Download Genetic considerations in shellfish restoration

ICSR 2005 forum and discussion
Plenary speakers were invited to discuss within short synthesis the main information
presented during the session they have been invited for. These synthesis by the plenary
speakers are expected to provide some help to decision makers in terms of environmental
policies. These synthesis state (when possible) on risk assessments (pathogen, pollution,
exotic species introduction, overfishing…), provide orientations for basic and applied
research, give some inputs regarding legal and policy issues at the international level, and
provide future direction to address these issues. Finally, these syntheses gave some inputs
on the integration of the environmental issues for the sustainability of shellfish resource
and the concerted management of coastal zone.
Sponsors: The ICSR 2005 was sponsored by Brest Métropole Océane (BMO), Centre
National de la Recherche Scientifique (CNRS), Conseil Général du Finistère, Florida
Gulf Coast University (FGCU), Institut français de recherche pour l’exploitation de la
mer (Ifremer), Institut Universitaire Européen de la Mer (IUEM), Organization of
Economic and Cooperative Development (OECD), Région Bretagne, South Carolina Sea
Grant Consortium, Université de Bretagne Occidentale (UBO), Ville de Brest and
Virginia Sea Grant Consortium.
Diclaimer: The opinion expressed and arguments employed in this publication are the
sole responsibility of the authors and do not necessarily reflect those of the OECD or of
the governments of its Member countries.
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Summary
Assessment of shellfish habitat and resources .................................................................... 3
Importance of hatcheries and aquaculture in shellfish restoration...................................... 6
Genetic considerations in shellfish restoration ................................................................... 8
Pathology and epidemic considerations in shellfish restoration ...... Error! Bookmark not
defined.
Shellfish fitness consideration in shellfish restoration...................................................... 12
Exotics/Invasive/Introduced Species Considerations ....................................................... 16
Shellfish-Ecosystem linkages ........................................................................................... 19
Environmental quality monitoring and improvements ..................................................... 21
Historical considerations in shellfish management........................................................... 23
Socio-economic, policy, outreach and education aspects of shellfish/habitat restoration 28
Integrated and concerted approaches of shellfish restoration and enhancement .............. 32
Fisheries and aquaculture management ............................................................................ 33
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ASSESSMENT OF SHELLFISH HABITAT AND RESOURCES
L.D. Coen1 and C.L.J Frid2
1
Marine Resources Research Institute, SCDNR, Charleston, SC 29412 USA. E-mail:
[email protected]
2
School of Biological Science, University of Liverpool, Crown Street, Liverpool L69
7ZB, UK. E-mail: [email protected]
The diverse Shellfish Habitat and Resources Session included two invited plenary
presentations, 13 offered oral papers and 8 poster presentations. Individual presentations
ranged from: (1) deep-water offshore to coastal near-shore or inshore systems; (2)
latitudinally from temperate to subtropical waters; (3) restoration efforts and their
evaluation (goals, metrics, success criteria, stats); (4) short- and long-term monitoring
datasets (both fisheries and ecological functions); (5) native to introduced (non-native)
species; (6) diversions of freshwater and their impacts on shellfish populations and
related restoration; (7) potential aquaculture impacts; and (8) fishing gear impacts and
associated efficiencies.
Some highlights included improved ways to assess the impacts of fishing gear (trawlers
and dredgers) on benthos (e.g., invertebrates, maerl beds) and target species. As with
many previous studies, the intensity and frequency that many areas are repeatedly
disturbed is amazing. The topic of freshwater diversions was highlighted in light of recent
projects and hurricanes in the Gulf of Mexico. The plenary by Coen and related papers
provided a framework for viewing oyster habitats as critical systems with invaluable
associated ecosystems ‘services’ worth protecting, enhancing and restoring at a cost
above and beyond their resource values. He also identified potential restoration goals and
discussed and ranked current approaches, sampling/monitoring methods, and associated
metrics for these habitats. The value of reference sites for monitoring was also stressed,
along with current efforts by a group of active oyster restoration practitioners to develop
BMPs. The second plenary by Frid reviewed the impacts of fishing gear on biological
diversity in EU waters and posited how these fishery disturbances might be better
managed to protect these diverse and impacted marine habitats while including
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stakeholders in the decision making process. There were also several papers assessing
that status and trends of fished molluscan species (e.g., the IFREMER/REMORA
network), especially what is a sustainable level of harvesting pressure. Novel approaches
such as remote sensing were also discussed, as were improved methods for assessing
dredge efficiencies with respect to scallop fisheries in Canada. The subject of
interactions among extensive C. gigas, mussel and native oyster aquaculture operations,
non-natives, and potential habitat alterations was discussed in this and several other
sessions. One that stood out and is symptomatic of what is occurring in many areas
worldwide was the impact of C. gigas from nearby aquaculture farms on a unique
biogenic habitat, sabellariid worm reefs.
It was therefore possible to draw some emergent lessons from the session. From the
material presented it is clear that the field of shellfish habitat investigations is healthy
with high quality science addressing issues of both a fundamental and applied nature.
Such studies include consideration of the factors influencing the growth and ecology of
shellfish resources in different environments, the use of shellfish restoration schemes as
model, replicated, experimental systems to shed light on the ecology of the associated
fauna and in the development of tools for monitoring natural and restored shellfish
resources. It was also clear that much of the fundamental science done in recent years
and new initiatives were contributing to the development of more inclusive and holistic
environmental schemes. In particular this was seen through the recognition of the
functional role of shellfish in ecosystem dynamics and the need to ensure that functional
as well as species biological diversity are protected. Aquaculture and fishing gear
impacts are becoming ever more apparent and are symptomatic world-wide, not just in a
few discrete localities. Like tropical habitats such as coral reefs, biodiversity in
temperate waters is being impacted significantly.
The most striking feature of the presentations/posters, however, was the apparent
difference in approach between U.S. efforts and other nations in their response to threats
to shellfish resources. For example, the studies emerging form the U.S. focussed on
physical restoration (i.e. function and structure) of the system, while in most other studies
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the emphasis was on identifying of, and subsequent management of the threats, allowing
‘nature’ to restore the system. However, reflection on this dichotomy reveals it probably
has its basis in the nature and extent of the ecosystems involved. This needs to be
investigated further.
This may be explained in large part by differences in these systems, with U.S.
shellfisheries often associated with large embayments, complex estuaries and surrounding
wetlands or watersheds, whereas the other countries often involve small, dynamic
estuaries or open coast shellfisheries. Alternatively, it may simply be a result of those
scientists represented at the ICSR versus those at an Estuarine Research Federation or
European Society of Limnology and Oceanography meeting?
