Differences between the livers of spawning male and female sea lamprey (Petromyzon marinus)

Abstract

Migratory sea lampreys (Petromyzon marinus) were collected in spring from rivers flowing into Lakes Ontario, Erie, and Huron. Lengths, weights, liver weights, and liver colors were recorded. Livers were analyzed for fat, water, and protein content. Transmission spectra of chloroform extracts of liver pigments were also obtained. Female livers from Lake Ontario and Lake Huron lamprey were larger than male livers, whereas male livers of Lake Erie lamprey were larger than female livers. In all three samples female livers developed a green coloration more rapidly than did male livers, as a result of a more rapid accumulation of biliverdin. Male livers had a much higher fat content, but by the end of spawning even these livers had a reduced fat content. Initially the water content of male livers was much lower but by spawning time no real difference was found between male and female livers. No significant difference could be detected in the protein content of male and female livers.