Download SHRIMP TRAWLER BY-CATCH DIVERSITY AND

PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACTS STUDIES
Background: The shrimp fishery is the
most important fishery in Mexico in terms of
value, exports, and employment. In 2008, the
Mexican shrimp fishery landed 196,289 metric
tons (MT) of shrimp. Sonora produces more
shrimp than any other state in Mexico; producing
96,557 MT of shrimp in 2008, representing 49.2%
of the national catch. Although the majority of
shrimp produced in Mexico (66.3% of national
shrimp production) now comes from aquaculture,
trawling still represents a sizable economic force
and has significant environmental and
socioeconomic impacts. According to world
averages compiled by the FAO, global shrimp trawling has an average rate of 84% by-catch, the highest
by-catch percentage of any fishing industry, and produces one third of global fisheries discards. By-catch
rates in the southern GOC have been documented between 83% and 97%, exemplifying that the percent
of by-catch from the trawled shrimp fishery in the GOC is generally higher than the global average. The
overcapitalization of the shrimp trawling fleet also causes economic impacts on small-scale fisheries,
resulting from competition for the same resources, habitat disturbance, and the by-catch and discard of
juveniles of important commercial species, as well as the retention and sale of marketable-sized
individuals of commercial species. Information specifically about the by-catch associated with trawling in
the GOC is needed to inform the development of sustainable fisheries management programs.
Beginning in 1999 Prescott College students have participated in on-board shrimp trawler studies in the
Kino Bay region. The study began as an educational
experience for students in the Marine Conservation Biology
classes. Over time we began to frame research questions
relative to the economic development of the fishery and the
economic and ecological impacts of by-catch mortality
resulting from the fishery. In 2005 we published an article
entitled “Export market influence on the development of
the Pacific shrimp fishery of Sonora, Mexico”. Since 2003 we
have sampled by-catch from 95 trawl sets on 11 boats over
23 nights, during, at minimum, the month of November of
2003, 2004, 2006, 2007, 2008, 2009, 2011, 2012, 2013, and
2014. As of 2014, a total of 221 species, including 130
species of fish from 58 families, 90 species of invertebrates
from 14 phyla, and one sea turtle species have been
documented throughout this study, and a 87.72 % rate of
by-catch was calculated based on data from the all years
combined. This study highlights the strong ecological and
economic rationale for by-catch management within the
shrimp fishery of the GOC.
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PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
Throughout the by-catch monitoring project, the presence of sensitive by-catch species has been
observed. These species include the Pacific Seahorse (Hippocampus ingens), Totoaba (Totoaba
macdonaldi), Loggerhead Turtle (Caretta caretta), Pacific Angel Shark (Squatina californica), Scalloped
Hammerhead (Sphyrna lewini), Shovelnose Guitarfish (Rhinobatos productus), Oscillated Electric Ray
(Diplobatis ommata), and Golden Cownose Ray (Rhinoptera steindachneri), all of which are listed on the
IUCN Red List under varying degrees of severity from Critically Endangered to Near Threatened.
Additionally there are several species common in the by-catch, which have commercial importance to
the local panga fishers of Kino, whose populations in the GOC have rarely, if ever, been studied. These
include the Bullseye Pufferfish (Sphoeroides annulatus), and the Finescale Triggerfish (Balistes polylepis),
and nearly all of the 23 species of elasmobranchs documented throughout the by-catch monitoring
project. Elasmobranchs are known to be particularly vulnerable to large-scale extraction, and it is also
known that at least two elasmobranch species present in the by-catch have genetically distinct
populations in the Gulf (the Shovelnose Guitarfish and the Pacific Angel Shark). Participants of the bycatch monitoring project have noted a marked increase in the retention of sensitive and commercially
valuable species onboard the trawlers, as the practice of selling by-catch to local panga fishers has
become more prevalent. This portion of the study aims to record the frequency of these species caught
as by-catch as well as collect information about the size and maturity of every individual.
