Bioenergetics of the Southern Brook Lamprey, Ichthyomyzon gagei

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Abstract
Large fluctuations in proximate composition and energy content of the southern brook lamprey, I. gagei Hubbs and Trautman, at various stages in the life cycle have been related to the animal''s trophic status and reproduction. Protein and lipid were catabolized, the latter to a greater extent, during post-larval development. During the 8 mo. non-trophic interval which followed the commencement of metamorphosis, lipid and protein were reduced to .apprx. 7 and 45% of the absolute quantities present in pre-metamorphosing animals. The energy content of the liver and gonad was much greater in females than in males during the later stages of metamorphosis and the adult interval. Metabolic rate, calculated from changes in energy content, increased throughout the post-larval interval. In spawning animals metabolic rate was .apprx. 4 times higher than in early metamorphosing lampreys. Metabolic compensation among lampreys from vastly different temperature regimes was suggested, due to a remarkable similarity in lipid accumulation immediately prior to the commencement of metamorphosis.