A Critical Look at the Idea of Terminal Molt in Male Snow Crab ( Chionoecetes opilio )

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Dawe, Earl G., Taylor, David M., Hoenig, John M., Warren, William G., Ennis, Gerald P., Hooper, Robert G., Donaldson, William E., Paul, A. J., Paul, Judy M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1991
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; The ''Y''; Chionoecetes opilio; Snow crab
• Online Access: http://dx.doi.org/10.1139/f91-266; http://www.nrcresearchpress.com/doi/pdf/10.1139/f91-266

Whether or not male snow crab (Chionoecetes opilio) undergo a terminal molt when they develop large chelae is reviewed. Evidence supporting terminal molt includes laboratory studies in which large-clawed animals failed to molt and field studies which failed to find large-clawed males with mouth parts indicating imminent molting. Both studies were poorly documented. The field studies were largely conducted during inappropriate seasons and molt status based on a questionable mouth part stage. There is also an unsubstantiated claim that large-clawed animals fail to form limb buds for limb regeneration during the next molt and an inconclusive study of the degeneration of the Y-organ. We present new data against terminal molt including capture of large-clawed males with internal carapaces indicating impending molts, capture of two large-clawed animals with mouth parts indicating active premolting, recovery of two tagged large-clawed animals which molted while at liberty, and that the largest small-clawed animals usually are not large enough to account (through growth in a single molt) for the largest of the large-clawed animals. Also, one large-clawed male reportedly molted in captivity. We conclude that the existence of a terminal molt in male snow crab is not proven.