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Impacts on commercial species


Catch with flatfish and cod. Photo: T. Otto (BfN)
Catch with flatfish and cod. Photo: T. Otto (BfN)

Some three million tonnes of fish, shellfish and crustaceans are caught each year in the North Sea alone, making this one of the highest-yield marine regions anywhere in the world.

As in other marine areas, many stocks in the North Sea and Baltic Sea are fished above maximum sustainable yield (MSY). MSY is the catch quantity that does not endanger stock replenishment while securing high yields for the longer term. This is an express objective of the recently reformed EU Common Fisheries Policy (CFP).

Severe negative impacts on the ecosystem

Fisheries are among the human activities with the most severe negative impacts on the marine ecosystem. Those impacts include:

  • Depletion of numerous commercially exploited fish stocks;
  • Changes in ecological communities – bycatch of juvenile fish and non-target species alters the composition of fish communities;
  • Destruction of benthic communities – most of all, fishing with mobile, bot-tom-contact fishing gear (such as otter trawls, beam trawls and dredges) of the kind widely used in the North Sea has major adverse impacts on benthic habitats such as sandbanks and reefs with their characteristic eco-logical communities. The extent of harm done depends on the fishing gear, its weight, the tow speed, the habitat type and the species involved. Slow-growing species and older organisms such as sea urchins and sea anemo-nes around reefs can be irretrievably destroyed. Species that do not reach maturity until several years of age and that only have few offspring are especially sensitive to the impacts of fishing and can be wiped out com-pletely if fishing intensity is too excessive.

 
 

Directorate Marine Nature Conservation

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