In continental American shellfisheries are often associated with large embayments,
complex estuaries and wetlands. In these systems it is feasible to build structures and
actively restore the system. In fact given the nature of the hydrography of such systems
natural reseeding may not ever occur. In contrast, the small dynamic estuaries of Europe
and the open coast shellfisheries are areas where extensive, heavy engineering would be
required to overcome the dynamic, tide and storm, forces operating and these systems
tend to have remnant shellfish populations that can act as seed sources such that recovery
can occur by natural processes. Thus the contrast is not cultural or geo-political but
rather a reflection of the underlying ecosystem dynamics. Ultimately we can re-establish
native shellfisheries and their ecosystem functions through a combination of active
intervention (i.e. restoration) and by promoting natural processes that can re-establish
them (i.e. recovery). Fine-tuning fishing pressure the key, along with adaptive
management approaches.
Several obvious potential workshop themes emerged from the oral and poster sessions,
including: (1) how might global climate change affect molluscan species? (2) is global
change and novel exotic species affecting important molluscan habitat-engineers and
related species? (3) do introduced (non-native) species create valuable habitats or change
other unintended habitats in an unpredictable way? (4) are the different perceptions of
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shellfish habitats and related restoration approaches taken in U.S. simply do to system
differences or something more intrinsic? (5) what are the different ecological services
provided by fished, unfished and aquaculture populations? (6) for protection of essential
fish habitats or ‘EFH’, is structure or function the most important characteristic(s)? and
(7) can we view cascading ecosystem effects due to declines or additions of filter-feeding
molluscs in a broader context? These are a few of the potential directions sessions at
future ICSR meetings or workshops might take.
IMPORTANCE OF HATCHERIES AND AQUACULTURE IN
SHELLFISH RESTORATION
R. Roberts
Cawthron Institute, Private Bag 2, Nelson, New Zealand.
E-mail: [email protected]
Hatcheries have an important part to play in shellfish restoration. For many species, there
is no suitable wild source of juveniles to catch for redeployment, so hatchery production
is the only option for supplementation. Furthermore, wild catch may be counterproductive if it removes animals that would otherwise have recruited naturally.
Hatcheries can also undertake selective breeding programmes for conservation or
commercial ends. For example, disease tolerant lines can be developed for shellfish
restoration. Hatchery production coupled with modern genetic techniques allows control
of the genetic composition of juveniles, which may be critical in restoring populations
that have been reduced to low numbers.
The technology for hatchery production of a “new species” will develop progressively
over time. The first step is to prove that hatchery production is possible, so that hatchery
produced juveniles can be considered as an option for restoration. This may also provide
modest numbers of juveniles for preliminary experiments.
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Further development is then required to achieve hatchery production that is reliable, costeffective and meets the scale required for the intended restoration effort. Much of the
current hatchery research focuses on this phase of development. This was reflected in the
mix of papers presented at the ICSR 2005, which addressed topics such as probiotics for
larval rearing, optimization of algal diets, continuous-flow larval rearing systems, disease
control agents and hatchery scale-up.
Once hatchery juveniles are being used for restoration, hatcheries will face several
significant regulatory issues. They will be responsible for ensuring that juveniles are free
of pests and diseases that could be transferred to the release site. They may also be
required to meet genetic criteria if these are set out in future regulations. Key goals will
include the maintenance of the genetic structure and genetic diversity of wild
populations. Defining appropriate targets for these goals is the subject of current debate.
For example, at what temporal and spatial scale should population structure be defined?
Should we be using genetic markers with ever-higher resolution to define population
structure, or do we begin to resolve structure that lacks functional or evolutionary
significance? What are the effective population sizes for wild shellfish? A more detailed
account of genetic issues is given in Patrick Gaffney’s summary of the genetics session.
The high fecundity of shellfish means that millions of juveniles can be produced from
just a few parents. Futhermore, genetic differences in fertilization success and the
performance of larvae and post-larvae may mean that many spawners may not contribute
juveniles derived from “mass spawnings”. To counter such issues, hatcheries may be
required to produce spat via single pair crosses. This increases the cost and the technical
challenge for the hatchery, but will be aided by recent developments in larval rearing for
single pair crosses.
The interplay between hatchery operations and genetic issues is a key issue for policy
development. An informed and balanced approach to the genetic considerations is
necessary to allow progress to be made within practical and affordable limits. There
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needs to be further research on key genetic issues, and dialog between regulators and
hatchery operators, to ensure that regulation is realistic and not just idealistic. Further
research is also needed to improve the reliability of hatchery production. In the absence
of perfect knowledge regulators will continue to weigh the risks of proceeding with a
shellfish restoration project against the benefit of the project.
GENETIC CONSIDERATIONS IN SHELLFISH RESTORATION
P. Gaffney
Marine Biology-Biochemistry Program, College of Marine Studies, University of
Delaware, 700 Pilottown Rd, Lewes, DE 19958, USA. E-mail: [email protected]
The primary genetic concerns in shellfish restoration are the genetic effects on the
resident (target) population. To determine whether such effects will be modest or
substantial, harmful or benign, we need information on both the target population and the
restoration (hatchery) stock. For a given species, the basic taxonomy and its geographic
distribution must be settled, and genetic methods for identification are desirable. For
many Crassostrea species, basic taxonomy is only now being established. If a species is
geographically subdivided into genetically distinct subpopulations, do we know where
the populations (and boundaries) are? Genetic techniques can be used to identify species
and regional populations, providing information essential for agencies regulating
international and domestic transport of shellfish for restoration purposes as well as trade
and aquaculture.
Regarding the target population, it is important to know the geographic distribution of
genetic diversity. This information is useful for broodstock selection and breeding
programs in most situations, and will enable restoration programs to avoid planting seed
that are poorly suited to the target habitat. The extensive human-mediated transport of
oysters will often have blurred historical biogeographical structure. Genetic tools will be
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useful for locating undisturbed ‘relic’ populations deserving special protection, if they are
to be found.
Equally important is the stock used for restoration. Is it genetically improved for traits of
interest (growth, disease resistance, etc.) under natural grow-out conditions? Is it inferior
to wild stock in any performance traits? Does it have adequate genetic diversity? Whether
a genetically improved stock should be used for restoration will depend on the condition
of the natural (target) population, and whether it appears likely to benefit from the
infusion of new genotypes. Correct spawning protocols and genetic pedigree monitoring
should be used in propagation of hatchery stocks to maintain adequate genetic diversity
and prevent inbreeding.
The use of hatchery stocks for restoration offers the positive prospect of improving
genetically degraded natural populations (i.e., countering negative selection caused by
overfishing). In addition to the immediate increase in numbers resulting from large-scale
plantings, the native population may be improved by long-term introgression of favorable
alleles from the restoration stock. Application of the Ryman-Laikre model indicates that
the possible negative effects originally described for salmonids with extremely low
effective population sizes are unlikely for most shellfish populations.
Because shellfish restoration programs are expensive, it is essential to determine whether
outplanted seed are surviving and reproducing. Genetic tools provide effective means of
evaluating the success of planted stocks. Because even degraded natural populations may
contain millions of individuals, considerable dilution of planted stocks will occur,
requiring large sample numbers to estimate the effective contribution accurately. Various
high-throughput genetic methods are currently available for this purpose.
