• 제목/요약/키워드: overfishing

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쉐퍼모형 응용을 통한 어로활동수준 검정 (Test of Fishing Activity Levels using Schaefer Model)

  • 이광남
    • Ocean and Polar Research
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    • 제31권2호
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    • pp.157-165
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    • 2009
  • The study examined overuse of the fishery resource. Influence of fishing activity was estimated by application of Schaefer model's. Fishing efforts that produced the maximum sustainable yield were determined in the model, allowing the effect of overfishing to be assessed. In the model, a wide variety of fish species as well as crustaceans and shellfish were susceptible to overfishing, while mollusks were not. Overfishing by modern techniques exacted a greater toll than more traditional methods. The results of the modeling study suggest that the 'Buy bag' input-control system of fisheries resource management warrants consideration, as does modernization, expansion and strengthening of self-control management of the fishery resource. Finally, more effective efforts in dissemination of policy information and education concerning the fishery resource are needed.

해양낚시의 자원 및 생태환경적 문제와 제도적 관리의 필요성 (A Resource, Ecological and Environmental Problems of Marine Recreational Fisheries and the Need for Institutional Management)

  • 이상고;박정석
    • 수산해양교육연구
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    • 제15권1호
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    • pp.25-46
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    • 2003
  • Marine recreational fishing is one of the most popular outdoor leisures and the number of people who are participating is sharply increasing more and more because of the increasement of their income and demand for marine leisure. However our ecosystem is inevitably facing marine environmental deterioration and overfishing. That is because marine recreational fisheries resources are common property resources which can be catched by anyone not willing to pay for them except their private costs as commercial fisheries. Also fisheries resources unlike other resources are renewable resources and have a critical zone. That is, having a possibility of severe depletion may result from high discount rates used by private exploiters. This paper is focused on that marine recreational fishing license system which is adopted in most advanced countries such as Canada and U.S. and included in deterioration. And money obtained by license fee should be spent for more improvement fishing culture and welfare for marine recreational fishers.This system can lower the high rates of discount and be useful to become a sustainable marine recreational fishing industry.

평가자료가 결핍된 어업의 과도어획상태와 자원의 남획여부를 결정하는 실용적인 방법 (A Pragmatic Approach for Determining Overfishing and Overfished Condition for Assessing Data-deficient Fisheries)

  • 장창익;이재민
    • 수산해양교육연구
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    • 제25권5호
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    • pp.1009-1019
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    • 2013
  • 본 연구는 어업자원이 건강한 상태에 있는지 아니면 남획된 상태에 있는지를 판단하고, 현재 어업활동이 과도한지 아닌지를 판단하기 위한 간단하고 실용적인 방법을 개발하였다. 자원평가를 수행시에는 고가의 자료와 고도의 기술력이 요구되는 어려움이 있는데, 특히 소규모 어업과 다종어업에서 어려움이 더욱 심하다. 본 연구에서 개발된 방법은 어업자원의 구체적인 상태와 어업활동의 객관적인 상태를 고려해서 어업자원을 보존하고 어업활동을 규제할 수 있는 실용적이고 신뢰할 수 있는 방법이다. 예를 들어, 자원량과 어획사망률을 추정하는데 필요한 자료가 없거나, 추정할 수있는 과학적 능력이 부족한 경우에는, 자원량을 대용해서 단위노력당어획량을 사용하고 어획사망률을 대용해서 어획노력량 자료를 사용할 수 있다. 본 연구에서 제시한 방법의 실현가능성과 유용성을 입증하기 위하여, 복수어종으로 집계된 어획량과 어획노력량 만으로 된 경우나 또는 개체군 특성치 정보와 체장자료 만이 이용 가능한 경우에 대해 적용하였다. 이 방법은 수산자원의 보존이라는 전지구적 목표를 달성하는데 있어서, 필요한 자원상태와 어업상태를 판단해서 어획활동을 규제하고 조정할 수 있는 유용한 방법이 될 수 있을 것으로 보인다.

