Reproductive cycle of the dungeness crab, Cancer magister, in Southeastern Alaska

Abstract

This study examined if female Dungeness crabs in Alaska reproduce annually. Crabs (287) were reared in flow-through tanks for one year and gonadosomatic indexes (GSI) and oocyte areas were calculated for seven months. Non-reproducing females had higher GSI and oocyte areas than reproducing females (<0.0001); resorption of gonads was observed. Male GSI varied significantly over the year. Crabs (27,506) were sampled with commercial pots and scuba in April and September in Glacier Bay, Alaska from 1992 to 1998. A large percentage (86%) of non-ovigerous females were observed in the spring when females should be brooding eggs. Molting probability is reduced as females become larger and they rely on stored sperm to fertilize eggs. A tagging study confirmed some females skip at least one mating season and extrude eggs in another season without ecdysis. This study demonstrated not all mature female Dungeness crabs in Alaska, especially larger females, reproduce annually.