Recommendations to investigate the potential for stock enhancement and

restocking programmes for the sustainable use of marine living resources within
the European multinational context

Ecosystem-based Stock Enhancement Workshop

Provincial Court, Bruges, Belgium, 7-8 May, 2007

Introduction

There are concerns about the sustainability of the world’s capture fisheries at the
current total level of production at about 96 million tonnes/yr. The warning signals are
an increase in the proportion of depleted or recovering stocks, from ~10% in 1974 to
28% in 2004, and a corresponding decrease of under- to moderately- exploited stocks
from ~40% to 24% (FAO, 2004). It is widely acknowledged that reductions in fishing
effort and restoration of fish habitats are needed to improve resilience of capture
fisheries. Concurrently, aquaculture is experiencing tremendous increase in production
and for some coastal fisheries, application of aquaculture technology through stocking
(for definitions see Annex 1) show promise to help restore lost production (e.g. European
lobster stocking in Norway (Svåsand et al, 2004), and red sea bream in Japan (Ref…)),
and possibly increase harvests beyond historical levels.

Within Europe the combined fishery catches and aquaculture production of the present EU
member states was 7.3 million tonnes in 2003, comprising 5% of the total world production
(3rd after China and Peru). The volume of fish landed in the EU fell by 27% between 1995 and
2003. With an annual growth rate of 4% over the past decade (which is below the global
average of about 9%), aquaculture has been one of the fastest growing areas in the food sector
with an annual yield of 1.4 million tonnes in 2003 or an increase of 30% as compared to 1995.
The value of the member states' production is currently about € 3 billion per year to which an
extra 2 billion can be added for associated country Norway. Aquaculture constitutes about
19% of the volume and 30% of the value of the total EU fishery production. The EU
continues to be the largest single import market in the world (approximately 8 million tonnes
worth 19.4 million € in 2001) and consequently there exists a significant trading deficit.
Imports in 2003 increased to 63% of total whitefish volume, from 59% and 55% in the two
previous years. Between 1994 and 2004 the deficit of the seafood trade increased from 3.7 to
5.6 billion Euros, representing 3.2 million tonnes of raw products. Average EU consumption
stands at 22.7 kg/head/year which are higher than the global average. In addition, recreational
fishing is emerging as important activity in coastal and marine areas and is making significant
contributions to local economies. Unfortunately many marine and coastal fisheries are under
pressure and in decline, and the need for more fish and fish products cannot be met by capture
fisheries alone. There is scope for increased production through appropriate application of
aquaculture technologies and specifically through stocking of aquatic animals into coastal and
marine areas.

It is recognized that many marine and coastal capture fisheries are under pressure and in
decline, the European Union represents a tremendous market for fish and fishery products,
and the release of juvenile fish has in some cases been a successful management strategy to
increase production and profit from fisheries. The issues to be addressed are how to integrate

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stocking programmes within fishery management programmes, the long term impacts of
released fish on aquatic ecosystems and how to evaluate accurately the full cost and benefits
of the stocking programme. The goal of these recommendations is to assess the role of
stocking as a tool to develop and maintain sustainable capture fisheries of native species in the
marine and coastal environments of Europe.

Stock enhancement and restocking are fisheries management approaches involving the release
of cultured organisms into natural fish populations (Bartley & Bell in press). Such approaches
have the potential to:
 Understand ecosystem dynamics
 Conserve biodiversity
 Rebuild stocks
 Provide partial mitigation for ecosystem effects of fishing
 Increase production and profit from commercial and recreational fisheries
 Integrate disciplines such as: marine ecology, genetics, aquaculture, fishery
management, socio-economics, legislation
 Transform management systems with more participation from stakeholders
 Increase public awareness
 Provide new opportunities for fisheries-related livelihoods

For enhancement initiatives to contribute effectively to fisheries management goals, they

require integrated management approaches accounting for interactions and tradeoffs between
stocking, harvest regulation, and other conservation measures (Lorenzen 2005). New
institutional arrangements for management are often required, and enhancement initiatives
can provide the impetus for management system transformations with far-reaching benefits.
Innovation may be required in multiple areas, and this will require and facilitate constructive
engagement of fishers, government, and other stakeholders (Lorenzen in press). Stock
enhancement approaches provide new opportunities for fisheries management, but are also
associated with significant ecological and economic risks. It is therefore important to adopt a
responsible approach that remains objective about the scope for restocking and stock
enhancement to add value to other forms of management. In particular, (1) goals for stock
enhancement programmes must be explicitly stated in terms of desired benefits and purposes;
(2) programmes must be scientifically defensible, i.e. take into account ecosystem level
considerations; and (3) hatchery-release programs must respond adaptively to new
information (Myers et al., 2004). Although much progress is being made, application of this
technology still has a long way to go before integrated management systems are in place that
successfully address all the biological, ecological, social, cultural and economic issues
(Bartley and Bell, in press). The main challenges include: identifying when and where to use
the interventions to add value to other forms of management; integrating these initiatives with
institutional and fisheries management regimes; monitoring success of the interventions;
producing cultured juveniles cost-effectively; and releasing them in the wild so that they
survive in high proportions.