2008-2009 season report: We analyzed all of our by-catch data and summarized the results.
Results from this study were used to submit comments to Mexican National Fisheries Institute
(INAPESCA) for use in the revisions of the “Carta Nacional Pesquera”. We noted that several of the
species frequently found as juveniles in the by-catch are both highly valued by commercial small-scale
fishers in the region, and are also particularly sensitive to overexploitation due to their life histories.
2009-2010 season report: This year we revised the data collection protocols and added new
research questions and methodologies to further study the impact of trawling on certain sensitive
and/or commercially important by-catch species. Data from this year’s sampling indicated a by-catch
rate of 86.5% by weight. As of this year a total of 181 species, including 114 species of fish from 55
families, 66 species of invertebrates from eight phyla, and one sea turtle species have been documented
throughout the six years of this study. Over the course of the study, photographs have been taken of
every species and compiled into a Power Point Catalog to be used for training and onboard reference by
observer teams. In 2009, regional taxonomy experts reviewed the cumulative photo catalogue to ensure
correct species identification.
The results of this study were presented at this year’s XII Congreso de la Asociación del Mar de
Cortés y VI Simposium Internacional Sobre el Mar de Cortés in Guaymas, Sonora, where we networked
with academics and professionals in the fields of fisheries, population genetics, and elasmobranchs,
encouraging outside researchers to come and assist with the project. In addition, these data will be used
in an article to be submitted for publication.
This year we added additional methodologies to collect data on the species of special concern. To
quantify the incidence of juvenile, sensitive, and/or commercially important by-catch species, all
individual elasmobranchs (excluding the Urobatids, which were far to numerous for the scope of this
study and do not have commercial value), Finescale Triggerfish, Bullseye Pufferfish, and Pacific
Seahorses that were present in the by-catch were measured, weighed and sexed (when possible) to
obtain a measure of the landed biomass and size-frequency data. These particular species were chosen
because of their consistent presence in the by-catch, the feasibility of collecting all individuals, and the
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PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
general lack of available data on regional populations. Other common and commercially important
species, such as the Urobatids, flatfish, corvinas, and Blue-swimming Crabs (Calinectes spp.) were too
numerous for the scale of this study. Data were collected from18 trawls on one trawler over four nights
in November of 2009. Through literature reviews, we were able to determine that 99% of Finescale
Triggerfish, 95% of Bullseye Pufferfish, and 80% of male and 78% of female Shovelnose Guitarfish
recorded in our study were below the minimum known reproductive size.
2010-2011 Season Report: Due to the inability to receive permission from the Kino port captain
to board trawlers in the region, field data for by-catch project was not collected this year. We have now
begun to seek official collaboration and permitting for the project through Regional Fisheries Research
Center of Guaymas (CRIP–Guaymas) and Mexican National Commission of Aquaculture and Fisheries
(CONAPESCA). An article entitled “Management Implications of the Biodiversity and Socio-economic
Impacts of Shrimp Trawler By-catch in Bahía de Kino, Sonora, México” was completed and submitted for
publication to a peer-reviewed journal.
2011-2012 season report: This season we were able to monitor by-catch associated with seven
trawls over two nights. Size, sex and sexual maturity data were collected for all species of
elasmobranchs. Our work on this project through 2010 were published in a peer-reviewed on-line
journal.
Meltzer, L., Blinick, N.S. and A. B. Fleishman. 2012. Management Implications of the Biodiversity and
Socio- Economic Impacts of Shrimp Trawler By-Catch in Bahía de Kino, Sonora, México. PLoS ONE 7(6):
e35609. doi:10.1371/journal.pone.0035609
2012-2013 season report: This season we were able to monitor by-catch associated with eight
trawls over two nights. Size, sex and sexual maturity data were collected for all species of
elasmobranchs. Conversations with officials from CRIP-Guaymas about future directions and
management implications of the project were initiated.
