Behavioural responses of red king crab to crab pots |
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| Authors: | Shijie Zhou Thomas C Shirley |
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| Institution: | Juneau Center, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 11120 Glacier Highway, Juneau, AK 99801, USA |
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| Abstract: | High bycatch of female and sublegal sized male king crabs in the fishery is of concern to fishermen and management agencies; the efficiency of gear currently used in the fishery needs to be improved. This study examined behavioural responses of red king crabs to pots under laboratory conditions with time-lapse video. Crabs approached the pot from downstream, 82% of searches were confined to within 135 ° of the downstream direction, and 78.3% of crabs searched less than 90 ° before leaving or entering. The probability of entry success increased with the number of approaches. Crabs which failed to enter made an average of 2.6 approaches compared with 3.9 approaches for crabs which entered pots. The entry success rate was 8.1%. No significant differences in approach, search, and entry were found between ovigerous females, juvenile females, legal-sized males, and sublegal-sized males. Legal males (≥ 178 mm carapace width) had a significantly lower escape attempt rate and escape rate than sublegal males and females. Crabs depend on chemical cues during foraging, approaching, and searching. The current king crab pot is inefficient because crabs have difficulties in accessing the entrances and non-legal crabs have difficulties in escaping. |
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| Keywords: | Red king crab Behaviour Pots |
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