• 수산해양교육연구
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• 제15권1호
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• pp.81-100
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• 2003

It is undeniable that IUU Fishing are threatening so many legal fishermen' economic livelihood, negatively impact on conservation and protection of the fishery stock and ecosystem itself. Especially, negative impact of IUU Fishing resulted from the increasing fishery activities on the high seas. The Korea case of Coastal and Off-shore Fisheries, difficulties in conserving and controlling the fishery stock was brought about. Simultaneously, it is the fact that there are so many damage such as the reduction of fish Stock management program's effect, dissatisfaction of legal fishermen, over-exploiting of fish stock. Related with this kind of problem, FAO had adopted "International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing(2001)". From this reason, Korea also needs to make actual efforts to prevent IUU Fishing. i.e. each nation should develop Korea action plan by Feb. 2004 and impliment it, report on implementation toward FAO. This Paper will review the definition of the IUU stipulated by "International Plan of Action on Illegal, Unreported and Unregulated Fishing" and study Korea cases of the IUU fishing. Finally, the analysis of Korea's implementation will be done, centering around the contents stated on the International Action Plan. The significance of this paper is to grope the political countermeasures against international movement of the IUU fishing prevention.

• 수산해양기술연구
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• 제55권2호
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• pp.95-104
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• 2019

This study is aimed to take a stock assessment of blackthroat seaperch Doederleinia seaperch regarding the fishing effort of large-powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery. For the assessment, the state-space model was implemented and the standardized catch per unit effort (CPUE) of large powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery which is necessary for the model was estimated with generalized linear model (GLM). The model was adequate for stock assessment because its r-square value was 0.99 and root mean square error (RMSE) value was 0.003. According to the model with 95% confidence interval, maximum sustainable yield (MSY) of Blackthroat seaperch is from 2,634 to 6,765 ton and carrying capacity (K) is between 33,180 and 62,820. Also, the catchability coefficient (q) is between 2.14E-06 and 3.95E-06 and intrinsic growth rate (r) is between 0.31 and 0.72.

• Fisheries and Aquatic Sciences
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• 제26권10호
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• pp.617-627
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• 2023

Harvest control rules have been recently developed for some fisheries in Indonesia, including grouper fisheries, and are expected to reverse the trend of declining stocks. One of the proposed options of the harvest control rules is to implement the catch size limit. The catch size limit approach, however, is challenging, unless it is supported also with strong fisheries surveillance, law enforcement, and innovation. The catch size limit approach can be done by implementing changes in fishing methods and gear, including the application of different hook sizes in the hook and line fishing gear. This study examines the impact of different hook sizes on the length at first capture (Lc) and on the bell-shaped maximum selectivity using various selectivity models of the two targeted grouper species (Plectropomus leopardus and Plectropomus maculatus) in the Saleh bay, West Nusa Tenggara, Indonesia. We found that increasing hook size influences the grouper's catch size, increasing the Lc and the bell-shaped maximum selectivity of both species. Based on our findings, hook size can be used as one of the practical tools for grouper management measures, as part of harvest control rules to improve grouper stock in Indonesia.

• 수산해양기술연구
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• 제51권4호
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• pp.535-544
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• 2015

