Publication Abstract

The rise and fall of cod (Gadus morhua, L.) in the North Sea

R.C.A. Bannister

The recent history and current state of the North Sea cod (Gadus morhua) stock is described using the 2000 stock assessment carried out by the International Council for the Exploration of the Sea (ICES), which covers the period since 1963. This shows that the stock is heavily exploited, seriously depleted, and suffering from reduced recruitment. Under the precautionary approach framework, and as required by an EU–Norway management agreement, the ICES Advisory Committee on Fishery Management (ACFM) has advised a severe reduction in fishing mortality and the implementation of a plan to rebuild spawning stock safely and rapidly to the precautionary level. Stakeholders are sceptical about the justification for this advice and the severity of the measures proposed, and the paper discusses the issues arising from this. ACFM has consistently advised strong management, and in many years managers agreed the advised Total Allowable Catch (TAC) or even a lower one, but these have so far failed to reduce fishing mortality. Contributory factors are discussed, e.g. the problem of the mixed gadoid fishery, the weakness of TAC management, and evidence that in several years the assessment overestimated spawning biomass and hence the TAC. Current stock trends are compared with provisional literature estimates for the period back to 1920, showing that the marked increase in landings and fishing mortality in the 1960s and 1970s coincided with a major increase in cod recruitment (part of the so-called "gadoid outburst"), the possible causes of which are enumerated from the literature. Since 1987 the decline in spawning biomass to an all-time low coincides with a downturn in recruitment to the historical level, and the persistence of a high fishing mortality that is now unsustainable. To avoid collapse, the North Sea cod stock requires effective implementation of a recovery plan to increase spawning biomass and to maintain or increase recruitment. Recovery may take 10 years or more. Interim measures have been agreed in the form of a low TAC and an increase in the minimum mesh size for the gadoid fishery, but it is too soon to see the benefits of these measures, even assuming that they are complied with.

Reference:

R.C.A. Bannister. 2004. The rise and fall of cod (Gadus morhua, L.) in the North Sea. Management of Shared Fish Stocks 316-338pp