Publication Abstract

Statistical prediction of short term changes in the recruitment of North Sea cod (Gadus morhua) using temperature forecasts

B. Planque, C.J. Fox, M.A. Saunders and T. Hamilton

Empirical evidence supports the hypothesis of a general relationship between temperature and recruitment to cod stocks across the North Atlantic. Those stocks located at the northern and southern geographical limits appear to be most influenced by inter-annual variations in sea temperature. Cod in the North and Irish Seas are near the southern boundary of their range and year-class strength is inversly related to sea surface temperature during the first half of the year, as well as to the size of the spawning stock. Management of these stocks relies upon short to medium term projections. Since these cod stocks are currently at low levels, the future trajectory of the stock biomass is strongly influenced by recruitment levels. Until now the relationship between sea temperature and recruitment has not been utilized in stock projection models used in ICES assessments. In several regions of the world, particularly the tropics, sea surface temperatures (SSTs) have been shown to be predictable several months in advance, using statistical models. We assess the skill of one such model, based on trends and persistence, to forecast North Sea SSTs out to eight months. We then evaluate the potential benefits of such information in predicting short term fluctuations in the recruitment of cod in this region.

Reference:

B. Planque, C.J. Fox, M.A. Saunders and T. Hamilton. 2003. Statistical prediction of short term changes in the recruitment of North Sea cod (Gadus morhua) using temperature forecasts. Scientia Marina, 67 (Suppl. 1), 211-218