Temperature and the recruitment of Atlantic cod (Gadus morhua)

Variability in the recruitment of fish has been attributed to either change s in the environment or variations in the size of reproductive stocks. Dise ntangling the effects of environment and stock has proven to be problematic and has resulted in recurrent controversy between studies supporting eithe r hypothesis. In the present study, we examine the relationship between int erannual changes in temperature and variation in recruitment for nine Atlan tic cod (Gadus morhua) stocks in the North Atlantic. We show that for indiv idual stocks, the relationship often appears weak and statistically not sig nificant. On the other hand, by combining in a single metaanalysis the resu lts from individual stocks, we demonstrate that recruitment of Atlantic cod is linked to interannual fluctuations in temperature in such a way that fo r stocks located in warm water the relationship is negative, for stocks loc ated in cold water the relationship is positive, and there is no relationsh ip for stocks located in the middle of the temperature range.