Plasma cortisol level for stress measurement of Japanese whiting Sillago japonica captured by sweeping trammel net

To investigate the stress response of Japanese whiting Sillago japonica ass ociated with the capture process of sweeping trammel net, plasma cortisol l evels of the fish were measured as a stress index. The result revealed that the plasma cortisol levels increased from just after capture to 24 hours, then tended to decrease in 72 hours by keeping them in a tank. In the gille d capture, changes in cortisol level were relatively similar, while for the pocketed capture, it decreased after 24 hours. Changes in plasma cortisol of mesh-cut released samples for gilled capture were relatively similar to the usual gilled capture. Hook and line stress, however, did not show any f luctuation compared to the sweeping trammel net capture, Tight contact with the mesh twine for the gilled fish during the capture process was consider ed to cause the higher stress of fish.