Blue shark <i>Prionace glauca</i> is a large shark species distributed in tropical to temperate oceans around the world. Since blue sharks often swim in the surface layer, they are caught by driftnet fisheries. Research driftnet surveys with a series of driftnets of 13 different mesh sizes of 22-157 mmwere conducted in the Northwest Pacific Ocean during 1999-2013. From the data on precaudal length distribution of blue shark caught by each mesh size in these surveys, this study estimated the mesh selection curve of driftnets by using the SELECT method. AIC chose the log-normal selection curve model. Simultaneously, the precaudal length frequency distribution of the blue shark encountering the driftnets was also estimated. In this driftnet survey catch, the abundance of large-sized blue shark was underestimated because no driftnets of sufficiently large mesh size were used. For blue shark with the optimum precaudal length for a given mesh size, the girth at the posterior end of the mouth aperture was smaller than that at the mesh perimeter. Blue shark was most effectively retained by the entangling process in which the shark was snagged, rolled or entangled in the net after the snout entered the mesh.
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