相対エントロピーを用いたアーカイバルタグのデータ解析—希少種アカメの一例—

抄録

The Japanese giant perch (Lates japonicus) is one of the most mysterious fish in Japan. Its Japanese name “Akame” means red eye and the eye glows underwater exactly like a ruby. The fish mainly distribute along the Kochi and Miyazaki Prefecture coast and grow more than 130 cm over a period of 20 years. To monitor the behavior in the ocean, four adult Japanese giant perch were attached with archival tags and released along the Kochi coast. One individual was recaptured 696 days after release and its swimming depth, ambient water temperature, body temperature and light level were obtained every one minute. The trajectory from release to recapture was estimated using the light level. The fish was estimated to swim around the ocean. Vertical movements calculated from the swimming depth were analyzed using relative entropy techniques to detect the specific behavior. The relative entropy marked the maximum value on 22 June 2012 when the fish swam in deep and warm water considering the Kuroshio current. These results indicate that Japanese giant perch migrate between the Tosa and Satsunan area.