Estimation of the relationship between size box categories and the mantle length composition of neon flying squid caught by Japanese squid jigging vessels

This study investigates the relationship between size-box categories and mantle length of the neon flying squid (Ommastrephes bartramii, NFS) caught by Japanese squid jigging vessels in the North Pacific Ocean. On-board size measurements of mantle lengths of squid caught by commercial jigging were conducted from May to July in 2012 and 2013, covering eight size-box categories. In total, the mantle lengths of 3451 individuals were measured. Squid sorted into the 6-10, 11-15, and 16-20 size-box categories were mostly in the mantle length class of 35 cm or larger, whereas those in the 41-50 and 51-60 size box categories were in the mantle length class of 20 cm or smaller. These mantle length frequency distributions were fitted with a lognormal distribution. The mantle length compositions obtained in this paper could be used to estimate length distributions of NFS landings under condition of number of boxes by size-box category available.