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PATHOLOGY AND EPIDEMIC CONSIDERATIONS IN
SHELLFISH RESTORATION
S. C. Culloty1 and F.-L. E. Chu2
1
Department of Zoology, Ecology and Plant Science, Aquaculture and Fisheries
Development Centre, University College Cork, Lee Maltings, Prospect Row, Cork,
Ireland. Email: [email protected]
2
. Department of Environmental and Aquatic Health, Virginia Institute of Marine
Science, College of William and Mary, Virginia, USA. Email: [email protected].
This session included twenty four presentations, two of which were plenary lectures. The
presentations encompassed a wide range of pathogens and their host species. The host
species included the economically important marine bivalves, Ostrea edulis, Crassostrea
virginica, C. gigas, C. ariakensis, Mercenaria mercenaria, Mytilus edulis Ruditapes
philippinarum, R. decussates, Venerupus aurea and Tapes pullastra. The pathogens
discussed were the parasitic protozoans, Bonamia ostreae, Marteilia refringens,
Perkinsus marinus, Haplosporidium nelsoni, the bacteria, Vibrio tapetis, Vibrio spp.,
Rickettsia like organisms and trematodes such as Himasthla quissetensis.
The papers covered a range of subjects including pathogen life cycles, disease
transmission, host-parasite interactions and environmental effects, host defense and
pathogen virulence factors, disease monitoring, disease diagnostic techniques, disease
prevention and control. It appears that for some diseases and pathogens basic studies are
required to elucidate the biology of the pathogens and their hosts. For example,
uncertainties still exist in relation to the life cycle and mode of disease transmission of
certain pathogens such as B. ostreae and H. nelsoni. Knowledge of pathogen life cycles
and a better understanding of the biology of host and pathogen may lead to the
development of means for disease control and strategies for restoration. Several studies
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emphasized the importance of understanding the host parasite interaction and
environmental effects at the cellular and molecular levels e.g. in terms of host defense
mechanisms and parasite virulence factors as observed with the antioxidant activities in
P. marinus and in pathogenis Vibrios observed in summer mortalities in C. gigas .
Understanding the interaction and mechanisms that pathogens employ to evade host
defense may potentially provide a strategy for long-term management of diseases.
Significant progress is being made in some areas that will allow greater understanding of
this interaction e.g. with the sequencing of the P. marinus genome that is currently being
undertaken.
It was clear from a number of studies that programs of long term disease monitoring are
necessary to allow us to develop models and mechanisms for disease event prediction e.g.
in the monitoring of B. ostreae in oysters in Brittany over a twenty year period. This
allows long term monitoring of disease progression and the evolution of the host parasite
interactions. It was also stressed that long term data on mortality events is required to
develop a full picture of the effects of disease events and this needs to be emphasized to
all interested parties e.g. farmers, researchers etc.
Though diagnostic techniques have become more sophisticated in recent years with more
emphasis being placed on molecular based techniques it is clear that more progress needs
to be made on studies to look at the comparative sensitivity of these techniques and to
ensure that less expensive, less time consuming and more specific methodologies are
made available. More validation studies between laboratories and optimization of some
techniques are still required.
Control and treatment methods were also discussed with the potential use of
chemotherapeutants and probiotics as mechanisms for administering and reducing the
effect of pathogens respectively. However, before being utilized the human hazard and
environmental impact of these methods needs to be investigated. The emphasis in some
of the presentations involved a long-term strategy to reduce the effect of disease by
introducing selective breeding programs to develop resistance in infected stocks.
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SHELLFISH FITNESS CONSIDERATION IN SHELLFISH
RESTORATION
J.-F. Samain
Ifremer, PFOM/LPI, BP 70, 29280 Plouzané, France. E-mail: [email protected]
Introduction : fitness, different approaches :
Papers delivered during this session can be grouped according to different aspects where
fitness can be evaluated in different ways. Growth, reproduction and survival in different
environments are the main criteria reported for species cultivated in new sites. Fitness
performances are also investigated through different mechanisms of adaptation, resulting
from total phenotypic variance including a genotypic component and two environmental
components (a reversible one (flexibility) and an irreversible one (plasticity)) (Piersma
and Drent 2003). At last, multifactorial interactions during seasonal reproduction may
have detrimental impacts on adult components of fitness (i.e. reproductive value at age of
first maturity), as well as on fertilisation rate and survival to age at first maturity (Olive
2000).
Fitness in different environments: it was measured in the simplest way by growth and
survival, and was reported for different species as Crassostrea gigas, Ostrea edulis,
Mytilus galloprovincialis in different rearing sites. These sites can be from the same or
different productive areas and characterized by different environmental conditions as,
temperature, salinity, oxygen and trophic level, emersion time, position in the water
column or near by the sediment. Importance of environmental factors on bivalve
performances is well known as shown for C. gigas by King et al. in Wales (UK) and in
Bizert lagoon in Tunisia (S. Dridi), or for mussel M. galloprovincialis in Spain
(Galimany et al.). Sediment proximity appeared one of the negative environment factor
for growth and survival for C .gigas in France (Knoery et al.) or growth for the clam
Ruditapes decusatus in Basque Country (Bald et al.). Limits of adaptation can be attained
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for native species, when environmental variables are changing over usual extreme values
where organisms were acclimatized. This can be observed during exceptional climatic
events for a native species as the Brest scallop Pecten maximus mass mortality during a
very cold winter in 1962. This can be also the case after introduction of exogen species in
new environments. This justifies that a number of presentations dealt with this approach
and are yet reported over the world for different shellfish species. At last, a long term
climatic temperature shift, as currently observed, can lead usually adapted species to
critical conditions. i.e : C. gigas oyster summer mortality appeared recently in Normandy
(North France) because of an 1°C increase of the annual seawater mean temperature the
last 20 years, in areas where summer temperature us ually never attained a critical 19°C
before.
Adaptation mechanisms: these mechanisms were approached at different levels. One
concerns the storage of glycogen and lipids during the rest period. This is an important
factor controlling reproduction and fecundity, two criteria associated to fitness, insuring
success of reproduction the next year. This was reported by Kamara et al. for R.
decussatus in Morocco, or by a molecular approach of glucose transport for C. gigas
oyster (Hanquet-Dufour et al.). Different interactions between reproductive activity,
hemocyte parameters and infections were reported by Choi et al. for Ruditapes
philippinarum in Korea, Da Silva et al. for flat oyster Ostrea edulis in Galicia (Spain),
Mori and Takahashi in Japan and Samain et al. in France for C. gigas, suggesting
possible weakness of hemocyte activity and defence mechanisms with reproduction
intensity. This can be detrimental for gene transmission when mortality occur before the
first spawning as reported in Juvenile oyster desease (JOD) for C. virginica oyster (Ford
et al.) or for C. gigas summer mortality the first year.
