Ishikawa Prefecture Fisheries Research Center, Housu, Ishikawa 927-0435, Japan
The effectiveness of a light emitting diode (LED) fishing lamp consisting of 950 oval-shaped blue LEDs was investigated in offshore fishing grounds for the Japanese common squid Todarodes pacificus in the Sea of Japan. Squid jigging operations were conducted by R/V Hakusan-Maru (167 gross tonnes) equipped with 216 LED lamps and 78 metal halide (MH) lamps. Mean catch per unit effort was markedly lower in operations using only the 216 LED lamps (15 kW in total) but slightly lower in operations using both the 216 LED lamps and 24 MH lamps (87 kW in total) than using the 78 MH lamps (234 kW in total). The light from MH lamps widely spread in the sea surface layer but that from the LED lamps irradiated only a limited area near the vessel, suggesting that light distribution affected catch performance. Fuel consumption of the generator engine for lighting these lamps was proportional to the total electric power consumption of the lamps. Fuel consumption for lighting both the 216 LED lamps and 24 MH lamps was 37% of that for lighting the 78 MH lamps. These results indicate that fuel can be saved by the combined use of LED and MH lamps without a remarkable reduction of squid catch.