THOMTON, J.D.*; TAMONE, S.L.; ATKINSON, S. ; AK SeaLife Center, U. of AK Fairbanks; U. of AK Southeast; AK SeaLife Center, U. of AK Fairbanks: Hemolymph Ecdysteroid Concentrations in Wild and Captive Alaskan Dungeness Crabs

The currently accepted reproductive cycle of Alaskan female Dungeness crabs (Cancer magister) maintains that females molt and mate during summer months, extrude eggs in the fall, and incubate eggs for approximately 9 months through the winter until larval hatching in May/June. In this model, molting and mating are coincident with ovarian maturation. Recently, however it has been shown that a percentage of females skip the annual molt for at least one year and extrude viable eggs using sperm stored from a previous molt/mate event. Additionally, some crabs may molt and mate in the summer and delay extrusion until the following year. The goal of this study was to quantify hemolymph ecdysteroid (20-HE) concentrations using an enzyme-linked immunosorbent assay (ELISA), validated for the species, to assess the growth and reproductive status of wild and captive crabs. In wild crabs collected during May, June, and July 2004 (n=171) 100% exhibited intermolt 20-HE concentrations (<150 ng/ml), 80% displayed old, worn shells and only 65% had evidence of a previous clutch (blackened pleopods) since the last molt. Therefore, according to current theory a percentage of these crabs should molt and mate prior to fall egg extrusion, however, none of these females were in premolt. Additionally, female crabs sampled in May 2004 were retained and housed in aquaria to facilitate longitudinal hemolymph collection. Of these captive crabs, 43% exhibited a steady increase in 20-HE concentrations indicative of premolt (>150 ng/ml), with one crab molting during August. It is unclear at this time whether the increased elevation of 20-HE during late summer/fall will lead to delayed molt and egg extrusion or reproductive failure for one annual cycle.