1National Research Institute of Fisheries Engineering, Hasaki, Ibaraki 314-0421, 2Shimonoseki Research Institute, Nichimo Co., Ltd., Shimonoseki, Yamaguchi 750-1136, 3Aichi Fisheries Research Institute, Minami-Chita, Aichi 470-3412, Japan
We investigated designs of an otter board and two trawl nets, designed to target different species, one for mantis shrimp and one for sea bass, used in Ise-wan Bay, Aichi, Japan. Rectangular nettings of retail products were used to construct two trawl nets to simplify manufacture and repair, and not to leave netting scraps. Results from experimental tows showed that the net heights and gear drag forces for a net for mantis shrimp and a net for sea bass were 1.47-1.79 m and 11.47-16.74 kN, and 1.61-1.84 m and 11.56-16.10 kN respectively. The net heights of both trawl nets were not much different although a design of trawl net for sea bass aimed to keep higher mouth opening. Measured maximum drag force (16.74 kN) was considered to reflect maximum towing ability of a fishing boat since maximum drag forces measured with two different trawl net designs were almost equal.