Cod, herring, plaice and sole in the North Sea

As a result of intensive fishing, stocks of certain commercial fish species have been under pressure for some decades. The species most at risk is the cod.

Trends in cod

Cod stocks have been falling for years. Spawning stocks are currently below the precautionary level and for 10 years have been at the limit level (these terms are explained in the Technical note). The European Union has proposed limitations to catches.

Trends in herring

A moratorium on herring fishing in the early 1970s allowed stocks of this species to recover. After fishing was resumed in 1983, stocks fell appreciably once more. They have been increasing since 1997, however, and are currently above precautionary level.

Trends in plaice

After peaking in 1989, plaice stocks in the North Sea declined for 8 years, to below the limit level. In the last 3 years there has been a slight upturn, bringing stocks to just below the precautionary level in 2000.

Trends in sole

Sole stocks are prone to major fluctuations because of occasional very strong fluctuations in numbers of juveniles. Spawning stocks are currently above the precautionary level.

Technical note

For commercial fishing to be sustainable the fish stocks must contain sufficient spawning stocks i.e. sufficient adult fish to ensure offspring. Two thresholds have been defined for the management of fish stocks: the limit level and the precautionary level. If spawning stocks fall below the limit level, the production of sufficient offspring is at risk. The precautionary level is intended to prevent the spawning stocks approaching the limit level. Once stocks fall below the precautionary level, measures must be taken to reduce the intensity of fishing. The data on fish stocks are from ICES.

References

Heessen, H.J.L., H.C. Welleman, N. Daan, A.C. Smaal en G.J. Piet (2001). Bijdrage RIVO aan Natuurcompendium 2001. Nederlands Instituut voor Visserijonderzoek RIVO. Intern rapport C058/01. IJmuiden.

ICES (2001). Report of the ICES Advisory Committee on the Fishery Management, 2000. ICES Cooperative Research Report No. 242. International Council for the Exploration of the Sea. Copenhagen.