Characteristics of bycatch of Korean baited whelk pots for beni-zuwai crab, Chionoecetes japonicus, and some pot improvements to reduce the bycatch
2019
Yosho, I. (Japan Sea National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Niigata, Niigata (Japan)) | Hirose, T.
This paper examined improvements in the entrance of pots used in the Korean baited whelk pot fishery, in order to reduce bycatch of beni-zuwai crab Chionoecetes japonicus. Fishing experiments in fishing grounds were carried out using the original Korean whelk pots (square entrance of 30 cm in diagonal) and improved pots of two types (almost 15 or 10 cm), and the baited crab pots used in the Japanese beni-zuwai crab fisheries. The original pots caught both sexes but no immature females. Most males were smaller than 100 mm in carapace width (CW), and the ratio of immature males was higher than for the Japanese crab pots. The pots of 15 cm entrance effectively avoided catching larger male crabs (estimated size at 50% selectivity was 88.2 mm CW) without reducing the catch rate of whelks or adult female crabs. In the pots of 10 cm entrance, the selectivity of male crabs was 0.34 at most compared with the original pots; however, they failed to catch large whelk. The effect of pots of 10 cm entrance on the female crab catch remains unclear because few female crabs were caught in this study. Applications of these improvements to fisheries were discussed.
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