Adaptation capacities depend on species and their evolution. For a single species,
complex interaction between genotype (polymorphism diversity) and environment
provides new fascinating results. Today, molecular biology and genomic tools allow the
study of genetic expression under environmental conditions. An increasing number of
papers were presented in this field. Molecular approaches of glucose transport and
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metabolism (Hanquet-Dufour on C. gigas) will provide information on key genes that
could be limiting steps for this major metabolic pathway. Thereafter, polymorphism of
identified “candidate genes” will be a necessary step to look for genotype-phenotype
relationships faced to different environmental conditions. This is a new way opened for
future researches with the aim to select different interesting genotypes in the same
species for the best adaptation to specific environmental conditions. In this field, amylase
gene polymorphism was reported to be associated to differences in growth performances
in C. gigas (Huvet et al.) possibly through differences in adaptation capacities to food
levels. Da Silva illustrated clearly this genotype diversity using different populations of
O. edulis flat oyster as broodstock. Resulting families planted in the same area had
different hemocyte characteristics and susceptibility to pathogen infections. Other
important genes involved in adaptation processes, as genes concerned by response to
environmental stress (Meistertzheim et al. Farcy et al, David et al.) were reported for C.
gigas oyster. Polymorphism studies on candidate genes are ongoing. At last, polyploid is
another alternative to study interaction between reproduction and defence as it was
reported by Duchemin et al.
Limits of fitness: The case of the C. gigas oyster summer mortality illustrated limits of
fitness in a multifactorial interaction between oyster, environment and opportunistic
pathogens (Mori et al. in Japan, Samain et al. in France). A very interesting similarity
appeared in environmental factors acting on this species in its native habitat (Japan) and
as an introduced species (France), suggesting some strong similar mechanisms. On one
hand, a lot of papers appeared on shellfish diseases all over the world this last two
decades involving emerging environmental problems in the species survival (Chesapeake
Bay and C. virginica oyster, R. philippinarum Manilla clam, C. gigas oyster...). On the
other hand, many presentations in other sessions reported on environmental changes
around the 70ies, under anthropic pressure. This suggests that aside pathologies, with one
known pathogen infecting a host whatever his physiological status and environmental
condition, appeared more complex multi causal pathologies, with different opportunistic
pathogens resulting from interactions between environment, host physiology (fitness
capacity) and pathogens.
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In conclusion: what about fitness and shellfish restoration
A very first step before restoration is preservation!
The C. gigas interaction model underlined possibilities to prevent mortalities by breaking
one among these necessary interactions. Restoration of environmental parameters to
acceptable values would be one possibility to prevent the problem. A trivial conclusion is
that preservation of marine ecosystems is one of the major ways to solve the restoration
problem!
Improving fitness by genetic selection seems possible:
Surprisingly, selection against such a multifactorial mechanism appeared possible with a
high heritability. This led the authors to suggest that a very limited number of genes
would confer this resistance. Many studies performed on such resistant and susceptible
lines, from classical physiological studies to genomic ones are going on with the hope to
provide information of the few genes involved in this phenomenon. This would
theoretically point out that it is possible to select against a detrimental environmental
pressure to prevent opportunistic pathologies, by increasing fitness, or by identification
and discard of the most susceptible genotypes. Probably, there is some future to improve,
by genetic selection, resistance of oyster faced to environmental changes. However,
limits of such possibility are probably depending on environment degradation status.
Again, preservation of actual situation is the necessary minimum.
New ideas:
One interesting question is to know if such interactions can also explain other pathologies
for other species in aquaculture, opening solutions to manage such events in the field. A
first question on possible similar interactions between reproduction/stress /and immunity
in different bivalves stimulated immediately discussion.
For the future, scientists from the main oyster producing countries propose (1) to
compare situations of summer mortality over the world, to optimize knowledge, confirm
and complete the proposed interaction model for different areas in the world and make
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appropriate recommendations for oyster industry sustainability; (2) to discuss about
possibilities to enlarge this model to other oyster or bivalve species; (3)to stimulate a
network to better explore links between genetic diversity and phenotypic responses (as
resistance to summer mortalities).
References :
P.J.W. Olive, C.Lewis and V. Beardall, 2000. Fitness components of seasonal
reproduction: an analysis using Nereis virens as a life history model Oceanologica Acta
23, 4, 377-389.
T.Piersma and J.Drent, 2003. Phenotypic flexibility and the evolution of organismal
design. TRENDS in ecology and evolution, 18, 5, 228-233.
EXOTICS/INVASIVE/INTRODUCED SPECIES CONSIDERATIONS
M. W. Luckenbach
Eastern Shore Laboratory, VA Institute of Marine Science, College of William and Mary,
P.O. Box 350 Wachapreague, VA 23480 USA E-mail: [email protected]
Presentations in this session examined a diverse array of topics including the effects of
introduced mollusks on native species, introduced shellfish pathogens, shellfish as
vectors for introductions and harmful algal blooms both as limiting factors in shellfish
restoration and as consequences of relocations of shellfish. The session began with an
overview of the current consideration being given to the intentional introduction of an
exotic oyster species, Crassostrea ariakensis, to the Atlantic coast of the U.S.,
summarizing the current state of knowledge about this species and asking what role
science was likely to play in the decision process. Several other presentations in the
session examined some of the consequences of previous shellfish introductions. Batista
and colleagues examined interactions between two oyster species, Crassostrea angulata
and Crassostrea gigas, that were introduced to the coast of France approximately one
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century apart to determine if the rapid expansion of C. gigas threatened remaining
populations of the congener. The expansion of C. gigas, over 30 years after its
introduction to the southern coast of France, to northern France, southern England and
the Wadden Sea was noted by Hily and colleagues, who discussed some of the positive
and negative consequences arising from the spread of this non-native species.
Competition between a native Mediterranean bivalve, Pinna nobilis, and an invasive
Indo-Pacific oyster, Pincata radiate, was examined by Soufi-Kechaou and co-workers.
Despite a lack of evidence for trophic competition, the distribution of the two species
suggests that competition is occurring and that populations of P. nobilis in some areas
are threatened by the invasive. The limpet Crepidula fornicate was introduced from
North America to the United Kingdom in the 19th Century and has now spread
throughout the Atlantic coast of Europe from Norway to Spain, where it has resulted in a
variety of documented impacts to native species and shellfisheries. Richard and
colleagues reported on variations in growth and fecundity of this species in relation
environmental factors and concluded that a high degree of phenotypic plasticity in this
species has contributed to its success in invading a broad range of habitats.
Nearly 50 years after the introduction of the non-indigenous pathogen Haplosporidium
nelsoni, which resulted in widespread mortality of the native oyster Crassostrea virginica
in the mid-Atlantic region of the U.S., Ford reported on the development of resistance
through natural selection in oysters in Delaware Bay. This development of resistance has
important consequences for efforts to restore populations of the native oyster to more
historic levels.
