• Title, Summary, Keyword: 트롤조업

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Fish Stock Assessment by Hydroacoustic Methods and its Applications - I - Estimation of Fish School Target Strength - (음향에 의한 어족생물의 자원조사 연구 - I - 어군반사강도의 추정 -)

  • Lee, Dae-Jae;Shin, Hyeong-Il;Shin, Hyong-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.2
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    • pp.142-152
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    • 1995
  • The combined bottom trawl and hydroacoustic survey was conducted by using the training ship Oshoro Maru belong to Hokkaido University in November 1989-1992 and the training ship Nagasaki Maru belong to Nagasaki University in April 1994 in the East China Sea, respectively. The aim of the investigations was to collect the target strength data of fish school in relation to the biomass estimation of fish in the survey area. The hydroacoustic survey was performed by using the scientific echo sounder system operating at three frequencies of 25, 50 and 100kHz with a microcomputer-based echo integrator. Fish samples were collected by bottom trawling and during the trawl surveys, the openings of otter board and net mouth were measured. The target strength of fish school was estimated from the relationship between the volume back scattering strength for the depth strata of bottom trawling and the weight per unit volume of trawl catches. A portion of the trawl catches preserved in frozon condition on board, the target strength measurements for the defrosted samples of ten species were conducted in the laboratory tank, and the relationship between target strength and fish weight was examined. In order to investigate the effect of swimbladder on target strength, the volume of the swimbladder of white croaker, Argyrosomus argentatus, sampled by bottom trawling was measured by directly removing the gas in the swimbladder with a syringe on board. The results obtained can be summarized as follows: 1.The relationship between the mean volume back scattering strength (, dB) for the depth strata of trawl hauls and the weight(C, $kg/\textrm{m}^3$) per unit volume of trawl catches were expressed by the following equations : 25kHz : = - 29.8+10Log(C) 50kHz : = - 32.4+10Log(C) 100kHz : = - 31.7+10Log(C) The mean target strength estimates for three frequencies of 25, 50 and 100 kHz derived from these equations were -29.8dB/kg, -32.4dB/kg and -31.7dB/kg, respectively. 2. The relationship between target strength and body weight for the fish samples of ten species collected by trawl surveys were expressed by the following equations : 25kHz : TS = - 34.0+10Log($W^{\frac{2}{3}}$) 100kHz : TS = - 37.8+10Log($W^{\frac{2}{3}}$) The mean target strength estimates for two frequencies of 25 and 100 kHz derived from these equations were -34.0dB/kg, -37.8dB/kg, respectively. 3. The representative target strength values for demersal fish populations of the East China Sea at two frequencies of 25 and 100 kHz were estimated to be -31.4dB/kg, -33.8dB/kg, respectively. 4. The ratio of the equivalent radius of swimbladder to body length of white croaker was 0.089 and the volume of swimbladder was estimated to be approximately 10% of total body volume.

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On the Motion Characteristics of Small Trawler under Operation (소형 트롤 어선의 예망중 동요특성)

  • Lee, Chun-Ki;Kang, Il-Kwon;Kim, Jeong-Chang
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.1
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    • pp.65-72
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    • 2004
  • This paper deals with an experimental study on the dynamical characteristics of ship motion during trawling job on the real sea. The experiments were carried out on the small stern trawler, and roll and pitch motion of the ship according to the wave directions were simultaneously recorded by P/C in the same sea conditions. From these data, the statistical properties and power spectra were obtained, and then the analysis of ship motion in trwal job was made. As a result, it was found that the pitch motions in trwal job were displayed low amplitudes on the whole, but the rolling motions were displayed high amplitudes relatively, and very high value on the beam and quartering sea especially. Also, the trial ship has a high extinction coefficient in the roll motion, compared with the rule of stability, but when wave height takes 2.5m over, it can induce the safety of ship to scare occasionally. Therefore, a usefull countermeasure for the safety of ship has to be made adequately.

