• Ocean and Polar Research
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• v.28 no.1
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• pp.25-35
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• 2006

Fisheries buyback programs have been implemented from 1994 in Korea, and its scale is estimated to have a value of 930 billion won, which is compounded for eight years since 1994. The paper evaluates the programs' economic and financial viability, and predicts efficient ways about how much and how long to reduce fisheries vessels so as to pursue a target biomass at MSY, For the specific purpose of the paper, aggregate fisheries stock dynamics and catch functions are specified and estimated by yearly catch and fishing effort data from 1970 to 2001, using ASPIC model and Schaefer's logistic production model. Results show that the fisheries stock in Korea has steadily declined since 1970, and that Korean fisheries overexploitation has steadily increased. Using cost-benefit analysis method, the buyback program holds the economic and financial feasibility even if the scale of buyback programs is not sufficient to avoid the downward trend in fisheries stock and harvest. The potential investment scale is predicted in several alternative scenarios using the sensitivity analysis method. The results recommend the annual reduction of 46%, 12% or 20% for the next one year, five years or three years, respectively so that the target biomass at MSY may be reached in 25 years.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.5
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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.

• The Journal of Fisheries Business Administration
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• v.33 no.2
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• pp.75-98
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• 2002

As a contribution to developing fishery stock assessment, optimum sustainable yield and its international standards such as MSY, MEY, and dynamic MEY for six recommended fisheries are developed using bio-economic models. For selecting the appropriate model, five models - Schaefer, Schnute, Walters and Hilborn, Fox, and CY&P models are tested in effort and catch data of six species. Surprisingly all the models except the CY&P model failed to satisfy statistical standards such as goodness-of-fitness and reliability. Generally, the CY&P model holds good fitness and statistically significant level for all of six fisheries. However, the CY&P model for squid, where the intrinsic growth rate is high, could not explain MSY, MEY, and dynamic MEY appropriately. This study makes a contribution to develop the modified model for the intrinsic growth rate of 1. The reformulated model represents the results reasonably even though the estimated equation has not good fitness. Although most of the CY&P models appear to have good fits and validated results for some cases, these models also seem to be quite sensitive to parameters which means a more stable model should be developed and data should carefully be handled. In particular biological and technical interactions such as multispecies, predator prey relationship, age structure and mortality should be taken into account. In addition, economic factors and fishing efforts such as price, cost, technical change and a reasonable function of fishing input should simultaneously be considered.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.185-193
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• 2021

This study was conducted to evaluate the performance of the octopus pot according to mesh sizes. Entering behavior of Octopus minor and bait (Macrophthalmus japonicus) escape rate on the mesh sizes of the pots were investigated for six times in indoor tank. The sea trials for evaluating the performance of Octopus minor pot to different mesh sizes (22, 20 and 18 mm) were conducted for six times from 2017 to 2018 in the coastal sea of Deukyang Bay, the Republic of Korea. Behavior patterns of contact pot to leaved pot were more frequent than contact pot to bait search. When the octopus contacted to the pot, there was no clear search behavior to distinguish the mesh sizes. Total catch of 46% was accounted for 18 mm pots, followed by 34% at 20 mm and 20% at 22 mm (P < 0.05). Catch per unit effort was calculated as 30 g/pot at 22 mm, 44 g/pot at 20 mm and 59 g/pot at 18 mm. As a result of evaluating 50% selection of mantle length and weight on the mesh sizes, mantle length (mm) and weight (g) were 84.6 and 147.8 in 22 mm, followed by 20 and 18 mm.

• Journal of Fisheries and Marine Sciences Education
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• v.13 no.2
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• pp.146-167
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• 2001

Korea and China are two opposite countries located aside Yellow Sea and co-utilize the East China Sea. The two countries are close together from geological point of view, however, the competitive development of resources was more emphasized than the cooperative development of resources between the two countries because the special policy relationship. Additionally, after the communist government of China was founded in 1949, the political conception between the two countries was quite different. Therefore the establishment of appropriate international fisheries co-operation was impossible, and the international management problems of fisheries resources in Yellow Sea and East China Sea were let alone. UN convention on the Law of the Sea came to force in 1994, Korea and China adopted the exclusive economic zone system in 1996. On the other hand, Fisheries Law in Korea was enacted in 1953 in order to management of fisheries resources, and also China was enacted fisheries law in 1986. The two countries control the fisheries effort through fisheries license system, meanwhile through prohibition fishing area, prohibition fishing period, limitation of net size, and limitation of body length to conserve and manage the fisheries resource. The serious management methods of resource management in the two countries are similar such as the creation of promptly decreased species and those species that have commercial value, discharge of fish seedling stock, settlement of artificial reef and clean of fishing ground. Therefore, the two countries should consider not only the improvement of formal law system, but also how to recover the fisheries resources in circumference water zone and how to improve the efficiency of fisheries resource management. Specially the settlement and management of artificial reef should be chosen in the area that have the highest benefit to two countries, and should establish the common management system of discharge of fish seedling stock. And the two countries should adopt the same criteria through technical management and limitation of net size, limitation of body length, and prohibition area of special fisheries to ensure the highest fisheries benefit of fisherman in the two countries and the highest efficiency of fisheries resource management.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.282-294
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• 2004

