Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium—The Balance between Production and Environment

Stress Response of Crested Flounder Pleuronectes schrenki Captured by Set Net

Takafumi Arimoto, Atsuhiro Tsunoda, Seiji Akiyama, Nobuharu Fujimoto, Ari Purbayanto


Improving fishing technology has long been a goal of fishing technologists. Current pressure to change from catching more fish to catching fish at a sustainable level is increasing.

The survival of fish after encountering gear is the goal of improving the capture process to minimize the waste among escaped and released bycatch after onboard sorting (Chopin and Arimoto 1995; Chopin et al. 1995, 1996a, 1997). The eco-friendly level of each fishing gear can be evaluated by measuring the stress and survival of fish. Until now, such evaluations have been carried out for trawl net (Soldal et al. 1993; Suuronen et al. 1996), gillnet, and angling gear (Chopin et al. 1996b) but not for set net gear.

The set net is a passive type of gear used to fish coastal waters. The leader net blocks the fish school approaching the coast and guides them to the main net entrance, set in deeper water. The fish school inside the court passes into the final trap through the slope net or funnel net (non-return devices) and is harvested by hauling the net in the final area once or twice a day. The selective function of this gear greatly depends on the voluntary behavior of fish against it. In general, various species and sizes can become entrapped in this type of gear. Therefore, improving the selectivity (for size and species) of the final trap and sparing unwanted fish would be beneficial to both fishers and stocks.

In this paper, the stress response of cresthead flounder Pleuronectes schrenki captured by set net is examined through analysis of plasma cortisol levels to identify the peak stress levels after capture as well as in the recovery phase by keeping the fish in a tank for up to 35 d.