The effects of windchill exposure on the snow crab, Chionoecetes opilio

Abstract

Millions of snow crabs, 'Chionoecetes opilio, ' are aerially exposed during sorting in the annual Bering Sea commercial fishery. A laboratory experiment measured snow crab responses to windchill exposure. Crabs were exposed to 8 to 16 m/s windspeed and air temperatures from -2 to -10 C̊ for 5 minutes. Mortality, autonomy, and righting response were assessed for seven days post-treatment. Crabs experienced 40% to 100% mortality at windchill from -10 to 16 C̊. Reduced exposure time significantly reduced mortality. Autonomy was variable but pronounced below -10 C̊ windchill. The righting response was impaired after all but the least severe treatment. Estimates of mortality of discarded snow crab in 1998 were calculated from deadloss of retained crab, a windchill model, and a temperature/windspeed model. No relationship existed between catch deadloss and the windchill conditions when the crabs were caught. Mortality of non-retained snow crab was estimated at 3.6% by the windchill model and 19.6% by the temperature /windspeed model.