Male crabs smaller than 40 mm have steadily declined since 1996, which suggests a series of weak year classes that are expected to provide poor recruitment to the fishery beyond 2001. The biomass of mature females has declined since 1995. Poor prospects for recruitment, resulting from declines in abundance of mature females and smaller mature males, are not related to the fishery. The causes of decline for this portion of the population include bitter crab disease, environmental warming, and cannibalism. Bitter crab disease is 100 per cent fatal to crabs within a year of acquiring the disease.
Young crab are particularly susceptible.
Snow crab prefer cold water conditions. Larger areas of cold water may have assisted in the unprecedented growth of crab stocks over the past several years. Likewise, more recent bottom water warming may be negatively impacting the crab stock. Crab Biology A fully-grown male crab is approximately twice as large as most mature females, reaching a maximum shell width of 140 mm. Mating is thought to occur mostly in the spring.