Comparison of reproductive success of cod, Gadus morhua, from the Barents Sea and Baltic Sea

To test the hypothesis that cod do not reproduce normally in the Baltic Sea, a comparative study using cod from relatively unpolluted areas in the Barents sea was performed. During the spawning period cod were caught by trawling, then stripped and fertilised directly on the boat. The fertilised egg batches were transported to the laboratory immediately, and held under optimal conditions for cod embryo and larval development. The data obtained indicates that reproductive success is dramatically lower in cod from the Baltic Sea compared with those from the Barents Sea. The disturbances might be correlated to the female individuals rather than the males.