REPORT OF THE STUDY GROUP ON RECRUITMENT VARIABILITY IN NORTH SEA PLANKTIVOROUS FISH (SGRECVAP)

The poor recruitment in recent years (2001–2004) in planktivorous fish in the North Sea has become cause for concern for fishers, managers, and scientists alike. It has lead to fishery closures and cuts in total allowable catches in sandeel, Norway pout, and herring. SGRECVAP met to investigate and describe the serial poor recruitment, and review probable mechanisms for the recruitment trends.Time-series analysis showed that there was a common trend in the recent recruitment of all three target species. There was a strong negative trend in the stock-recruit residuals for herring and Norway pout, suggesting that the poor recruitment in those stocks is not related to spawning-stock biomass size. This was not the case in sandeel, where the situation was more complex. The common pattern of decline in recruitment seen in the planktivorous fish was not common to the major commercially exploited fish species in the North Sea. There was evidence for significant shifts of at least two periods of recruitment for the major commercial fish species exploited in the North Sea (1986 and 1996/97). Specifically for the three target planktivorous species, SGRECVAP considered there was a significant shift in recruitment in 2001.