stocks through the escape of farmed shrimp. Primary Factors to evaluate
Evidence that farmed shrimp regularly escape to the surrounding environment ¾ Rarely if system is open OR never because system is closed ¾ Infrequently if system is open OR Unknown ¾ Regularly and often in open systems Status of escaping farmed shrimp to the surrounding environment ¾ Native and genetically and ecologically similar to wild stocks OR survival and/or reproductive capability of escaping farmed species is known to be naturally zero or is zero because of sterility, polyploidy or similar technologies ¾ Non‐native but historically widely established OR Unknown ¾ Non‐native (including genetically modified organisms) and not yet fully established OR native and genetically or ecologically distinct from wild stocks Secondary Factors to evaluate
Where escaping shrimp is non-native – Evidence of the establishment of
self-sustaining feral stocks
¾ Studies show no evidence of establishment to date ¾ Establishment is probable on theoretical grounds OR Unknown ¾ Empirical evidence of establishment Where escaping shrimp is native – Evidence of genetic introgression through successful crossbreeding ¾ Studies show no evidence of introgression to date ¾ Introgression is likely on theoretical grounds OR Unknown ¾ Empirical evidence of introgression ¾ Spawning disruption is likely on theoretical grounds OR Unknown ¾ Empirical evidence of spawning disruption Evidence of spawning disruption of wild shrimp ¾ Studies show no evidence of spawning disruption to date 73
Evidence of competition with wild shrimp for limiting resources or habitats ¾ Studies show no evidence of competition to date ¾ Competition is likely on theoretical grounds OR Unknown ¾ Empirical evidence of competition Stock status of affected wild shrimp ¾ At or above (> 100%) BMSY OR no affected wild shrimp ¾ Moderately below (50 – 100%) BMSY OR Unknown ¾ Substantially below BMSY (< 50%) OR Overfished OR “endangered”, “threatened” or “protected” under state, federal or international law Evaluation Guidelines
A “Minor Risk” occurs when a species: 1) Never escapes because system is closed 2) Rarely escapes AND is native and genetically/ecologically similar. 3) Infrequently escapes AND survival is known to be nil. A “Moderate Risk” occurs when the species: 1) Infrequently escapes AND is non‐native and not yet fully established AND there is no evidence to date of negative interactions. 2) Regularly escapes AND native and genetically and ecologically similar to wild stocks or survival is known to be nil. 3) Is non‐native but historically widely established. A “Severe Risk” occurs when: 1) The two primary factors rank red AND one or more additional factor ranks red. Risk of escapes is deemed to be a Critical Conservation Concern and a species is ranked Avoid, regardless of other criteria, when: 1) Escapes rank a “severe risk” AND the status of the affected wild shrimp also ranks red. Conservation Concern: Risk of Escaped Shrimp to Wild Stocks
Low (Minor Risk) Moderate (Moderate Risk) High (Severe Risk) Critical Risk 74
CRITERION 3: RISK OF DISEASE AND PARASITE TRANSFER TO WILD STOCKS Guiding Principle: Sustainable aquaculture operations pose little risk of deleterious effects to wild shrimp stocks through the amplification, retransmission or introduction of disease or parasites. Primary Factors to evaluate
Risk of amplification and retransmission of disease or parasites to wild stocks ¾ Studies show no evidence of amplification or retransmission to date ¾ Likely risk of amplification or transmission on theoretical grounds OR Unknown ¾ Empirical evidence of amplification or retransmission Risk of species introductions or translocations of novel disease/parasites to wild
stocks
¾ Studies show no evidence of introductions or translocations to date ¾ Likely risk of introductions or translocations on theoretical grounds OR Unknown ¾ Empirical evidence of introductions or translocations Secondary Factors to evaluate
Bio‐safety risks inherent in operations ¾ Low risk: Closed systems with controls on effluent release ¾ Moderate risk: Infrequently discharged ponds or raceways OR Unknown ¾ High risk: Frequent water exchange OR open systems with water exchange to outside environment (e.g. nets, pens or cages) Stock status of potentially affected wild shrimp
¾ At or above (> 100%) BMSY OR no affected wild shrimp ¾ Moderately below (50 – 100%) BMSY OR Unknown ¾ Substantially below BMSY (< 50%) OR Overfished OR “endangered”, “threatened” or “protected” under state, federal or international law 75
