트롤 탈출어류의 생존율 연구

Abstract

The aim of this study was to develope a fishing technology for fisheries management for improving the survival rate of young fishes escaped from trawl net. Sea experiments were carried out to investigate the survival rate of the fishes in off Geomun island and Korean southern sea. Cover-net fish cage was designed and manufactured to collect fishes escaped from COD(codend) and TED(trawl escapement device). Fish cage was installed in a shallow site where scuba diver can observe the surviving fishes after separating the cage from trawl net. Most of fishes except horse mackerel(Trachurus japonicus) and mackerel(Scomber japonicus) could escaped through TED(bar space 35mm) easier than COD(mesh size 54mm). Especially, escapement rate of redlip croaker(Pseudosciaena polyactis) escaped from TED was the highest as 73.9%. Survival rate of horse mackerel(Trachurus japonicus) escaped from TED was 85.5% at the point of 96 hours over, while the survival rate for COD showed a rapid decrease according to the time elapse as 85.0% at the point of 24 hours, 76.4% for 48 hours, 62.7% for 72 hours and 56.1% for 96 hours. Over 90% of red seabream(Pagrus major) and rock bream(Oplegnathus fasciatus) escaped from TED were survived 96 hours over and the survival rate of those fishes were excellent compared with the other fish species. All korean pomfret(Pampus echinogaster) escaped from both COD and TED were died within 48 hours. Most of redlip croaker(Pseudosciaena polyactis) were also died within 12 hours because of the weak physiological characteristics by water pressure change. Survival rate of fishes like as horse mackerel(Trachurus japonicus) having hard skin was high while it was low for the fishes like as squid(Todarodes pacificus) and hair-tail(Trichiurus lepturus) having soft skin. We could know that there were big differences in the survival rate offish species escaped from trawl net.