Study site: Iwate, Japan

Target species: Ocean sunfish (Mola mola)

    Ocean sunfish are the heaviest teleost in the world. They were thought as planktonic fish and believed to mainly feed on jellyfish, but recent studies have revealed active aspect of them. In Iwate, a lot of large and small sunfish are caught by set-net in early summer. I tried to deploy data-loggers on large sunfish to get information about feeding and behavioural thermoregulation of them. I succeeded to get behavioural data from 3 sunfish.

    This study was helped by set-net fishermen belong to Funakoshi Bay Fishery Cooperative Association.

The sunfish were raised on the fishermen’s boat, and released near the set-net after immediate tagging.

A blue shark (Prionace glauca) swam across of the tagged sunfish.