Seasonal changes in swimming behavior of adult Japanese flounder Paralichthys olivaceus in the coastal waters off Nagasaki Prefecture, Japan

¹Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, ²Seikai National Fisheries Research Institute, Fisheries Research Agency, Taira-machi, Nagasaki 851-2213, ³Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, ⁴Institute for East China Sea Research, Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Taira-machi, Nagasaki 851-2213, ⁵Touhoku National Fisheries Research Institute, Fisheries Research Agency, Shiogama, Miyagi 985-001, Japan

 To clarify the seasonal changes in swimming behavior of adult Japanese flounder Paralichthys olivaceus, we used depth-temperature data loggers to monitor the behavior of the fish in the East China Sea (ECS) and Omura Bay (OMB), Nagasaki Prefecture, Japan. We obtained behavioral data from December to the following May. In the OMB, the activity rate of the fish in December was 0.2% but in April the activity rate increased to 2.6%. Similar results were obtained in the ECS. However, the activity rate in January in the ECS was 38.8 times greater than that in the OMB. Our results suggest that such spatio-temporal variations in swimming behavior of the flounder affect the catchability of fixed fishing gear for the flounder, such as gillnets, deployed in the study region.