Two presentations in the session examined interactions between harmful algal blooms
and shellfish restoration efforts. Hégaret and co-workers investigated the possibility that
the translocation of shellfish as part of restoration efforts could be responsible for
transporting harmful algae species from one location to another. Their results reveal that
viable cells from harmful algae pass through the guts of oysters, clams, mussels and
scallops, and thus movements of these shellfish could serve to transport harmful algae
species between locations. Wikfors and colleagues noted that presence of two toxin
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producing algal species, Prorocentrum minimum and Karlodinium micrum, in estuaries
along the U.S. mid-Atlantic coast could limit efforts to restore native oysters. They noted
that considerable variation exists in the levels of toxin production by these species; they
are currently investigating environmental factors that affect this variation in toxicity with
the goal of helping to guide oyster restoration efforts in these estuaries.
The presentations in this session revealed a wide range in the use of the term restoration.
In some cases, such as the previous introductions to Europe and the current consideration
of introducing a non-indigenous oyster species to the U.S. Atlantic coast, the introduction
of exotic species were viewed, at least in part, as restoration. While in other instances,
restoration meant trying to recover from, reduce or mitigate for the effects of exotic
shellfish introductions. Often it was the response of native species to the introduction of
an exotic or invasive species that was the focus of restoration—for instance, the response
of a native bivalve in Tunisia to an invasive oyster, the effects of slipper limpets on
shellfish in Europe, or the impacts of protozoan pathogens or toxic algae on oysters in the
U.S. The important point here is that restoration may mean different things to different
people and different things at different times. Restoration of the French oyster industry
was achieved through the introduction of C. gigas over 30 years ago, but now restoration
is being invoked to mean protection of other species or habitats from C. gigas expansion.
The clearest re-occurring theme throughout this session was that ecosystems and their
associated species continue to exhibit change for many decades after the introduction,
intentional or otherwise, of exotic species. C. viginica continues to evolve resistance to a
pathogen that was introduced nearly 50 years ago. Nearly 35 years after its introduction
to France, C. gigas continues to expand its range into regions previously thought too cold
to support reproduction. Over a century after the opening of the Suez Canal, an invasive
bivalve from the Red Sea may be out-competing a native bivalve in the Mediterranean
Sea. The slipper limpet, Crepidula fornicate, aided by phenotypic plasticity in different
environments continues to expand its range and its impacts in Europe over a century after
its introduction. The presentations in this session provide examples of how the
introduction or invasion of a new species can have consequences that may take many
18
decades to ripple through the ecosystem. Future considerations of species introductions
in the name of restoration would be well advised to heed the lessons from some of the
examples presented in this session.
SHELLFISH-ECOSYSTEM LINKAGES
A.C. Smaal
IVO-CSO, P.O.Box 77, 4400 AB Yerseke, NL; E-mail: [email protected]
Shellfish communities are an important aspect of estuarine and coastal ecosystems. Their
aggregations have high densities. Epibenthic species like oysters and mussels form bed
structures, frequently categorized as keystone components or ecosystem engineers. Their
characteristic habitats play dominant structural and functional roles in the ecosystem. Due
to their sedentary life and high filtration activity shellfish beds create a large flux of
suspended particles towards the sediment, and by the formation and mineralization of
biodeposits there is a flux of dissolved inorganic nutrients into the water column, that
enhances phytoplankton growth. These feedbacks result in promotion of productivity and
stabilization of the ecosystem. Understanding and quantification of the feedback
processes require ecosystem-shellfish models.
Shellfish production for human consumption occurs in many areas by extensive culture,
i.e. on the basis of natural availability of resources as food and spat. Shellfish culture is
part of ecosystem processes and the feedbacks through the filter feeders play an
important role in the farming practice. Therefore ecosystem-shellfish models have in
many cases been developed in the framework of exploitation studies
Recent developments have been reported during the theme session (Fig. 1). Ecosystem
modeling now includes the role of zooplankton and carrying capacity models are
available that have a high spatial resolution due to detailed profiling of forcing function
data and improved hydrodynamic modeling. Habitat descriptions by using Geographic
Information Systems also have a high resolution. Relationships between shellfish
19
communities and their habitat are used for Habitat Suitability Indices. Impact models
now address effects on local benthic communities of longline cultures. At the population
level shellfish models include population growth by the input of seed, size specific
natural mortality and harvesting. The application of the Dynamic Energy Budget model
concept as a generic approach was demonstrated for eco-physiological shellfish
modeling. The model was validated for a range of estuarine systems. At the molecular
level the use of biomarker techniques was demonstrated to identify food resources of
different shellfish populations.
The studies presented are not only relevant for understanding the shellfish-ecosystem
linkages. As shellfish populations are used for exploitation but also for monitoring,
remediation and restoration, there is considerable interest in management of shellfish
stocks. Also exotic invasions of shellfish are an important topic. For management it is a
prerequisite to understand the relation between shellfish and the ecosystem, as shellfish
has many linkages with the ecosystem. Management of exploitation and restoration can
profit from new developments in shellfish-ecosystem knowledge as presented in the
theme session.
Conclusions
Shellfish - ecosystem linkage studies are required for understanding effects of
exploitation, restoration and introductions. Further development in this field will build
upon dynamic and habitat modeling that has made quite some progress over recent years.
Actual focus in many studies is on the coupling of dynamic and descriptive models at
different scales, focusing on carrying capacity at both farm and bay scale, and on the
impact on habitats.
Recruitment dynamics of shellfish populations is a complex process that has considerable
knowledge gaps. The role of food quality for larvae, predation on early life stages and
competition with zooplankton are topics that need to be addressed.
Composition and quality of phytoplankton assemblages as food for shellfish also in
relation to biotoxins is an issue that requires more knowledge.
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Knowledge of shellfish – ecosystem linkages is required for management that aims for
sustainable exploitation. Shellfish farming as well as shellfish restoration contributes to
the quality of the ecosystem. Sustainable shellfish farming is a tool in ecosystem
management, that can be optimized by proper knowledge of shellfish – ecosystem
linkages.
Shellfish – ecosystem linkages
Shellfish
ecosystem
- productivity
biodiversity
population
- competition, predation, habitats,
individuals
- growth, reproduction,
stress, contaminants
cell/tissue
- FA content
Fig. 1. Position of shellfish communities within the ecosystem at various integration
levels, as discussed in the theme session on shellfish – ecosystem linkages.
ENVIRONMENTAL QUALITY MONITORING AND
IMPROVEMENTS
D. McCoubrey
New Zealand Food Safety Authority, P O Box 1254, Auckland, New Zealand. E-mail:
[email protected]
Internationally there is growing concern about the degradation of the environment.
Pollution and eutrophication of marine waters and shellfish is a serious problem with
high costs to all of society.
