Aquaculture for all

Effective Management for Sustainable Shellfish Stocks

Crustaceans Sustainability Clams +6 more

The sustainable management of shellfish needs a long-term strategy to apply precautionary approach concepts to shellfish stocks, writes TheFishSite editor in chief, Chris Harris.

Delivering the Drummond Lecture 2011 at the Shellfish Association of Great Britain annual conference, Dr Colin Bannister said that scientists and those within the shellfish industry needed to develop agreed formal long-term management plans.

He said there is a need for a sustainable approach similar to the one used in the fin fish industry developed by the International Council for the Exploration of the Sea (ICES).

The precautionary approach, which was included in guidelines from the Food and Agriculture Organisation of the UN in 1995 laid down advice for a management process, desirable predetermined targets and limits, a specified harvest strategy and rules to respond to the changes in the status of stocks.

Dr Bannister told the conference in London that although the FAO 1995 guidelines are not legally binding, but they are the basis for applying the precautionary approach to sustainability in most international scientific and management bodies including EU & NEAFC, which is advised by ICES, and NAFO.

"This is a fisheries approach, but it should be used in the shellfish industry as well as in the fishery industry," said Dr Bannister.

He said the shellfish industry should look to set out maximum sustainable yields - a level beyond which fishing or harvesting can damage stocks and could lead to the decimation of the species.

"Heavy fishing means fewer fish in the world," said Dr Bannister.

He said there is an optimum for harvest rates and going over this will produce "impaired recruitment" - the point where, when all the older and larger fish have been captured and the younger fish are then harvested, the rate at which they come from the spawning stock falls below the capture rate.

He said there are famous examples where this occurred in the herring and cod industries and when the replenishing of stock falls below a certain level, then a train of collapse follows from which the stocks and even species might not recover.

"Precautionary management will stop you getting to the collapse situation," Dr Bannister said.

He said that by laying down a cap on harvest rates, the industry can achieve a sustainable yield.

He said there are many management diagnostic indicators available, but he questioned whether all the management systems available can deliver sustainability and also how fisheries and shellfisheries affect ecosystems.

"The precautionary approach and the Marine Stewardship Council Accreditation Assessment Tree raise key questions: Can the management system deliver sustainability? Is the stock actually being fished sustainably?" Dr Bannister said.

Drawing an example of Langoustine Nephrops norwegicus, Dr Bannister said that capture by trawl or creel depends on daily patterns of emergence and seasonal patterns of reproduction and the harvest rate is usually lower on females.

He added that fishery landings already limited by precautionary measures and days at sea are constrained by cod rules.

Dr Bannister said there is an international management framework for langoustine and there is routine stock monitoring and harvest rates are also subject to estimates.

He said that because harvest rates are at present close to the manageable maximum sustainable yield, the requirement for reductions is modest and the system of harvest meets many sustainable criteria.

However, he said that looking at the systems for harvesting brown crabs around the British Isles suggests that sustainable fishing requires significant reductions.

He said there has been 10 years of pressure from the Shellfish Association of Great Britain and the industry for a better and more coherent management system.

He aid there is growing industry agreement in favour of action, but not on what action to take.

"So far, management lacks the formal coherent fishery objectives, harvest strategy, and decision rules that meet precautionary approach guidelines," he said.

He said the examples and the general industry approach to sustainability require plans that contain pre-agreed objectives, harvest strategy, reference points and decision rules, or meaningful proxies, that are strong and specific.

Dr Bannister said there should be Long-term stock monitoring and ongoing research on biology and population processes.

There also needs to be an advisory process such as a National Shellfish Resource Group, or equivalent.

There is also a major requirement for effective enforcement.

Regulating orders show the joint benefits of 'control through ownership', and consensual participatory management, he said.

May 2011
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