Research priorities

Four research priorities have been identified to guide future research activities:

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 1) Improve knowledge of the European marine and coastal environment for a better
understanding of the population structure and dynamics of commercial and non-
commercial species.

2) Integrate stocking practices with ecosystem-based management supported by socio-

economic research and participatory management strategies.

3) Development of concepts, tools and methods to assess the suitability of restocking and
stock enhancement of key commercial species.

4) Improve aquaculture technologies and methodologies to meet the demands of stocking

programmes that will have minimal adverse environmental impacts.

To develop the necessary high quality and policy relevant research, attention should focus on
specific research topics such as:
 Develop procedures on how to prioritize stocks where stocking can have impact on
fishery production/profit and should include:
o Suitability of species based on life history characters
o Appropriateness of stock assessments that are available
o Appropriateness of data on ecosystems and species biology
o Identification of major bottleneck– decoupling fishery impacts from
environmental impacts
o Suitable habitat exists or can be rehabilitated
o System of fishery management and governance exists
 Evaluate the role of stocking as a fishery management tool
o How to integrate stocking with fishery management
o Refine spatial scale of stock assessments to be more appropriate for stocking
programmes
o Develop appropriate quantitative assessment methodologies for rebuilt or
enhanced fisheries
o Review the interaction between stocking and conservation measures on
limiting fishing capacity and TAC
o Analyses of policy and legal issues
 Analyse risk and uncertainty
o Genetics
o Diseases
o Other ecological interactions and impacts
 Identify appropriate monitoring methods
o Further development of useful tagging systems
 Identify indicators for monitoring effects of stocking on:
o Biology of released organisms
o Ecosystem
 Develop appropriate tools for social and economic evaluation of stocking programmes
o Commercial fisheries
o Recreational fisheries
o Ecosystem goods and services
 Identify appropriate release strategies and develop protocols

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  Understand ecosystem processes including carrying capacity in marine and coastal
areas and how they are changing in response to human and natural events, e.g. climate
change, and in light of multiple use.
 Understand the adaptive function of genes and genomes, i.e. ecological genetics.
 Improve and adapt aquaculture technology to meet the criteria and demands of
stocking programmes such as
o Feed sources and practices
o Breeding practices
o Development of protocols for producing novel species for release
o Disease management
o Life skills conditioning
 Elucidate consumer perception

Implementation strategy

The above research needs should be addressed on eco-regional scale by activities such as
stakeholders meetings, workshops, and the development of desk studies and case studies. As
a priority, a two-step stakeholder consultation is required.
 An initial stakeholder consultation should be organised to prioritize areas and species
for stocking. As a background for this consultation, desk studies and a review of the
state of the art in disciplines related to stocking will be required. As a follow-up to the
consultation, assessment of stocking potential will be determined.
 A second stakeholder consultation should be organised to analyze results of the
assessment and agree on areas and species to be prioritized and prepare the research
agenda.

The outcome of this research should contribute to ecosystem-based fishery management and
integrated ecosystem management with the context of the EU Maritime Strategy.

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Annex 1 - Terminology and concepts

Terminology is this field is non-standard and may lead to confusion in planning activities,
setting objectives and evaluating the efficacy of the activity. Table 1 defines key terms that
have been agreed by the 3rd International Symposium on Stock Enhancement and Sea
Ranching (web-site).

The objectives of using any of the 3 types of stocking listed in Table 1 in fisheries
management must also be clearly defined (Cowx 1994) before decisions are made on fishery
management interventions. Cowx (1994) identified 3 main categories of stocking (Table 2).
Although similar, each has important differences that must be addressed.
A clear understanding of the type of stocking being undertaken, the objectives of the stocking
and the key assumptions will help guide fishery management interventions. A common
assumption to all types of stocking is that consumers will accept released fish.

