Abstract
The influence of size on the vulnerability of the snow crab ( Chionoecetes opilio O. Fabricius, 1780) to cannibalism was examined in the laboratory. Seventy four trials were conducted involving 2 male adult snow crabs >110 mm carapace width (CW) and 6 or 12 smaller snow crabs varying in mean size from 16 to 86 mm CW. Numbers of snow crabs cannibalized, having lost legs, injured or intact were noted. The crabs were either fed or not fed and the bottoms of the tanks were either covered or not covered with shells and pebbles. Cannibalism was strongly influenced by size of prey crabs. The number of crabs killed was high in the 30 and 37 mm CW size classes and declined in smaller and larger snow crabs. Proportion of crabs with missing legs increased below 58 mm CW and followed a similar pattern as the proportion of crabs cannibalized. The number of injuries increased markedly in crabs larger than 44 mm CW, peaked at 58 mm CW and declined in still larger crabs. Cannibalism was more frequent among unfed than among fed snow crabs. Fewer crabs were killed or lost one or more legs in tanks with shells and pebbles and a higher proportion had injuries or were intact in tanks with shells and pebbles. Our study suggests that cannibalism as a potential feedback mechanism controlling recruitment and involving large male adult snow crabs would act upon a very restricted size range of snow crabs.
Published Version
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