동해의 어업기술 개발 -왕돌초를 중심으로-

  • 박성욱;이정우;전영열;박차수
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • pp.37-38
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    • 2002
  • 경상북도 울진군 후포리에서 동쪽으로 13마일 떨어져 있는 왕돌초 주변해역은 한ㆍ난류가 교차하는 조경어장이면서 수중암초가 융기되어 있는 용승어장으로서 수산생물이 풍부한 반면 해황이 거친 특성을 갖고 있다. 따라서 왕돌초와 인접해 있는 어업인들은 수 십년전부터 5톤급이상의 어선 150여 척을 이용하여 채낚기, 자망, 통발, 저인망, 트롤 등으로 조업을 해 오고 있다. (중략)

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Catch Characteristics of Trawl Fisheries in the Indonesian Waters (인도네시아 수역 트롤어업의 어획특성)

  • 김형석;김광홍;정순범
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.37 no.4
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    • pp.251-256
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    • 2001
  • Catch characteristics according to the tide and fishing time were analyzed through the fishing log data of trawls which work at Arafura Sea of Indonesia. This study aimed to provide basic data to make a fishing plan from the catch difference according to fishing time after analyzing the suitable fishing time of fish species. The results obtained are summarized as follows ; 1. Catches were the largest at the day of very weak tide as 22.8% of total catch and was the smallest at the day of a little strong tide as 16.9% of total catch. 2 Catches of croaker Argyrosomus sp. & Johnius vogleri, silver hairtail Trichiurus lepturs and coachwhip ray Himantura sp. were the largest at the day of weak tide(20.8%), very weak tide(33.8%), a little strong tide(22.0%) and catch for croaker and silver hairtail were the smallest at the day of a little strong tide(18.7%-10.0%) and coachwhip ray was the smallest at the day of strong tide(16.8%). 3. Catches were the largest at the time of 08:00-12:00 as 19.7% of the total catch and were the smallest at the time of 20:00-24:00 as 14.1% of total catch. 4. Catches of croaker, silver hairtail and coachwhip ray were the largest at the time of 00:00- 04:00(21.0%), 08:00-12:00(35.0%) and 12:00-16:00 (21.2%) and were the smallest at the time of 12:00-16:00(12.7%), 20:00- 24:00(4.6%) and 20:00-24:00(13.4%).

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Possibility of Fishery in Offshore Wind Farms (해상풍력발전단지 내 어업 가능성에 관한 고찰)

  • Jung, Cho-Young;Hwang, Bo-Kyu;Kim, Sung-Cheol
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.5
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    • pp.535-541
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    • 2019
  • The purpose of this study was to investigate the possibility of fishery in offshore wind farms and evaluate the risk linked to the presence of turbines and submarine cables in these areas. With this objective, we studied an offshore wind farm in the Southwest Sea and the current state of vessels in the surrounding National Fishing Port. The risk assessment criteria for 22 fishing gears and methods were set by referring to the fishing boats; thereafter, the risk was assessed by experts. The fishing gears and methods that could be safely operated (i.e., associated with low risk) in the offshore wind farm were: single-line fishing, jigging, and the anchovy lift net. The risk was normal so that it is possible to operate, but the fishing gears and methods that need attention are: the set long line, drifting long line, troll line, squid rip hook, octopus pot, webfoot octopus pot, coastal fish pot, stow net on stake, winged stow net, stationary gill net, and drift gill net. Moreover, the fishing gears and methods difficult to operate in the of shore wind farm (i.e., associated with high risk) were: the dredge, beam trawl, and purse seine. Finally, those associated with very high risk and that should not be allowed in offshore wind farms were: the stow net, anchovy drag net, otter trawl, Danish seine, and bottom pair trawl.

A study on the survival rate of escaped fish from trawl codend -Comparison of survival rate for fish species- (끌그물에서 탈출한 어류의 생존율에 관한 연구 - 어종별 생존율 비교 -)

  • 양용수;안희춘;박창두;조삼공;정의철;백철인
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • pp.81-82
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    • 2001
  • 최근 세계는 각종 어로기기 및 어구어법 기술의 발달로 인한 자원남획에 대한 우려로 자원관리형 어업에 대해 새로운 인식을 하게 되었고, 남획문제를 해결하기 위한 다각도의 노력을 기울이고 있다. 그러나 우리 나라 연근해에서 조업하고 있는 대표적인 어업인 트롤어업은 타 어구에 비하여 어획성능이 매우 우수하여 자원남획의 소지가 많고, 다이아몬드형 망지의 구조적 특성으로 인해 소형어류의 탈출이 어렵고, 탈출한 어류도 탈출시의 어체손상으로 생존율이 극히 저조할 것으로 추정되어 자원관리의 주 대상 어업으로 등장하고 있는 실정이다. (중략)

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어류 체장의 자동 식별을 위한 어종별, 체장별 및 주파수별 음향 반사 강도의 데이터 뱅크 구축 -I - 75 kHz에 대한 음향 반사 강도의 체장 의존성 -

