Chemical differences in the blood of yellow and silver phases of the european eel ("Anguilla anguilla" L.).

Abstract

Physiological changes occur when eels transform from yellow phase into silver phase. The silver eels show increased activity, cessation of feeding, and mobilization of the tissue energy reserves to be used for migratory swimming and for the growth of the gonads. Some of these changes may be reflected in the chemical composition of the blood in different eel stages. The purpose of this investigation has been to find out whether any marked differences may be observed in the blood chemistry between yellow and silver eels captured from the same locality.