Catches of Argentine shortfin squid Illex argentinus showed a sharp decrease, reaching 99,000ton in 1993 and 56,700ton in 1994, and then increased again reaching 130,300ton in 1997 from 78,600 ton in 1996. The Korean squid jigging fishery around Falkland for Illex argentinus commences usually its operation in January and lasts August and peak in catch was showed from March to May. To elucidate possible environmental effects on their abundance during the main fishing season in 1993-1994 and 1996-1997, sea surface temperatures were used as an indicator of the position and strength of the oceanographic structures in the Southwestern Atlantic Ocean. The high catch and catch per unit effort of Illex argentinus was showed when the Faliland Current was not affected in the fishing area in 1993 and 1997. But they were sharply decreased from the middle of April 1994 and the late of April 1996 when the Faliland Current directly affects the fishing ground.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.4
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• pp.299-315
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• 2020

Tuna fisheries were applied to an integrated ecosystem-based fishery risk assessment method using indexes of target species status, inhabited species in a target ecosystem, habitat quality and socio-economic benefit of affected fisheries. This study suggested more effective and efficient management measures to break away from traditional management methods, such as limitation of catch and fishing effort. The results presented that the objective risk index (ORI_S) on sustainability of bigeye and yellowfin tunas by purse seine fishery was estimated high due to the high catch ratio of small fishes. The ORIs of biodiversity (ORI_B) and habitat quality (ORI_H) of purse seine fishery were also estimated at a high level from using fish-aggregating devices (FAD). However, due to skipjack tuna's high catches, the ORI of socio-economic benefit (ORI_E) was estimated at a very low level. Due to the high bycatch rate, ORI_B was high, and ORI_S and ORI_H were evaluated at a low level in longline fishery. Due to strengthern of fishing restrictions and increase of fishing costs, the ORI_E was assessed to be very high. The ecosystem risk index (ERI) for two tuna fisheries was assessed low, but the overall FAD management by purse seine fishery is necessary at the ecosystem level.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.25-30
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• 2007

In order to estimate the ecological parameters of the population, short-necked clams, Ruditapes philippinarum, were collected from Jindu coast at Hansan Island, from April to December in 2005. The growth of the clam was estimated by von Bertalanffy growth model and each parameters were obtained from a nonlinear regression as $L_{\infty}\;=\;48.8\;mm$, k = 0.28 and $t_0\;=\;-0.88\;(R^2\;=\;0.994)$. Instantaneous coefficient of total mortality (Z) and fishing mortality (F) was calculated to be 0.8614/yr. and 0.6122/yr, respectively. The age at the first capture was estimated to be 2.88 year. Using the present parameter for clam fishing, the yield-per recruit (Y/R) was estimated to be 3.44g. Although the maximum Y/R was obtained under the parameters ($t_c\;=\;3.48\;yr$. and F = 0.9295/yr), it is favorable to maintain the current fishing effort considering the annual fluctuation of the parameters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.208-214
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• 2021

It is necessary to consider the suicide problem of the senior citizens according to their occupation rather than simply dividing seniors according to whether they live in rural or urban areas to seek countermeasures against suicide. This study examines factors that influence the suicidal intentions of senior citizens engaged in the agriculture, forestry, and fishing industries using the ranking probit model. As a result, the suicidal intention of senior citizens working in the agriculture, forestry, and fishery industries who felt lonely increased by 3.0%, but the intention to commit suicide decreased by 1.1%, when they value their work, and the intent to commit suicide decreased by 2.7% when they feel a strong sense of belonging to their region. The more family members or relatives they meet every day, the suicide intentions of senior citizens in the agricultural, forestry, and fishing industries decreased by 2.5%. However, since the number of families living together is decreasing every year, there is an inevitable limit on face-to-face contact with family members or relatives. Therefore, it is necessary to establish policy that links the loneliness of senior citizens in the agricultural, forestry, and fishing industries with the effort of public institutions to promote social values.

• Environmental and Resource Economics Review
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• v.29 no.3
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• pp.363-388
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• 2020

The purposes of this study are to not only estimate optimal harvests and efforts using the surplus production methods for Spanish mackerel caught by multiple fishing gears, but provide dynamic optimal fisheries management for these gears using the current value Hamiltonian method. To achieve the above purposes this study uses several models such as Gavaris's general linear model for standardizing fishing efforts, surplus production method for estimating biological and technological coefficients, current value Hamiltonian method for estimating dynamic optimal harvest and efforts, and sensitivity analysis for diagnosing economic influences of these fisheries. As a result, this study showed that Spanish mackerel was overfished by multiple fishing gears based on surplus production method and the current value Hamiltonian method. Also, this study found that when the price and cost proportionally changed, the optimal harvest and fishing effort sensitively responded to the stock level of Spanish mackerel. Next, this study suggested that the multiple fishing gears for Spanish mackerel should reduce unnecessary costs such as operating time or inefficient fuel consumption. Finally, this study provided reasons Spanish mackerel should be included in the TAC system in a view of profit maximization based on sustainable use of the Spanish mackerel.