  • 이대재;신형일;김천덕;김무준;강희영;이유원
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • pp.55-56
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    • 2003
  • 현재, 국립수산과학원은 매년 한반도 주변수역, 인도양, 북태평양 및 기타 해역에 대한 어업자원조사를 실시하고 있는 데, 이 조사에서는 split beam 방식 계량어군탐지기에 의한 음향학적 조사와 중층트롤에 의한 시험조업 등이 병행되고 있다. 그러나, 대상 어류의 체장 추정을 위한 연구는 아직까지 수행되고 있지 않고 있는 바, TAC제도를 시행하고 있는 우리나라로서는 한반도 주변 수역에 서식하는 어종별, 체장별, 사용 주파수별 어류의 체장추정에 필요한 음향반사강도의 data bank를 구축하는 것이 시급한 선결과제가 되고 있다. (중략)

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Analyses of the submarine cable faults of EAC and Protection Ways (동아시아횡단 해저케이블 고장분석을 통한 보호방안)

  • Yoo, Jae-Duck;Shin, Hyun-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.5 no.3
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    • pp.227-232
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    • 2010
  • Submarine cable system has been affected by humankind activities like trawl and stow net which has been threatening submarine cable in Korea. This research presents the protection ways of submarine cable through the analyses of cable faults on EAC system for 8 years.

On the motion characteristics of small trawler in trawling job and sailing (소형 트롤 어선의 예망과 항해중의 동요특성)

  • Kang, Il-Kwon;Kim, Hyung-Seok;Kim, Jung-Chang;Kim, Min-Seok;Jo, Hyo-Jae;Lee, Chun-Ki
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.4
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    • pp.311-318
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    • 2004
  • It is very important for the safe navigation and fishing operation to ensure the hull response of a fishing vessel in rough seas. This is an experimental study on the dynamical characteristics of ship's motion during operating job and sailing in the real sea. The experiments were carried out on the small stern trawler in operating job and sailing, and then the ship's roll and pitch motion were simultaneously recorded by P/C according to the wave directions. From these data, the statistical properties and power spectra were obtained and the analysis of ship's motions in the both case were made. The results obtained are summarized follows : (1) The amplitudes of pitch motion don't appear a big different between trawl job and sailing, but at bow seas, its in sailing have a tendency to increase more than in trawl job. The amplitudes of roll motion appear a bog different between trawl job and sailing, but at beam sea, that slightly decreasing tendency. (2) The peak period of pitch motion in trawl job and sailing change, but that of roll motion don't change according to the direction of waves. (3) The warp tention cause the motion of hull to be reduce, if the tention of each side have a ballance.

Studies on the Distribution of Fisheries Resources by Bottom Trawling in the Yellow Sea (트롤조사에 의한 황해 주요 어족생물의 분포특성에 관한 연구)

  • 신형호;황두진;김용주
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.38 no.2
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    • pp.129-139
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    • 2002
  • Fish distribution characteristics are essential to assess and estimate fisheries resources in a particular area. The primary goal of this study is to determine the distribution characteristics by the bottom trawling in the Yellow Sea west of South Korea. The surveys were carried out between 33$^{\circ}$00'N~37$^{\circ}$00'N latitude and 124$^{\circ}$00'E~126$^{\circ}$00'E longitude at EEZ(Exclusive Economic Zone) of Korea in Yellow Sea on May and August, 1999 and April, 2000. The ships used in this survey were the R/V Chung-kyeong(G/T 300) and R/V Dong-baek(G/T 1,050) of Yeosu National University. The results obtained can be summarized as follows 1. From the trawl data the fisheries resources are seriously decreasing through most of the species(about more 50%) have been appeared only one time at the bottom trawl on April, 2000. The total fish species caught by the trawl net during the 3 times survey were 106 species and a few species(dominant species) of these occupied 50~90% of the quantity of the total quantity by number or by weight. Among the dominant species the tanaka's snailfish was recorded to be the most dominant species in the survey area. The fish species in the Yellow Sea were clustered according to the regions. They clustered in two or three partes to the south-north direction in the spring season and clustered in two parts to the on-off shore direction of the shore in the summer season. Most of the fish caught at the the trawl net with cover-net(30.3mm) were small sized. They were shorter than 15 cm in length and the extruding rate of the cod-end which was 60mm mesh size ranges about 90%. 2. The densities of the number and weight per unit volume derived from the total catches sampled in April, 2000 survey were $1532.2{\times}10^{-6}fish/m^3$ and $39.55{\times}10^{-6}kg/m^3$, respectively. 3. The density variation of fish population between 1999 and 2000 showed a slight tendency to increase.