확률론적 연령구조모델을 이용한 한국 고등어(Scomber japonicus) 어획 강도 (Management Reference Points for Korea Chub Mackerel Scomber japonicus Stock)

  • 김진우;현상윤;이재봉
    • 한국수산과학회지
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    • 제53권6호
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    • pp.942-953
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    • 2020
  • Achieving optimal sustainable yields (i.e., avoiding overfishing and maximizing fishery harvest at the same time) is one of the main objectives in fisheries management. Generally, management reference points (MRPs) such as fishing mortalities (Fmsy, F0.1, Fx%) have been suggested for the purpose. In this study, we intended to suggest MRPs for Korea chub mackerel Scomber japonicus stock, using a stochastic catch-at-age model (SCAA) and evaluate whether the current fishing intensity on the stock is appropriate. We used length frequency and catch-per-unit-effort data on the Korea chub mackerel stock collected from the large purse-seine fishery, and yields landed by all fisheries from years 2000 - 2019. We calculated yield per recruit and spawning potential ratio, and projected spawning stock biomass (SSB) under different fishing mortality, assuming annual recruitments were solely controlled by environmental effects (i.e., steepness of 1.0). Some of our major findings and suggestions were that the overfishing threshold would be F46%; i.e., the fishing mortality in the terminal year, 2019 was 0.257/year, which corresponded to F46%.

Biological Characteristics of Skates(Elasmobranchii: Rajidae)

  • Nakabo, Tetsuji
    • 한국어업기술학회:학술대회논문집
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    • 한국어업기술학회 2000년도 춘계수산관련학회 공동학술대회발표요지집
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    • pp.463-464
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    • 2000
  • Skates are one of the most favorite food fishes for Korean people. It is, I think, important to know the biological characteristics of skates for protecting the fishes from the extinction caused by overfishing. Femily Rajidae encompasses about 200 species which is one fourth of elasmobranch fishes, and 11 species known from the Korean waters. But, very few biological characteristics of skates have been known Some of them are shown here and discussed comparing with those of other elasmobranch fishes (sharks and rays) and teleost fishes. (omitted)

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한·중 황해거버넌스에 관한 고찰 (A Consideration on Yellow Sea Governance of Korea and China)

  • 조동오;주현희
    • 해양환경안전학회지
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    • 제19권2호
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    • pp.186-192
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    • 2013
  • 황해(Yellow Sea)는 평균수심(44 m)이 낮고 한국과 중국연안에 넓은 갯벌이 있어서 1차 생산성(>300 $gC/m^2/year$)이 매우 높아 수산자원 등 해양생물자원이 풍부한 생태물리환경을 지니고 있다. 그러나 황해는 중국대륙과 한반도로 둘러싸인 반폐쇄해역(49만$km^2$)의 광역해양생태계로서 오염 및 남획 등에 의한 외부충격이 심할 경우 생태계의 균형이 파괴되고 회복이 불가능한 특성을 지니고 있다. 최근 한 중간 어업협정 이후 중국 어민의 남획 및 불법조업 그리고 한 중 연안의 과도한 개발로 인한 환경피해로 황해생태계에 심각한 충격이 가해지고 있다. 본 논문은 한 중 황해거버넌스의 주요 구성요소인 이해당사자, 법률 및 제도, 정부조직 및 정책을 고찰하고 한 중 황해국제협력인 황해광역생태계보전사업(YSLME), 북서태평양보전실천계획(NOWPAP), 한 중황해환경공동조사사업의 평가를 통해 황해의 이용 및 개발압력의 지속적 증가에 대처하는 통합적 거버넌스체계의 구축을 제안하고 있다.

한국 동해 생태계의 어획강도 변화에 따른 자원량 예측 연구 (A study on the forecasting biomass according to the changes in fishing intensity in the Korean waters of the East Sea)

