1Marine Fisheries Research and Development Center (JAMARC), Fisheries Research Agency (FRA), Yokohama, Kanagawa 220-6115, 2Graduate Course of Applied Marine Bioscience, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 3Department of Marine Biosciences, Graduates School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 4Department of Ocean Science, Graduates School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
In the jigging fishery for neon flying squid Ommastrephes bartramii, the catch loss due to hooked squid falling off caused by tentacle breakage should be reduced. For this purpose, the jig motion was monitored with an acceleration data logger to examine the upward jig speed for the squid to be hooked by tentacles or other arms. Only the ratio of hooked tentacles increased when the upward jig speed was faster than 1.75 m/s, which caused tentacle breakage for smaller squid (mantle length: ML <35 cm). Through experimental fishing operation with different hauling speeds of the jig line drum, we concluded that the CPUE (number of squid caught/hour/jigging machine) can be maximized by controlling the upward jig speed at around 2.0 m/s for squid larger than 35 cm in ML, and at around 1.5 m/s for smaller squid, to reduce falling-off caused by tentacle breakage.