본 연구에서는 가입에 따른 산란자원량의 변화를 나타내어 가입남획을 방지하는 가입당 산란자원량 모델(spawning biomass per recruit model)을 비교 분석하였다. 가입당 산란자원량 모델은 연령별 선택비를 고려하지 않는 (knife-edged selectivity) 방법과 연령별 선택비를 고려한 (age specific selectivity) 방법의 두 가지가 있으며 연령별 선택비를 고려하지 않는 방법의 경우 가입당 자원량의 식에 성숙비를 곱함으로써 가입당 산란자원량을 나타낼 수 있다. 하지만 기존의 가입당 산란자원량 추정 방법은 어구가입 이후의 모든 연령을 고려하지 않고 어구가입 연령의 성숙비만을 가입당 자원량에 곱함으로써 가입당 산란자원량을 계산하였다. 본 연구에서는 이를 수정하여 어구가입 이후의 모든 연령을 고려한, 즉, 연령별 자원량에 대해 가중평균된 성숙비를 가입당 자원량에 곱하여 가입당 산란자원량을 추정하였다. 한국 근해에서 유자망에 의해 어획되는 참조기자원을 대상으로 기존의 방법과 새로운 방법을 적용하여 추정된 가입당 산란자원량을 비교한 결과 어구가입연령의 성숙비가 1.00 이상에서는 가입당 산란자원량이 차이가 없었다. 그러나 성숙비가 1.00 미만인 연령에서는 어구가입연령이 낮을수록 오차가 크게 나타났으며 기존 방법에 의해 가입당 산란자원량이 과소 추정되었고 어구가입연령별로 가입당 산란자원량의 오차 값을 비교하였을 때, 적게는 4세 때의 0.25 g에서 많게는 1세 때의 130.69 g만큼의 오차가 나타났다. 또한 연령별 선택비를 고려하지 않는 방법과 연령별 선택비를 고려한 방법을 통해 $F_{35%}$를 비교한 결과 연령별 선택비를 고려하지 않는 방법 중 기존 방법에 의한 $F_{35%}$가 0.349/year로 나타났으며 새로운 방법에 의한 $F_{35%}$가 0.302/year로써 새로운 방법에 의한 값이 연령별 선택비를 고려한 방법에 의한 $F_{35%}$인 0.320/year와 유사하게 추정되었다. 따라서 본 연구에서 제시된 새로운 가입당 산란자원량 방법은 대부분의 어구가입연령이 2세 미만으로 낮게 나타나는 한국 연근해 어종을 대상으로 가입당 산란자원량 모델을 통해 자원평가를 실시할 경우 가입당 산란자원량과 그에 따른 적정어획수준의 오차 값을 줄여줄 것이며 기존의 방법을 통한 $F_{35%}$의 값은 과대 추정되어 남획의 위험이 있으므로 새로운 방법을 통해 적정어획수준을 추정하는 것이 옳다고 판단된다.

• 한국수산과학회지
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• 제57권3호
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• pp.292-301
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• 2024

It is challenging to simultaneously estimate parameters in a stock-recruitment relationship, steepness, and natural mortality rate with the other parameters within an age-structured assessment model even in a data-rich situation. Such a problem leads to uncertainty in estimates of management references such as maximum sustainable yield (MSY), which are affected by those components. The objective of this study was to evaluate the effects of those parameters on MSY by analyzing the process of estimating the MSY. For illustration, we used two data sets: The chub mackerel Scomber japonicus in the Korean waters and the yellowtail flounder Limanda ferruginea in the Southern New England-Mid Atlantic. As a result, the natural mortality rate influenced spawning stock biomass per recruit, yield per recruit, and MSY, while steepness affected MSY. A sensitivity analysis enabled us to estimate the natural mortality rate and steepness. The optimal set of steepness and natural mortality was 1.0 and 0.37 per year for the chub mackerel, and 0.35, and 0.8 per year for the yellowtail flounder, respectively.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2004년도 수산관련학회 공동학술대회 발표요지집
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• pp.368-369
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• 2004

• 수산해양기술연구
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• 제42권4호
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• pp.240-258
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• 2006

