Effects of feeding coho salmon and other Great Lakes fish on mink reproduction

Abstract

Feeding experiments were conducted to investigate reproductive problems attributed to the feeding of Great Lakes coho salmon to mink. Several other species of fish were fed for comparison. Whole, raw, sexually mature coho salmon taken from tributaries of Lake Michigan were ground, mixed into a diet at a 30% level, and fed to mink before breeding and during gestation. This diet caused reproductive failure and (or) very early kit mortality. Feeding canning by-products of coho salmon from the same source and at the same level to adult mink for 3 months resulted in mortality. Reduced reproductive performance and (or) excessive kit mortality were observed in mink which were fed diets that contained Lake Michigan bloater chub, Lake Michigan yellow perch, and mature coho from the Lake Erie system. Mink rations which contained West Coast coho salmon and Lake Erie yellow perch did not impair reproduction nor result in excessive mortality.No correlation was found between the degree of oxidative rancidity or mercury contamination of the fish and the reproductive performance of the mink. The levels of pesticide residues in the fish (and the complete diets) and the degree of reproductive decline and (or) kit mortality observed in the mink appeared related.The study demonstrated that coho salmon per se does not cause the reproduction and mortality problems. Further, the disorder is also associated with other species of Great Lakes fish and appears to be dependent upon the species of fish and its environment.