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Bivalve shellfish, being filter feeders, are able to act as sentinel indicators of marine
pollution and will readily show the effects of heavy metals, microbial pollution and
marine biotoxins. Before shellfish can be safely consumed as a food source, it is
important that pollution be controlled. However, shellfish can also aid in cleaning up
pollutants. In Sweden, according to an EC-legal assessment, it is possible to exchange
the nitrogen removal in a sewage treatment plant by mussel farming if the same nitrogen
can be removed through the harvest of the shellfish.
Not all industry causes the degradation of shellfish resources and sometimes it is possible
to set up a symbiotic relationship. For example in Norway it has been found that the
artificial upwelling caused by the discharge of water from a hydropower plant actually
enhanced phytoplankton production and stimulated diatom growth. This in fact may
have great potential for restoring primary production and the thus the carrying capacity of
mussels in fjords affected by hydropower plants.
Therefore, to improve the environment it is very important to understand the all
ecological features specific to the shellfish resources in the area. These features include
physical geography, social influences, industry practices, historical sampling information
and the government policy factors.
Science and research play an important part in the policy cycle. So often the success of
an environmental remediation project will depend upon political policy decisions of other
stakeholders. Uptake of scientific advice will depend on identifying the problem,
correctly framing the questions for science to address along with good communication
and trust between scientists and policy makers.
It is recommended that before a project is undertaken to remediate the shellfish
environment that the following points be considered:
1) Know clearly what the remediation aims are e.g. simply shellfish populations in an
estuary through to shellfish safe enough to eat, etc.
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2) Decide how you will measure success using scientific parameters. Then baseline and
improvement measurements can be obtained.
3) Know and understand the role of other stakeholders involved in the area.
4) Use good science – it should be credible, legitimate and salient.
5) Be able to communicate your aims and needs to all audiences e.g. the public, lobby
groups and other scientists.
6) Be prepared to mediate and adapt to reach your ultimate aims.
HISTORICAL CONSIDERATIONS IN SHELLFISH MANAGEMENT
G. Flimlin1 and J. Prou2
1
Rutgers Cooperative Research and Extension, 1623 Whitesville Rd Toms River, NJ
08755 USA E-mail: [email protected]
2
IFREMER, 17390 La Tremblade, France. E-mail : [email protected]
"Progress, far from consisting in change, depends on retentiveness. Those who cannot
remember the past are condemned to repeat it." (George Santayana, The Reason of Life,
1905).
The intent of this conference is to bring together international scientists to discuss their
efforts in the realm of shellfish restoration. Science is the building of knowledge on the
knowledge that has preceded it. This particular session examined hard clam, oysters,
scallops and mussels in both the US and France.
The session keynote talk by Gef Flimlin from Rutgers Cooperative Research and
Extension in New Jersey USA with John N Kraeuter from the Rutgers Haskin Shellfish
Laboratory also in New Jersey addressed hard clam aquaculture and the historical
perspective that created the industry that extends from Maine to Florida in the US. The
presentation identified the techniques that are used from the hatchery to harvest to
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husband the hard clam, Mercenaria mercenaria, and explain why it is one of the most
important aquaculture fisheries of that area. Essentially the industry evolved in response
to reductions of wild stocks that had been reduced in almost all East Coast estuaries
because of anthropogenic impacts of over harvest linked with pollution, stemming from
population growth along the coast.
This shellfish aquaculture industry has become a link between commercial culture and
the restoration process since practically all of the hard clam seed used in restoration
projects are the product of these same hatcheries. The hatcheries have also provided
information and assistance to the towns which have established their own hatcheries or
nurseries to initiate their own programs. One of the benefits of the commercial hard clam
culture industry is that although it remains fairly anecdotal information, it seems that the
increase of the notata strain of the hard clam has been more noticeable in areas around
planted beds. Growers also feel that their aquaculture areas are also major areas of
increase habitat for macroalgae and lower parts of the food chain and that the clams in
production are also removing large quantities of nitrogen from the estuarine waters.
In Southwest Florida, efforts are underway to evaluate oyster reefs. John Stevely of
Florida Sea Grant College Program in Palmetto, Florida USA presented information
about oyster reef restoration in that area.
Logically, but not always the most obvious place to start, the scientific community turned
to historical data to understand where the original oyster reefs were located and how they
changed over the past 120 years through coastal development. By understanding what
the extent of the reefs were, they were able to set reasonable goals for restoration. They
realized that oyster reefs had tangible benefits of structure for other organisms and as
filter feeders in their system. Fortunately they were able to find documentation which
clearly identified the reef sites through a long period of time and measure and digitize
those areas, converting that data in GIS for comparisons through time. Interestingly
enough, it was discovered that the total area of oyster reef had not decreased but
increased by about 20%, although not in the same areas as shown on the early maps.
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Changes in the waterway from dredging and upland impacts on the watershed may have
provided changes in parts of the bay which made natural oyster reef production possible.
It should be noted however that this is an isolated case that may only work for this
specific site, but it proves that understanding the history of the area is imperative to
understand what needs to be done for the future.
The focus then changed to the northern coast of France in the Brittany region specifically
Mont-Saint Michel Bay. P. Le Mao of IFREMER in Saint-Malo with his colleagues C.
Retiere and C. Le Bec discussed the changes from shellfish fishing to farming and the
changes of appropriating resource for commercial harvest to modeling the space for
aquaculture.
At the beginning of the last century, the only modes of shellfish exploitation in the MontSaint-Michel bay were the fishing of cockles Cerastodema edule on the mudflats and the
native oysters Ostrea edulis fished by dredging on sub-tidal soft substrates, sometimes
followed by a stocking on 110 hectares of parks on inter-tidal flats.
After a period of decline and almost disappearance during the first half of the last
century, the exploitation of shellfish restarted after the World War II and very quickly
became a considerable presence in the bay, with very consequential development of
shellfish farming (native and pacific oysters, mussels).
These practices led directly and indirectly to a significant modification of the general
functioning of the bay ecosystem with a massive usage of the area between 5 meters
above and below the most low tide level, mainly in the Bay of Cancale. Not only did
shellfish growers monopolize and created new spaces by installing shellfish culture
structures (bouchots and oysters tables), but these activities may have introduced several
invasive species such as the slipper limpet, Crepidula fornicate which now presents a
biomass more than 7 times high as the cultivated shellfish, and also the manila clam
Ruditapes philippainarum and the pacific oyster Crassostea gigas. However, the Pacific
25
oyster, the blue mussel, Mytilus edulis, and the European flat oyster, Ostrea edulis, are
major culture species at present.
These modifications acted on the trophic structure and on the production potential of this
benthic ecosystem. The growth of shellfish farming needed to be balanced with other
characteristics of the bay such as the physical (hydrosedimentology) and biological
characteristics which were the result of modification and creation of habitats. This acts
on the biodiversity of the Mont-Saint-Michel Bay. Now the balancing of the various uses
of the bay must be incorporated into the overall management of the area.
Next O. Levasseur from CNRS/MNHN in Rennes, France discussed the natural oyster
beds of France, evaluating the management policies of the past two centuries.
