The feasibility of escape mechanisms in conical snow crab traps

Winger, P. D., and Walsh, P. J. 2007. The feasibility of escape mechanisms in conical snow crab traps. - ICES Journal of Marine Science, 64: 1587-1591.Laboratory observations and morphometric measurements of snow crab (Chionoecetes opilio) were conducted to examine the feasibility of incorporating rigid escape mechanisms into conical snow crab traps to improve trap selectivity. Under laboratory conditions, undersized adolescent male snow crab (≤94 mm carapace width) were capable of detecting, approaching, and interacting with escape mechanisms, and the location of the mechanisms was important in determining the likelihood of escape success. Escape mechanisms mounted low on the exterior wall of the trap received more than three times the number of penetration attempts than those mounted higher, although successful escape rates were very low. There was no difference in behaviour or escape success between traditional mesh traps and experimental wire (Aquamesh ® ) traps fitted with escape mechanisms. Morphometric measurements suggest that an escape diameter of 95 mm would optimize the egress of small crab and prevent the loss of legal-sized crab.