Meeting Abstract

P2.136  Saturday, Jan. 5  Temporal secretion of ecdysteroids over the premolt period in two life histories of Tanner crab Chionoecetes bairdi KELLER, EK*; TAMONE, SL; RAY, L; University of Alaska Southeast; University of Alaska Southeast; University of Alaska Southeast ekkeller@uas.alaska.edu

Chionoecetes bairdi (Tanner crab) and C. opilio (snow crab) are commercially important crabs that inhabit the North Pacific. Unlike many other crustaceans, C. bairdi and C. opilio undergo a terminal molt before becoming mature adults. Studies showed that C. bairdi and C. opilio males do not undergo their terminal molt at a particular size or developmental stage. Because Tanner crabs are harvested according to size, the fishery could be selecting for smaller sized crab at maturity. Understanding environmental or hormonal regulators of molting is important for understanding growth which is important for managing a sustainable fishery. Molting is coordinated by ecdysteroids (molting hormones) and methyl farnesoate which is similar to the developmental hormone in insects. It is likely that MF influences the terminal adult-differentiating molt. The objectives of this study were to determine the duration of pre-molt in C. bairdi and improve our understanding of how hormones influence the terminal molt. Hemolymph samples were collected from 47 adolescent male C. bairdi over a six month period until the crab molted. Most of the crab terminally molted during the sample period, but some also molted to larger adolescents. Hemolymph ecdysteroids were analyzed using an ELISA. Ecdysteroids at the onset of pre-molt were 357.1 ±67.5 ng/ml. Ecdysteroids peaked at 2056.5 ±435.2 ng/ml, then dropped to 79.6 ±96.0 ng/ml during molt and remained low (<20 ng/ml) post-molt. C. bairdi spend approximately 120 days in pre-molt and this is independent of crabs undergoing a terminal molt.