Size selectivity of trap for male red queen crab Chionoecetes japonicus with the extended SELECT model

Abstract

A series of comparative fishing experiments was carried out in waters off the east coast of Korea in 1997, using traps of six different mesh sizes (95, 112, 122, 132, 152, and 172 mm mesh opening) to determine the size selectivity of a conical trap for male red queen crab, Chionoecetes japonicus. The extended SELECT (Share Each LEngth's Catch Total) analysis method was applied with fishing effort data to obtain trap size selectivity, with a symmetric logistic equation used to express selectivity curves. Traps of 95 mm mesh size were employed as the control gear in the analysis. Logistic and split parameters of each mesh-size trap in the SELECT model were calculated by the maximum likelihood method. The model of split parameter p fixed with equal fishing efficiency, was chosen from the likelihood ratio tests and Akaike's Information Criterion (AIC) comparison. From the determined logistic parameters, the carapace widths of 50% retention were estimated to be 82, 85, 92, and 101 mm for 122, 132, 152, and 172 mm mesh-size traps, respectively. The selectivity curves of each mesh-size trap showed that traps of larger mesh size allowed more crabs of small carapace width and low commercial value to escape.