2013-2014 Season Report: This season we were able to monitor by-catch associated with 23
trawls over five nights in October and November and found an average of 88.84% by-catch. There were
11 previously unobserved species recorded including two elasmobranchs, the Pacific Sharpnose Shark
(Rhizoprionodon longurio) and the Oscillated Electric Ray (Diplobatis ommata) which is listed as
Vulnerable (IUCN). A pilot study was initiated to determine the current economic value of Paralichthys
species which was found to total 5,550 pesos in present-day market value. Results were presented as a
scientific poster entitled, “Ecological and Socio-economic impacts of by-catch mortality associated with
shrimp trawling in Bahía de Kino, Sonora, México” at the Western Division of the American Fisheries
Society conference. Additionally, a Café Comunitario was held in both Punta Chueca and Desemboque
to share the project’s goals and results, and to open the door for future collaboration with interested
community members.
2014-2015 season report: This season we were able to monitor bycatch associated with 25
trawls over six nights in October, November, and December of 2014, and February 2015.The calculated
percentage of bycatch per trawl ranged from 74.01% to 98.43% with a season average of 89.36%; this
rate rose throughout the season. The number of species recorded per trawl ranged from 53 to 73. In
total, 174 species were recorded throughout the season including the following 25 previously
unrecorded species (7 fishes and 18 invertebrates) (Table 20).
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PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
Table 1. Species recorded in shrimp trawler by-catch during 2014-2015 season. Blue indicates fish.
Green indicates invertebrates .
Scientific Name
Common Name
Date(s) Recorded
Rhinobatos glaucostigma
Speckled Guitarfish
Oct. 14, 2014
Cephaloscyllium ventriosum
Swellshark
Feb. 6, 2015
Raja velezi
Rasptail Skate
Feb. 6, 2015
Brotula clarkae
Pacific Bearded Brotula
Feb. 6, 2015
Caranx vinctus
Cocinero
Cheilotrema saturnum
Black Croaker
Lobotes pacificus
Pacific Tripletail
Nov. 12, 2014
Demospongiae
Red Sponge
Dec. 10, 2014
Unknown
Unknown Anemone
Feb. 6, 2015
Unknown
Unknown Annelid Worm
Feb. 6, 2015
Arca pacifica
Pacific Ark Shell
Chione amathusia or californiensis
Venus Clam
Dosina (?)
Unknown Tan Bivalve A
Anadara sp.
Cockle Shell
Unknown
Unknown Small Blue
Unknown
Slipper Snail
Oliva porphyria
Tent Olive Snail
Feb. 6, 2015
Oliva polpasta
Bulbous Olive Snail
Feb. 6, 2015
Strombus gracilior
Pacific Fighting Conch
ALL
Unknown
Unknown Gastropod
Nov. 12, 2014
Unknown
Unknown Crab
Ethusa ciliatifrons
Giant Ciliate Ethusa
Dec. 10, 2014; Feb. 6, 2015
Parapinnixa sp.
Unknown Pea Crab
Nov. 12, 2014
Pilumnus sp.
Unknown Pilumnus Crab
Nov. 12, 2014
Unknown
Sea Cucumber Sp. C
Nov. 19, 2014
Feb. 6, 2015
Nov. 12, 2015
Oct. 15 – Nov. 9, 2014
Nov. 9, 2014
Nov. 9/12, 2015
Nov. 9, 2014
Nov. 19, Dec. 10, 2014
Feb. 6, 2015
Nov. 9, 2014; Feb. 6, 2015
To further the study objective of collecting data on species of special concern, a new protocol for
determining maturity in female elasmobranchs through dissection was implemented on a trial basis. In
the past, we have assigned maturity to elasmobranchs by measuring total length in sharks or disc width
in skates, then comparing those to published sizes at maturity for each species. Unfortunately,
elasmobranchs are understudied in the GOC, meaning that for many species the maturity information is
missing, or only exists from studies done in the Pacific Ocean. For these reasons, one of the added
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PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
objectives to this study was to clarify the maturity of individuals ourselves instead of relying on
published sizes at maturity. For males, maturity was determined onboard through an assessment of the
claspers. Individuals with fully calcified claspers that rotated 180 degrees and tips that opened easily
when flexed were considered mature. Females were brought back to the station, frozen, and later
dissected. Measurements included follicle diameter, shell gland width and weight, and ovary weight,
with each measurement taken from both sides. These measurements were compared to published
numbers when available and to the measurements of gravid individuals if there were no publications.