He explained that French management of its natural oyster beds represents a particularly
clear example of how relationships with marine resources began to change in the
eighteenth century. In the face of dwindling harvests, the perception grew that the
resource would effectively be used up. The resulting alarm caused authorities to seek
solutions that unfortunately proved effective only in the short term. The authorities
sought two logical resolutions to the crisis. These included protecting the natural oyster
beds from over exploitation while at the same time seeking scientific solutions to
eliminate the constraints imposed by the natural reproduction of oysters through the
implementation of artificial methods of production.
In the 1750’s there was a declining harvest from the natural beds in Arcachon, Tréguier,
and the Bay of St. Brieuc. This may have been caused by dredging impacts, disregard for
shellfish spawning periods or illegal poaching. This produced the first ordinances and
laws relating to shellfish. However the results were poor maybe because they were
implemented too slowly or they were ignored as conditions improved slightly. However
when another crisis occurred in the 1770’s to 1780’s, it started a major state investigation
in 1786.
26
In 1858 Victor Coste began “Oyster Culture” experiments in the Bay of St. Brieuc, Rade
of Brest, Arcachon and on the Mediterrenean coast. Most of the experiments failed due
to inexperience, poor equipment, bad weather conditions and poaching. Nevertheless,
this period is considered the birth of contemporary French oyster culture and it
introduced methods that would be imitated in many other European countries.
In 1920-1921 a major epizooitic eradicated the European flat oyster, Ostrea edulis, from
the main natural oyster beds. This had many major social consequences.
Following this there were other problems which eventually led to the infusion of
governmental funds to help the industry survive and grow.
Through the study of these periods, covering nearly two centuries, it is possible to follow
the impacts and to learn from them. Finally through study of both the successes and
failures of management strategies, there is an attempt to arrive at some conclusions as to
the validity of any coherent policy during the entire period concerned.
The final talk of the session was by Spyros Fifas and Pierre Arzel of IFREMERSTH/UDPP in Plouszane, France. Dr. Fifas presented their work on the Management of
Scallop (Pecten maximus) Fisheries in Northern Brittany, Population Patterns under
Temperature Effect and Catch Capacities of the Fishing Fleet.
The history of the scallop fisheries of the North-East Atlantic was mainly regulated by
two factors after the World War II. The first was the hydro-climatic component: scallops
may have benefited significantly because of water temperature increases and global
warming. The second was the coastal and inshore fishing activities targeting these
species. These activities have been characterized by significant technological changes
(from generalized motorization of vessels to computer processing on board) for the last
50-60 years inducing a continuous increase of harvesting capacities.
27
Even if scallops had a more symbolic than commercial position before the 20th century,
they were fortunate to have positive combination of both factors cited above. They
became the most symbolic molluscs of the European fisheries.
Two Scallop beds of Brittany (Bay of Brest, Saint-Brieuc Bay) were analysed. Both
stocks present different features of demographic pattern as well as for fishery
development. The Bay of Brest held the primary position during the first period, but it
didn’t undergo unregulated mechanization. Fishing of young scallops (almost 30% at the
age of one year) had not been so strong anywhere else; furthermore, catch capacity had
been developed where favorable population dynamics at the start of 50’s kept resource
managers from seeing that the stock had declined gradually.
After the severe winter of 1963, the Saint-Brieuc Bay and the Channel fisheries took over
because of good environmental conditions. More strict regulation has been tried for
selectivity of fishing gears and minimum market size. However, catch capacity grows
continually and an irreversible status of population collapse was avoided at the end of
80’s.
At present, traditional regulatory policy seems to be insufficient because of computing
and technology developments on board. And yet, just restricting the number of fishing
hours is not enough. With regulations based solely on biology only a little profit is
possible, since the economic over-harvesting capacity of the fleet has already been
reached.
The session set the stage for many other talks that built on the nuances of shellfish
restoration throughout the world.
SOCIO-ECONOMIC, POLICY, OUTREACH AND EDUCATION
ASPECTS OF SHELLFISH/HABITAT RESTORATION
28
S. Macfarlane
Coastal Resource Specialists, PO Box 1164, Orleans, MA 02653 USA. E-mail:
[email protected]
By definition, the session on the socio-economic, policy, outreach and education aspects
of shellfish habitat restoration was diverse. Notwithstanding the diversity, several
themes ran through the session – one in context of the material presented and the other
with the presenters themselves.
The first theme explored the concepts of integrative policies when dealing with shellfish
restoration. Projects that demonstrated a high degree of communication with other
stakeholders, multiple partnerships, multi-disciplinary approaches and an understanding
of social sciences as well as biological sciences seemed to be the most effective.
The initial plenary presentation (this author’s) described changes over time in a small
town as an example of how recognition of land use factors and political/social and
economic realities have been important components of shellfish restoration. Several
papers that followed described projects that integrated consideration of factors other than
biology – the social context, and political realities of the place where the project was to
take place and economic factors that drove the project. Two papers dealt specifically
with economic aspects. In one, project proponents established a scallop fishery for target
user groups – both commercial and recreational. Through survey techniques, they were
able to demonstrate an economic advantage to the community as a whole for the fishery
since many users came to the community specifically to fish for scallops creating a
multiplier effect to ancillary businesses in the community – restaurants, hotels, fishing
gear etc. By advertising the economic benefits of the fishery, additional users paying a
fee could keep the stocking program viable. In another example, the fees collected from
the users directly kept the program going and again, by advertising the advantages, the
community reaped the benefits.
29
One speaker told of growing a species of oyster that was threatened but not endangered,
as a target species to restore populations to maintain biodiversity. With global species
diversity dwindling, this approach is laudable though the presenter did not explain longterm funding realities but alluded to potential problems in that arena.
One researcher examined the economic advantage of polyculture, in this case, growing
mussels with salmon or macrophytes such as kelp. The thrust of his presentation was
with mussel culture however and the economic model was developed with mussels.
Since salmon culture has created critics of the practice because of perceived and actual
pollution from feed supplies as well as from the fish, in order for the culture to be
sustainable, we need to find ways to mitigate the pollution. Polyculture may prove to be
economically and biologically synergistic.
Throughout the session, the integrative management approach was outlined in various
forms. Several speakers presented information relative to the importance of including
diverse stakeholders to the table to resolve issues even when members of a group rarely
communicate with one another. Utilizing an ecosystem approach rather than focusing
specifically on the biological requirements of the shellfish being cultured as well as an
integrative management approach, where the diverse stakeholders become part of the
project was amplified. Additionally bringing the biological realities to land-use planning
efforts was seen as a major component of mitigating the effects of land use on the
estuaries. Management of sectors by both productivity and biodiversity helps to provide
sustainability and viability but it takes all voices to be heard.
