Proximate Composition of the Adult Anadromous Sea Lamprey, Petromyzon Marinus, in Relation to Feeding, Migration and Reproduction

Abstract

SUMMARY (1) The large fluctuations in the proximate composition of the muscle, liver, gonad and whole body of various stages in the adult phase of the life cycle of the anadromous sea lamprey have been related to the feeding, migration and reproduction of the animal. (2) Lipid levels were equivalent to only 1.3% of the animal's wet body weight at the end of the 10-month non-trophic period which follows the initiation of metamorphosis. (3) The relative amount of lipid rose by approximately eight times during the subsequent freshwater and marine parasitic phase, before subsequently declining to 40 after the conclusion of the upstream migration and spawning. (4) The data indicate that protein, as well as lipid, is extensively catabolized during the spawning period. (5) The lipid content of the liver is much greater in male than female upstream migrants, whereas the reverse situation is found in the gonads. (6) The increase in the weight of lipid in the ovary during the spawning migration corresponds to a value equivalent to approximately one half of the lipid reduction incurred by the whole animal. (7) Values for glycogen levels in the muscle, liver and gonad vary markedly during the