Survival of Japanese whiting Sillago japonica and by-catch species captured by a sweeping trammel net

SUMMARY: The survival of Japanese whiting Sillago japonica and by-catch species captured by a sweeping trammel net was examined to assess the effects of differing species, captured conditions, and body lengths on survival, in Tateyama Bay, Chiba Prefecture, Japan. All the live samples were kept in laboratory tanks for 4 days of successive survival observation. The survival ratio of the Japanese whiting varied by the captured conditions. The fish captured by pocketed condition was 27% surviving at the fourth day, which was significantly higher than the gilled and entangled fish. Most of the by-catch species survived for 4 days. About 60% of dead Japanese whiting were observed to have scar injury and damage on the body surface. For the by-catch species, the body damage occurred only in stripedfin goatfish Upeneus bensasi, Temminck's surfperch Ditrema temmincki, and tidepool gunnel Pholis nebulosa. Therefore, it suggests that the conservation measure through catch-and-release may be an appropriate method for most by-catch species, but not for the Japanese whiting.