Seasonal prevalence and intensity of Bitter Crab dinoflagellate infection and host mortality in Alaskan Tanner crabs Chionoeceles bairdi from Auke Bay, Alaska, USA

Since the 1984-1985 Tanner crab Chionoecetes bairdi season in southeastern Alaska, USA, an increasing number of crabs infected with a dinoflagellate parasite similar to Hernatodinium perezi have been identified in the commercial catches. This parasite causes a fatal d~sease known as Bitter Crab Disease (BCD) with peak mortality occurring dunng August and September. Average intensity and prevalence of this disease, as well as dinospore releases in Auke Bay Tanner crabs increased from May until August and September in both 1989 and 1990 falling again to zero by mid-winter. Prevalence of BCD infection and host mortality was not significantly different between years Knowledge of the seasonal prevalence and intensity of BCD parasitism and associated host mortality would assist management in conserving local Tanner crab stocks.