The potential of ecosystem-based fisheries management is recently recognized to be very important to improve the sustainability of fisheries resources. Under the depressed condition of many fisheries resources, this recognition has been expanded and more effort has been taken to improve this approach. Taking ecosystem concept includes the use of other tools of management in addition to fisheries regulation, such as stock and productivity enhancement, provision of physical structure, or marine protected areas. In the ecosystem-based fisheries management approach, it would require to holistically consider ecological interactions of target species with predators, competitors, and prey species, the effects of climate on fisheries ecology, the complex interactions between fishes and their habitat, and the effects of fishing on fish stocks and their ecosystem. Fisheries management based upon the understanding of these factors can prevent significant and potentially irreversible changes in marine ecosystems caused by fishing. A useful approach for analyzing tropho-dynamic interactions and mass-balance in marine ecosystems is introduced to demonstrate the complexity and usefulness of the ecosystem approach, which was applied to a small ecosystem in Korea. Korea should seriously consider to take the ecosystem-based approach to fisheries management, since most major fish stocks are currently depleted due to many reasons such as overfishing, land reclamation and coastal pollution.

• 수산해양기술연구
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• 제50권4호
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• pp.467-475
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• 2014

This study was performed to estimate optimum fishing mortality (F) and the age at first capture ($t_c$) for small yellow croaker in Korean waters. We first estimated optimum F and $t_c$ using traditional yield-per-recruit (YPR) analysis, and the results were 0.8/year and 2.5 years old, respectively. However, the individual fish price per unit weight of small yellow croaker in Korea increases dramatically by size. Thus, we developed an alternative method, which is called as production value-per-recruit (PPR) analysis. We developed two types of the PPR analysis, that is, the discrete function and the continuous function method. We estimated optimum F and $t_c$ using the two types of the PPR analysis and compared the results. The optimum F and $t_c$ from the discrete function method, were 0.3/year and 5.0 years old, respectively, while those from the continuous function method were 0.5/year and 3.5 years old, respectively. These PPR estimates were much more conservative for the stock management than the traditional YPR analysis, which can prevent the fish stock from the economic overfishing. As a result, the PPR analysis could be more proper approach for stock assessment in the case that the individual fish price per unit weight increases dramatically by size like small yellow croaker in Korea.

• 수산경영론집
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• 제23권2호
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• pp.53-67
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• 1992

It has been recognized, virtually from the time of its inception, that fisheries economics, like other aspects of resource economics, should ideally be cast in capital-theoretic terms. The fish population or biomass can be viewed as a capital stock in that, like conventional or man-made capital, it is capable of yielding a sustainable consumption flow through time. This study is to introduce the optimal control theory which was extended from the theory of calculus of variations into the study of former static theory of fisheries economics started by Gordon (1954). The optimal control theory eliminated the inadequacies of the classical techniques to a large extent. From this point of view, this study, on the base of Schaefer model, summerizes most of major results achieved so far, but does so in a manner such that the links with capital theory are made transparent. This study explores two sets of problems. The first concerns the optimal approach to the equilibrium stock, i.e. the optimal investment policy. The second set of problems arises from the relaxation of the highly restrictive assumption of autonomy (i.e. the assumption that the parameters are independent of time), then concludes the relaxation of linearity assumption together with the complexities caused by that.

• 수산해양기술연구
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• 제50권4호
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• pp.583-594
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• 2014

This study was performed to estimate biomass and provide management guidance through population ecological characteristics, including growth parameters, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus of Korea. For describing growth of this species, a von Bertalanffy growth model was adopted. The von Bertalanffy growth parameters estimated from a non-linear regression for starry flounder were $L_{{\infty}}=48.25cm$, K=0.16/yr, and $t_0=-1.48$, respectively and those for olive flounder were $L_{{\infty}}=86.46cm$, K=0.26/yr, and $t_0=-0.29$, respectively. Biomass of Platichthys stellatus was estimated by direct biomass estimation method was 2.6 M/T, that was estimated by indirect method was 13.4 M/Tt. Those of Paralichthys olivaceus were estimated as 10.1 M/T, 19.3 M/T, respectively. An yield per recruit analysis showed that the current yield per recruit on Platichthys stellatus was about 48.2 g with F=0.646/yr and the age at first capture ($t_c$) 1.35yr, that on Paralichthys olivaceus was about 167.6 g with F=1.121/yr and the age at first capture ($t_c$) 1yr.