Evaluation Guidelines
Risk of disease transfer is deemed “Minor” if: 1) Neither primary factor ranks red AND both secondary factors rank green. 2) Both primary factors rank green AND neither secondary factor ranks red Risk of disease transfer is deemed to be “Moderate” if the ranks of the primary and secondary factors “average” to yellow. Risk of disease transfer is deemed to be “Severe” if: 1) Either primary factor ranks red AND bio‐safety risks are low or moderate. 2) Both primary factors rank yellow AND bio‐safety risks are high AND stock status of the wild fish does not rank green. Risk of disease transfer is deemed to be a Critical Conservation Concern and a species is ranked Avoid regardless of other criteria, if either primary factor ranks red AND stock status of the wild shrimp also ranks red. Conservation Concern: Risk of Disease Transfer to Wild Stocks
Low (Minor Risk) Moderate (Moderate Risk) High (Severe Risk) Critical Risk 76
CRITERION 4: RISK OF POLLUTION AND HABITAT EFFECTS
Guiding Principle: Sustainable aquaculture operations employ methods to treat and reduce the discharge of organic effluent and other potential contaminants so that the resulting discharge and other habitat impacts do not adversely affect the integrity and function of the surrounding ecosystem. Primary Factors to evaluate
PART A: Effluent Effects
Effluent water treatment ¾ Effluent water substantially treated before discharge (e.g. recirculating system, settling ponds, or reconstructed wetlands) OR polyculture and integrated aquaculture used to recycle nutrients in open systems OR treatment not necessary because supplemental feed is not used ¾ Effluent water partially treated before discharge (e.g. infrequently flushed ponds) ¾ Effluent water not treated before discharge (e.g. open nets, pens or cages) Evidence of substantial local (within 2 x the diameter of the site) effluent effects (including altered benthic communities, presence of signature species, modified redox potential, etc) ¾ Studies show no evidence of negative effects to date ¾ Likely risk of negative effects on theoretical grounds OR Unknown ¾ Empirical evidence of local effluent effects Evidence of regional effluent effects (including harmful algal blooms, altered nutrient
budgets, etc)
¾ Studies show no evidence of negative effects to date ¾ Likely risk of negative effects on theoretical grounds OR Unknown ¾ Empirical evidence of regional effluent effects ¾ Effects are in compliance with set standards ¾ Effects infrequently exceed set standards ¾ Effects regularly exceed set standards Extent of local or regional effluent effects 77
Part B: Habitat Effects
Potential to impact habitats: Location ¾ Operations in areas of low ecological sensitivity (e.g. land that is less susceptible to degradation, such as formerly used agriculture land or land previously developed) ¾ Operations in areas of moderate sensitivity (e.g. coastal and near‐shore waters, rocky intertidal or subtidal zones, river or stream shorelines, offshore waters) ¾ Operations in areas of high ecological sensitivity (e.g. coastal wetlands, mangroves) Potential to impact habitats: Extent of Operations ¾ Low density of shrimp/site or sites/area relative to flushing rate and carrying capacity in open systems OR closed systems ¾ Moderate densities of shrimp/site or sites/area relative to flushing rate and carrying capacity for open systems ¾ High density of shrimp/site or sites/area relative to flushing rate and carrying capacity for open systems Evaluation Guidelines
Risk of pollution/habitat effects is “Low” if three or more factors rank green and none of the other factors are red. Risk of pollution/habitat effects is “Moderate” if factors “average” to yellow. Risk of pollution/habitat effects is “High” if three or more factors rank red. No combination of ranks can result in a Critical Conservation Concern for Pollution and Habitat Effects. Conservation Concern: Risk of Pollution and Habitat Effects
Low (Low Risk) Moderate (Moderate Risk) High (High Risk) 78
CRITERION 5: EFFECTIVENESS OF THE MANAGEMENT REGIME
Guiding Principle: The management regime of sustainable aquaculture operations respects all local, national and international laws and utilizes a precautionary approach, which favors the conservation of the environment, for daily operations and industry expansion. Primary Factors to evaluate
