Seasonal changes in plasma amino acid levels in the winter flounder (Pseudopleuronectes americanus)

Abstract

Amino acid analyses were performed on plasma samples taken monthly over a period of 2 years from 305 mature winter flounder. All plasma amino acids showed wide seasonal variations. A very low basal level of the total plasma amino acids was found during the winter months from December through until June. In July, the total levels rose from six to seven times the basal level and then stabilized during August through to November at a level three to four times the basal level. Both male and female flounder showed similar patterns of seasonal amino acid variations. These seasonal variations in plasma amino acids may be related to the feeding habits of the flounder. However, an increase in the plasma level of alanine and threonine during November correlates with the initiation of antifreeze protein synthesis.