Differential effect of formalin preservation on yolk and tissue of young chinook salmon (Oncorhynchus tshawytscha Walbaum)

Abstract

Preservation in 5% neutral formalin for periods up to 50 days differentially increased the yolk and tissue weight of young chinook salmon (Oncorhynchus tshawytscha). Yolk gained relatively more weight than tissue. As a result, intact alevins showed a net weight gain during preservation, the magnitude of which was related to the amounts of yolk and tissue present at preservation. No single correction factor was generally applicable to compensate for weight changes in preserved alevins. On the other hand, preservation had little effect on weight of intact chinook eggs, regardless of egg composition. Presumably, increases in yolk and tissue weights of preserved eggs were masked by loss of perivitelline fluid.