  • 임정현;서영일;장창익
    • 수산해양기술연구
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    • 제54권3호
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    • pp.217-223
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    • 2018
  • Overfishing capacity has become a global issue due to over-exploitation of fisheries resources, which result from excessive fishing intensity since the 1980s. In the case of Korea, the fishing effort has been quantified and used as an quantified index of fishing intensity. Fisheries resources of coastal fisheries in the Korean waters of the East Sea tend to decrease productivity due to deterioration in the quality of ecosystem, which result from the excessive overfishing activities according to the development of fishing gear and engine performance of vessels. In order to manage sustainable and reasonable fisheries resources, it is important to understand the fluctuation of biomass and predict the future biomass. Therefore, in this study, we forecasted biomass in the Korean waters of the East Sea for the next two decades (2017~2036) according to the changes in fishing intensity using four fishing effort scenarios; $f_{current}$, $f_{PY}$, $0.5{\times}f_{current}$ and $1.5{\times}f_{current}$. For forecasting biomass in the Korean waters of the East Sea, parameters such as exploitable carrying capacity (ECC), intrinsic rate of natural increase (r) and catchability (q) estimated by maximum entropy (ME) model was utilized and logistic function was used. In addition, coefficient of variation (CV) by the Jackknife re-sampling method was used for estimation of coefficient of variation about exploitable carrying capacity ($CV_{ECC}$). As a result, future biomass can be fluctuated below the $B_{PY}$ level when the current level of fishing effort in 2016 maintains. The results of this study are expected to be utilized as useful data to suggest direction of establishment of fisheries resources management plan for sustainable use of fisheries resources in the future.

Stock assessment of elkhorn sculpin (Alcichthys alcicornis) along the Uljin area in the East Sea of Korea

  • Lee, Soo-Jeong;Zhang, Chang-Ik;Choi, Young-Min;Lee, Dong-Woo;Lee, Jae-Bong
    • 수산해양기술연구
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    • 제49권4호
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    • pp.432-439
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    • 2013
  • This study was performed to assess the current stock condition of elkhorn sculpin along the Uljin area in the East Sea of Korea. To assess the state of the stock, yield-per-recruit (YPR) and spawning biomass-perrecruit (SBPR) analyses were performed. Estimates of $F_{max}$ and $F_{0.1}$ were 2.10/year and 0.48/year, respectively, and those of $F_{35%}$ and $F_{40%}$ were 0.66/year and 0.54/year, respectively. Current fishing mortality was estimated at 0.63/year and the current age at first capture was 2.41years. $F_{40%}$ was set as the target reference point of the stock. SBPR at $F_{40%}$ and current SBPR were estimated to be 41.85g and 37.77g, respectively. Estimated FOTY which is the fishing mortality for the overfished threshold yield was 0.49/year. The ratio of SBPR/$SBPR_{MSY}$ was calculated as 0.90 and that of $F/F_{OTY}$ was 1.05. The ratio of $t_c/t_{c\;opt}$ was calculated as 1.15 and that of $F/F_{OTY}$ was 1.17. Therefore, the current stock condition of elkhorn sculpin along the Uljin area of Korea has not been overfished, however, it indicates that a light overfishing is going on this stock.

Stock assessment of the goldeyes rockfish Sebasetes thompsoni in the Ulleungdo area

  • HEO, Yo Won;LEE, Jae Bong;YANG, Jae Hyeong;LEE, Hae Won;CHA, Hyung Kee;ZHANG, Chang Ik
    • 수산해양기술연구
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    • 제53권1호
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    • pp.60-66
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    • 2017
  • This study researched the population of ecological characteristics of the goldeyes rockfish Sebasetes thompsoni sampled by gill net in the Ulleungdo area from February 2013 to February 2014 in order to assess the current stock status and provide scientific advice for management implementation. The instantaneous coefficient of total mortality (Z) was 0.78/year and the survival rate (S) was 0.459. The instantaneous coefficient of natural mortality (M) was 0.461/year. Based on the estimates of Z and M, the instantaneous coefficient of fishing mortality (F) was 0.318/year. The age at first capture ($t_c$) was 4.41/years. Current Yield-per-recruit (YPR) was 30.83 g, and fishing mortality at maximum YPR ($F_{max}$) and fishing mortality corresponding to 10% of the maximum slope in YPR curve ($F_{0.1}$) were 3.257/year and 0.673/year, respectively. $F_{35%}$ and $F_{40%}$, indicating fishing mortalities at 35% and 40% of maximum Spawning biomass-per-recruit (SBPR), were 0.619/year and 0.509/year, respectively. Based on the biological reference points, fishing mortality at overfished threshold yield ($F_{OTY}$) was calculated as 0.509/year. Current $SBPR/SBPR_{MSY}$ was 1.313 above 1.0, which means 'not overfishe,' while current $F/F_{OTY}$ was 0.629 below 1.0, which indicates 'not overfishing.' In conclusion, the current status of goldeyes rockfish was located in green zone (i.e., not overfished and not overfishing) according to the revised Kobe plot.