Fat reserves and reproduction in the green turtle, Chelonia mydas

Abstract

Measurements were made of the fat and water content of standard cores of fat lining the inner carapace of green turtles caught and butchered by indigenous fishermen in Daru, Papua New Guinea. The amount of depot fat, total lipid and neutral lipid per core varied with the sex, maturity and reproductive status of the turtle. The fat content of cores from prepubescent turtles did not vary with sex. In contrast, cores from adult female turtles had a significantly greater fat content than those from males. Cores from pubescent and vitellogenic females had the highest fat content. Neutral (storage) lipid was significantly higher in cores from vitellogenic females than in those from breeding, which suggests that sub-carapace depot fat is used to fuel the energetically expensive costs of migration and egg production. Cores from breeding females had a significantly higher fat content than those from males, which suggests that the energetic costs of vitellogensis and egg-laying are reflected in sub-carapace fat stores. The greater energetic cost to this fat store for breeding by females is also reflected in the significantly higher water content of the fat of females that had bred in the previous season compared with those in vitellogenesis. In contrast, there was no significant difference between the water content of cores from non-breeding and breeding males.