Effects of freezing in and out of water on length and weight of Lake Michigan bloaters

The purpose of this study was to determine if freezing significantly alters the length or weight of bloaters Coregonus hoyi. Bloaters were collected from southern Lake Michigan and were frozen for periods of 2-200 d. Freezing in water caused a significant decrease in length and a significant increase in weight. These changes did not vary predictably with time. The mean change in weight was greater for adults than for juveniles, but the mean change in length was not significantly different between juveniles and adults. Regressions for weight or length after freezing versus weight or length before freezing were highly significant and can be used as correction equations for estimating the original lengths and weights of fresh specimens after fish have been frozen. Test fish that were subsequently refrozen in air shrank more than those refrozen in water.