• Journal of Life Science
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• v.16 no.1
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• pp.88-94
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• 2006

The random amplified polymorphic DNA (RAPD) technique was investigated as a potential tool for the origin identification of olive flounder (Paralichthys olivaceus) and redlip croaker (Pseudosciaena polyactis). Olive flounder specimens were collected from North Korea and several locations of South Korea (Jumunjin, Tongyoung and Geoje). Fishes obtained from Tongyeong and Geoje were cultured products. Redlip croaker specimens were collected from South Korea and China. Consistent and distinct diagnostic bands were easily identified in the RAPD patterns of the olive flounder specimens. Although consistent diagnostic bands rarely appeared in the RAPD pattern of redlip croaker specimens because of their genetic heterogeneity, we were able to find potential diagnostic bands in the average RAPD pattern of each origin.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.384-390
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• 2016

The purpose of this paper is to improve the availability of underwater sound by the fundamental data on the hearing ability of Redlip croaker Pseudosciaena polyactis, which is cultured according to the cultivation technology, recently. The auditory thresholds of Redlip croaker were determined at 6 frequencies from 80Hz to 800Hz by heartbeat conditioning method using pure tones coupled with a delayed electric shock. The audible range of the Redlip croaker extended from 80Hz to 800Hz with the best sensitive frequency range including little difference in hearing ability from 80Hz to 500Hz. In addition, the auditory thresholds over 800Hz increased rapidly. The mean auditory thresholds of the Redlip croaker at the test frequencies from 80Hz to 800Hz were 90.7dB, 93.4dB, 92.9dB, 94.4dB, 95.5dB and 108dB, respectively. Auditory masking for the redlip croaker was measured using masking stimuli with the spectrum level range of about 66, 71, 75dB (0dB re $1{\mu}Pa/{\sqrt{Hz}}$). According to white noise level, the auditory thresholds increased as compared with thresholds in a quiet background noise. The Auditory masking by the white noise spectrum level was stared over about 70dB within 80~500Hz. Critical ratio ranged from minimum 20.7dB to maximum 25.5dB at test frequencies of 80Hz~500Hz.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.241-247
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• 2005

The aim of this study was to develop a trawl escapement device which can improve the survival rate of young fishes passed through trawl codend. The sea experiments according to the bar space of the device and bar materials were carried out to decide the bar space and device materials in Korean southern sea and off Cheju island. Stainless pipes and MC bars were used to test the efficiency of escapement device materials. Although escapement rates of MC bar for main species were a little higher compare with stainless pipe, the efficiency of device for stainless pipe was better than MC bar. Escapement devices of sort-K type and grid panel type were also compared. Escapement rates of redlip croaker(Pseudosciaena polyactis), blackthroat seaperch(Doederleinia berycoides) and finespotted flounder (Pleuronichthys cornutus) showed 61.7%, 2.0% and 2.7% on the sort-x type and 69.9%, 1.1% and 2.0% for the grid panel type but the difference was little. Fishes under 20mm head width and fishes which swimming speed is so slow compared with body length could not go through well the device. Escapement rates according to the bar space were estimated using grid panel type. The rates of redlip croaker(Pseudosciaena polyactis) for the bar space of 20mm, 25mm, 35mm were increased as 60.3%, 61.0% and 77.8%, and 9.8%, 16.4% and 45.6% for horse mackere1(Trachurus japonicus), respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.69-77
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• 2006

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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.87-91
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• 2003

Experimental fishing was carried out to investigate the survival rate of fishes discarded after hauling from the trawl and to develop the fishing gear and method for fisheries management which can improve the survival rate of young fishes escaped from the trawl codend in offshore korean southern sea and off Cheju Island of Korea. The young fishes were bred in fish cage on the board to measure the sustainable survival time for fishes escaped from grid panel and codend. The obtained results are summarized as follows' 1. Japanese flying squid(Todarodes pacjficus), mitra squid(Loligo chinesis), hair-tail( Trichiurus lepturus), john dory(Zeus japonicus), spanish mackerel(Scomberomorus niphonius), redlip croaker (Pseudosciaena polyactis) and blackthroat seaperch(Doederliinia berycoides) were dead instantly after hauling. 2. Survival rate of tiger shark(Galeocerdo cuvier), conger eel (Conger myriaster), red skate (Dasyatis akajei), black scraper(Navodon modestus) and japanese fan lobster(Ibacus ciliatus) might be high after discarding because they survived for long hours in fish cage. 3. Blotched eelpout(Zoarces gili) escaped from the escapement device(grid) was dead within 6 hours in the water tank installed on the board but 97% of tiger shark and 72% of conger eel survived over 72 hours. 4. Red skate escaped from trawl codend was dead within 60 hours in the water tank installed on the board but sustainable survival time of 25% of octopus(Paroctopus dofleini) and 100% of black scraper was over 72 hours. 5. Compared with the survival rate of rosefish(Helicolenus higendorfi) escaped from the escapement device(grid) and trawl codend, all of the rosefish escaped from the grid was dead within 7.2 hours but 8.3% of the rosefish escaped from the codend survived over 72 hours. 6. In comparison with the survival rate of japanese fan lobster survived over 72 hours, survival rate of japanese fan lobster escaped the codend was much higher as 75% than 33% of japanese fan lobster escaped from the grid.