Hemolymph molting hormone concentrations in red king crabs from the Barents Sea

Recent declines in red king crab (Paralithodes camtschaticus) stocks in its native and introduced habitat have sparked interest in the development of aquaculture methods for this commercially important species. Little is known about the basic biology of this species and the factors controlling its growth rate. In this paper we present concentrations of circulating ecdysteroids (the hormones that control molting) in hemolymph of intermolt red king crabs in three coastal areas of the Barents Sea. Two molting hormones (20-hydroxyecdysone and ecdysone) were assayed. Mean levels of these ecdysteroids varied from 0.0 to 190.0 mu g ml(-1) and from 0.0 to 13.4 mu g ml(-1), respectively. These levels in general were higher in comparison with other decapod species. Concentrations of ecdysteroids were similar in male and female crabs and in injured (animals with at least one autotomized limb) and intact red king crabs. In contrast, the levels of circulating ecdysteroids were much higher in small (predominantly immature crabs) than in large adult animals because the latter have a lower molting probability (once per year) than smaller crabs (2-3 times per year). Our data can be used in further investigations of red king crab growth rates and their application to the development of aquaculture methods for this species.