The second major theme revolved around the speakers themselves and can best be
summed up by enthusiasm. For the entire session, the room was infused with
enthusiasm, but those speaking on two often overlooked segments of the population –
school children and volunteers – showed what can be accomplished with dedication and a
willingness and eagerness to attract the attention of these population segments. In one
case, a group established a two-week biology school for middle-age youngsters (about
age 14). They had some sort of aptitude to be included in the program and the presenter
30
was honest in his assessment that there was no way to track the benefit of the program
immediately, but surveys have consistently shown that a particular teacher or experience
often propels students in a certain direction. There was hope that some of the students in
the program would be presenting at a future ICSR meeting in a decade or so.
A second presentation showed the development of a series of educational materials from
books to CDs aimed at different age groups to examine the life history and complexity
surrounding the decline of the queen conch that has been overfished throughout most of
its range. From cartoon characters to sophisticated biology, all the concepts were
included in an ambitious educational campaign.
The third presentation dealt with community efforts at shellfish restoration and included a
program that utilized volunteers, mostly retirees from Delaware, USA, to create a water
quality monitoring group and an oyster gardening group. Just three years old, the
program has multiple partnerships for funding, technical expertise, and community
responses and nearly 60 sampling stations in two separate bays. Project proponents
spoke to the ancillary benefit of education in this type of program where the general
populace becomes educated about issues in the estuary and what they, as individuals can
do to help solve the problems.
It was evident that coordinating such efforts takes a certain type of person with a love of
the subject and an enthusiasm integrated in the programs that “rubbed off” on
participants.
RECOMMENDATIONS:
The group did not discuss recommendations per se but it seemed evident through the
presentations that several recommendations can be made with respect to this broad topic.
•Integrate approach to shellfish restoration with many stakeholders and take into
consideration social, political and economic ramifications of project;
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•Design programs utilizing ecosystem and integrated management approaches for holistic
solution to problems;
•Use educational systems whenever possible to teach future stakeholders better
understanding of ecosystem and role of shellfish in maintaining healthy ecosystem.
INTEGRATED AND CONCERTED APPROACHES OF SHELLFISH
RESTORATION AND ENHANCEMENT
T. Landry
Department of Fisheries and Oceans, Science Branch, Gulf Fisheries Centre, P.O. Box
5030 \ C.P. 5030, Moncton, NB, E1C 9B6 Canada E-mail: [email protected]
In Canada, shellfish restoration activities are commonly justified on the basis of potential
benefits to the coastal habitat and the local economy; another good reason for restoring
shellfish stocks is to uphold subsistence fisheries conducted by the First Nations People.
Regardless of the underlying justification for a restoration project, the monetary costs can
be minimized by adapting an integrated approach involving the coastal communities and
definite stakeholders (e.g., recreational fishers, aquaculture industry, and agriculture
industry). In this framework, attention should be directed at activities that have impacts
(either positive or negative) on existing shellfish populations. An implementation of
ensuing management strategies would likely augment stock levels by a factor comparable
to those obtained through traditional shellfish restoration activities (seeding and habitat
modification). A well-balanced combination of the community-integrated and traditional
approaches would possibly maximize stock levels.
With respect to the community-integrated approach, the benefits of improving fisheries
management should be fully addressed at future ICSR conferences. The negative effects
of mismanaged fisheries are obvious when fisheries target vulnerable shellfish stocks.
However, other fishery-related effects are less obvious (or known). The impact of fishing
32
gear on both targeted and non-targeted species needs to be considered in greater details.
For instance, bioeconomic simulations indicate that improving gear selectivity for the
Nephrops fishery in the Bay of Biscay, France, would result in ecological and economical
benefits from a restoration perspective (Macher et al.). The impact of fishing activities
on predatory or competing shellfish species should also be taken into account. The
structure of the predator community may influence the outcome of restoration initiatives,
as was presented by Seitz and Lipcius in regards to oyster reef restoration projects in
Chesapeake Bay, USA. Although predator and competitor populations fluctuate
naturally, they can be controlled using either targeted- or by-catch-species management
strategies. Therefore, shellfish restoration activities could benefit from a proper
management of fisheries that implicate predator and competitor species.
The role of shellfish aquaculture for restoring the ecological function in coastal systems
has been discussed at previous ICSR meetings. More specifically, the topic of
management of aquaculture activities was addressed at the ICSR05. Policies on lease
transfers and management can have an impact on their ecological roles. This topic could
be explored more deeply, certainly in the context of community aquaculture projects.
Thereafter, the transfer of knowledge to private aquaculture operations could be more
efficient.
FISHERIES AND AQUACULTURE MANAGEMENT
D. McLeod
Association of Scottish Shellfish Growers, Mountview IV45 8RU Ardvasar, UK. E-mail:
[email protected]
The session clearly identified an almost symbiotic relationship between the restoration
process and the adjacent activities of fisheries and aquaculture, in particular the latter.
33
One example described was the interactions between suspended mussel cultivation and
rock crabs in PEI, Canada.
The concept of restoration being a wider process than ‘specific species for specific
species’ appeared to be generally accepted, while the contribution of aquaculture to
molluscan restoration was highlighted, in terms of :
Passive or as a by-product of normal cultivation operations, for example release of seed
or spat into the wider environment from the mature farm biomass thereby generating
incremental settlement within both the lease area and beyond in the ‘wild’, and in the
marketplace, where aquaculture supplies of molluscs reduce consumer demand on
supplies from the capture fishery thereby reducing the likelihood of over-fishing;
Active, with direct restoration efforts based on aquaculture facilities, for example from
hatchery supplies with ‘improved’ restoration stock as a result of selective breeding (for
positive characteristics), with higher survival rates than in nature and an increased
frequency of spawning.
The introduction of facilitating technology, such as artificial reefs, was recognised and
supported as a potentially useful tool in the process of restoration, with positive results
from a project in Chesapeake Bay. Similarly the importance of surveys and a multidisciplinary approach to identify trends in natural stocks and stocks under pressure was
identified as a priority action for practitioners, scientists and regulators, with examples
from Senegal, Ireland and Washington state.
The review and commentary on the shellfish sector in Korea highlighted the impact of
disease on the industry, and the need for monitoring of populations as a method of
preventing stock collapse.
In summary, the session recommended the promotion of closer working relationships
between shellfish cultivation, fisheries management and restoration interests in
recognition of the frequent commonality of interest, eg in research topics – however this
34
would require an acknowledgement by the restoration lobby that economic viability is an
essential element of sustainability (part of the title of the Conference!).
‘Restoration’ support for aquaculture developments would balance the benefits that flow
to that interest group from a closer association with aquaculture, namely improved
credibility, greater economic/political leverage, increased access to funding, as well as
the practical dimension of enhanced remote settlement.
Working together, shellfish cultivation, fisheries management and restoration interests
should promote mutually beneficial activities at appropriate political, economic and
scientific fora, in order to optimise future shellfish sector contributions to economic
growth, wealth creation, consumer nutrition and health, and ecosystem resuscitation.
35