Tajima Fisheries Technology Institute, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries, Kami, Hyogo 669-6541, Japan
To maintain the freshness of fish caught by offshore trawl fisheries in the western part of the Sea of Japan, reasonable methods of onboard refrigeration were investigated. The temperature of the abdominal cavity of the fish just after capture in the high seawater temperature fishing season (Sep. - Oct.) was found to have risen to nearly the surface seawater temperature. By packing and storing in ice the fish caught by offshore trawl fisheries in a fish box (20-kg box) without preparatory chilling, it took 10 hours or more to effectively refrigerate all of the fish in the fish box. Among the refrigerating methods (air cooling, water cooling, ice storage), the water cooling method was found to be the most effective for quick cooling of fish. This study clarified the conditions of cooling the fish of different species, sizes and temperatures of the abdominal cavity just caught by offshore trawl fisheries in refrigerated seawater. Cooling the fish in refrigerated seawater before packing them in the fish box for ice storage was found to be effective for preserving their freshness.