Black lines in the muscle of cultured atlantic cod (gadus morhua).

Black lines and spots observed in fillets have become a matter of concern for the producers of farmed cod. Whilst there is very little published material on the subject the problem is increasingly discussed throughout the industry. The phenomenon has als o been observed in other species of farmed fish with white flesh. Earlier investigators examined the significance of light exposure and similar environmental influences on the appearance of black lines without reaching any firm conclusions as to either th e cause of or the mechanisms underlying the deposition of melanin in the tissues. In this project we seek to determine the physiological mechanisms leading to excess production and inappropriate deposition of melanin. Previous studies have shown a connect ion between trace mineral nutrition, particularly with respect to copper in the diet, and the mechanisms leading to melanin synthesis. Further to these data we shall investigate the effect of copper in the diet on melanosis in farmed cod and the overall t race mineral status of farmed cod compared to wild cod.