We documented a previously unrecorded species into the Kino Bay- two individuals of the Speckled
Guitarfish, Rhinobatos glaucostigma, were recorded in our study on October 14, which turned out to be
the Northern-most record for this species in the GOC.
Due to the extended field season, one of the most interesting things we were able to observe was how
the species composition changes from October to February. This was an uncharacteristically warm year,
resulting in the typical colder-water indicator species that we usually see in November, be recorded in
February. These species include Paralichthys spp., Mustelid spp., Raja spp., and Sicyonia disedwardsi.
We observed many individuals from several species over the season that were emaciated, melanistic,
and potentially diseased. This could be a new phenomenon based on poor conditions and indicative of
an unhealthy bay, or may have been overlooked previously in the study. These species include
Sphoeroides annulatus (most individuals were significantly thin with small round lesions on their skin
that resulted in the fishermen not retaining them for food on October 14), Orthoprisis reddingi (three
individuals on two nights found to be melanistic and emaciated; comments from the crew indicate they
had never seen them like this before), Cheilotrema saturnum (one individual-- newly recorded specieswith a very unusual body depth index).
This was the first year we have observed the deaths of California Sea Lions in association with the
shrimp fishery- they get caught in the propeller when there are large groups of them surrounding the
boat. We are seeing decreased numbers of some species of special concern such as a complete three
year absence of Hippocampus ingens which has previously been recorded every year from 2003-2011.
An educational workshop was given in October 2014 to interested members of the Comcaac community
and Prescott staff about the project's methodology and results. On January 28, a presentation was given
to an audience of about 60 people at Club Deportivo, a sports fishing club in Kino Bay that focused on
the project's results and consumer awareness.
We began contributing data, specimens, and photographs to several international scientific databases,
including the website Mexfish, the Marine Vertebrate Collection at SCRIPPS, and the Smithsonian
Tropical Research Institute's Shorefishes of the Tropical Eastern Pacific online information system. We
had the opportunity to participate in an informal fish-identification lab and discussion about the project
at SCRIPPS to improve our identification techniques, broaden our collaborative network, and contribute
unusual specimens to the collection. As of now, we have contributed photographs of 24 different fish
species to Mexfish (www.mexfish.com) from the Kino Bay region and plan on continuing this effort in
following years.
The data from this study is being used in a project entitled '6&6'; a collaborative endeavor with Next
Generation Sonoran Desert Researchers to artistically communicate scientific projects in the region. This
project will be underway for at least the following year, and will likely result in a travelling exhibition
through the United States and Mexico.
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PRESCOTT COLLEGE KINO BAY CENTER FOR CULTURAL AND ECOLOGICAL STUDIES
SHRIMP TRAWLER BY-CATCH DIVERSITY AND IMPACT STUDIES , 2008-2015
What we had previously identified as Bascanichthys cylindricus has been corrected to be Bascanichtys
bascanoides based on our preserved specimen. Our data means a range extension as well as a maximum
known length for this species. The unidentified Sea Catfish has been identified as Bagre panamensis; this
may be two separate species. The unidentified Bonefish has been identified as Cortez Bonefish, Albula
gilberti. What we had previously identified to be Cynoscion xanthulus, was corrected to be Cynoscion
reticulates; we need to watch this group carefully to see if we do in fact see both species.
2015-2016 proposal: We plan to increase bycatch monitoring effort and would like to collaborate
with regional elasmobranch experts to be able to analyze population impacts resulting from bycatch
mortality. We also intend to continue consumer and public education about the impacts of shrimp
trawling on ocean ecosystems and populations and upon small-scale fishing economies.
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