Table 1. Terminology (Bartly and Bell, in press)

Restocking involves releasing juveniles into a wild population to restore severely depleted
spawning biomass to a level where it can once again provide regular, substantial
yields
Stock enhancement is designed to increase productivity of an operational fishery by augmenting the
natural supply of juveniles, and optimising harvests, by overcoming recruitment
limitation
Ranching involves the release of juveniles into unenclosed coastal environments for harvest at a
larger size in ‘put and take’ operations. There is no intention of allowing released
juveniles to augment spawning biomass, as in restocking, or to strengthen year
classes, as in stock enhancement. However, where the animals reach maturity before
the desired harvest size, they will also contribute to egg production.
Recruitment limited Recruitment is considered to be limited when the natural supply of juveniles fails to
reach the carrying capacity of the habitat. This often results from great variation in
larval or juvenile mortality, even when there are adequate numbers of breeding adults.

Table 2. Objectives of “stocking” (after Cowx 1994 and Bartley 1999)

Type Species stocked Rational Key assumptions
Mitigation Native or close relative To make amends for Habitat can support release and is
some damage to system below carrying capacity; fishery is
recruit limited. Consumers accept
released fish.
Augmentation Native To improve production Habitat is below carrying
and profit over natural capacity; fishery is recruit limited;
conditions released and wild relatives
compatible. Consumers accept
released fish.
Community Alien To improve production Species performance in new
change and profit over natural environment acceptable; habitat
conditions below carrying capacity; resource
base will not change substantially.
Consumers accept released fish.

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Annex 2: Responsible approach and ecosystem approach

Recommendations & Guidelines

One of the goals of this working group is to promote scientific discussion

that will lead to the development of guidelines, recommendations and codes
of practice for Responsible Stock Enhancement. One of the first objectives of
the group was to publish a platform paper to focus attention to the question,
"what is a responsible approach to stock enhancement?" Toward that end
the following guidelines have been proposed for further considerations. This
approach prescribes several key components as integral parts in developing,
evaluating, and managing marine stock enhancement programs. Each
component is considered essential to control and to optimize the
effectiveness of hatchery releases in helping to conserve and expand natural
resources.

GUIDELINES FOR A "RESPONSIBLE APPROACH" TO STOCK

ENHANCEMENT (source: Blankenship and Leber, 1995. American Fisheries Society
Symposium 15:167-175)

 Establish methods for prioritizing and selecting species to be enhanced

 Create a management plan with long and short term goals, harvest regimes and genetic
conservation objectives.
 Incorporate life history and ecological attributes into enhancement strategies and
tactics.
 Create a genetic resource management plan to minimize inbreeding/ outbreeding
depression and to conserve genetic resources.
 Create a disease and health management plan.
 Define and use an empirical process for determining optimal release strategies.
 Define and implement means to identify hatchery- produced fish.
 Define quantitative measures of success, and assess the enhancement project in terms
of stated objectives in the management plan.
 Define and evaluate socio-economic objectives.
 Use adaptive management principles to evaluate and improve management strategies
and tactics.

Each of these points is considered in greater detail in Blankenship and Leber (1995).
Munro and Bell (1997) give a good summary of how several of these points are being applied
by various stock- enhancement research programmes. See related papers by Peterman (1991),
Cowx (1994) and Hilborn (1999). The references for these papers are:

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Literature cited

Bartley, D.M. (1999). Marine Ranching: a global perspective. Chapter 6. in: E. Moksness, T.
Svasand and B. Howell (eds). Stocking and Sea Ranching. Blackwell Science, London, 79-90

Bartley, D.M. and J.D. Bell. (In press). Restocking, stock enhancement and sea ranching:
arenas of progress. Reviews in Fisheries Science.

Blankenship, H.L., and K.M. Leber (1995) A Responsible Approach to Marine Stock
Enhancement. In H.L. Schramm Jr. and R.G. Piper (eds.), Uses and Effects of Cultured Fishes
in Aquatic Ecosystems. American Fisheries Society Symposium 15:167-175.

Cowx, I.G. (1994). Stocking strategies. Fisheries Management & Ecology 1: 15-30.

FAO. The State of World Fisheries and Aquaculture. (2004). FAO, Rome. (also available at
ftp://ftp.fao.org/docrep/fao/007/y5600e/y5600e00.pdf)

Lorenzen, K. (in press) Understanding and managing fisheries enhancement systems.

Reviews in Fisheries Science.

Lorenzen, K. (2005) Population dynamics and potential of fisheries stock enhancement:

practical theory for assessment and policy analysis. Philosophical Transactions of the Royal
Society B, 360: 171-189.

Myers, R.A., S.A. Levin, R. Lande, F.C. James, W.W. Murdoch, and R.T. Pain. (2004).
Hatcheries and endangered salmon. Science 303: 1980.

Svåsand, T, Agnalt, A.L., Borthen, J., Heggberget, T. and Skilbrei. O. S. (2004) An integrated
development programme for marine stocking: the Norwegian example. In: Marine
ranching (eds. Bartley., D.M and Leber, K.M.) FAO Fish. Tech. Paper, 429 19-72.