Demonstrated application of existing federal, state and local laws to current aquaculture operations ¾ Yes, federal, state and local laws are applied ¾ Yes but concerns exist about effectiveness of laws or their application ¾ Laws not applied OR laws applied but clearly not effective Use of licensing to control the location (siting), number, size and stocking density of farms ¾ Yes and deemed effective ¾ Yes but concerns exist about effectiveness ¾ No licensing OR licensing used but clearly not effective Existence and effectiveness of “better management practices” for aquaculture operations, especially to reduce escaped shrimp ¾ Exist and deemed effective ¾ Exist but effectiveness is under debate OR Unknown ¾ Do not exist OR exist but clearly not effective Existence and effectiveness of measures to prevent disease and to treat those outbreaks that do occur (e.g. vaccine program, pest management practices, fallowing of pens, retaining diseased water, etc.) ¾ Exist and deemed effective ¾ Exist but effectiveness is under debate OR Unknown ¾ Do not exist OR exist but clearly not effective Existence of regulations for therapeutants, including their release into the environment, such as antibiotics, biocides, and herbicides ¾ Exist and deemed effective OR no therapeutants used ¾ Exist but effectiveness is under debate, or Unknown ¾ Not regulated OR poorly regulated and/or enforced 79
Use and effect of predator controls (e.g. for birds and marine mammals) in farming operations ¾ Predator controls are not used OR predator deterrents are used but are benign ¾ Predator controls used with limited mortality or displacement effects ¾ Predator controls used with high mortality or displacement effects Existence and effectiveness of policies and incentives, utilizing a precautionary
approach (including ecosystem studies of potential cumulative impacts) against
irreversible risks, to guide expansion of the aquaculture industry
¾ Exist and are deemed effective ¾ Exist but effectiveness is under debate ¾ Do not exist OR exist but are clearly ineffective Evaluation Guidelines
Management is “Highly Effective” if four or more factors rank green and none of the other factors rank red. Management is “Moderately Effective” if the factors “average” to yellow. Management is deemed to be “Ineffective” if three or more factors rank red. No combination of factors can result in a Critical Conservation Concern for Effectiveness of Management. Conservation Concern: Effectiveness of the Management Regime
Low (Highly Effective) Moderate (Moderately Effective) High (Ineffective) 80
Overall Seafood Recommendation Overall Guiding Principle: Sustainable farm-raised seafood is grown and harvested in ways can maintain
or increase production in the long-term without jeopardizing the structure or function of affected
ecosystems.
Evaluation Guidelines
A species receives a recommendation of “Best Choice” if: 1) It has three or more green criteria and the remaining criteria are not red. A species receives a recommendation of “Good Alternative” if: 1) Criteria “average” to yellow 2) There are four green criteria and one red criteria A species receives a recommendation of “Avoid” if: 1) It has a total of two or more red criteria 2) It has one or more Critical Conservation Concerns. Sustainability Criteria Summary of Criteria Ranks
Conservation Concern Low Moderate High Critical Use of Marine Resources Risk of Escapes to Wild Stocks Risk of Disease/Parasite Transfer to Wild Stocks Risk of Pollution and Habitat Effects Effectiveness of Management Overall Seafood Recommendation
Best Choice Good Alternative Avoid 81
ANNEX II – Public Data from Comité Sanidad Acuícola del Estado de Sonora, AC on
Hatcheries
A list of websites for various aquaculture health committees in Mexico for the major shrimp farming states (see Figure 6). More details are available at http://www.cesasin.com.mx/VINCULOS%20COMITES.html Sonora COSAES Comité de Sanidad Acuícola del Estado de Sonora. A.C. http://www.cosaes.com/ Sinaloa CESASIN Comité Estatal de Sanidad Acuícola de Sinaloa A.C. http://www.cesasin.com.mx/ Nayarit (CESANAY) Comité Estatal de Sanidad Acuícola del Estado de Nayarit, A.C. http://www.cesanay.com/quienessomos.html Baja California South CESABCS Comité de Sanidad Acuícola de Baja California Sue A.C. http://www.cesabcs.org/index‐2.html Tamaulipas CESATAM Comité de Sanidad Acuícola del Estado de Temaulipas A.C. http://www.cesatam.com/ Baja California El Comité Estatal de Sanidad Acuícola e Inocuidad de Baja California (CESAIBC). http://www.cesaibc.org/ Jalisco CESAJ Comité Estatal de Sanidad Acuícola de Jalisco www.cesaj.org Colima CESACOL Comité Estatal de Sanidad Acuícola del Estado de Colima http://cesacol.com/ 82