• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.413-424
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• 2005

The study focused on the fluctuation of the fisheries conditions in fishing ground of yellow croaker, Pseudosciaena polyactis Bleeker. A long-term decreasing trend was observed in the accumulated catches of the species since 1926, with increasing-decreasing fluctuation repeating 6 times. Periodicity was observed in 10-year interval in good fishing years, but not in poor fishing years which had irregular fluctuations. From the geographical distribution of the past catch per unit effort, it was presumed that a group of the species seasonally migrated but most of the groups stayed throughout year in the western area off Cheju Island, which was different from the assumptions of the 1970's. The fishing grounds were distributed along the migration route differently by season, throughout the Yellow Sea and the East China Sea, but shifted gradually southward and narrowed down to the area of $32^{\circ}N-125^{\circ}E$ off Cheju Island, where the center of fishing grounds was given birth to throughout the year with a relatively high density from autumn to spring. It was noted that a negative correlation was shown between the area of fishing grounds and density distribution of catch.

• The Journal of Fisheries Business Administration
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• v.36 no.3 s.69
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• pp.1-24
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• 2005

Korean fishery wage system has been evolved with the different titles. However, Since the law of fishing crew was enacted in 1984, the fishery wage system has been established as a rate system, which is a legal term. The present rate system in practice shows various contents and modalities, depending on fisheries and regions, but the fisheries of large trawl cooperative employ a rate system of fixed plus rate wage. However, such change did not transform basically the properties of pure rate scheme. As well known, fishing vessel owners face an awful lot of difficulty in managing and controlling effectively the production process because fishing activities are carried out in the seas remote from the land. Thus, it tend to be inevitable for vessel owners to employ a rate system to induce fishermen's positive motivation for promoting productivity and saving operating costs. However, the rate system has worked out as a driving force, which induce an increase in production more strongly under the expansion of vessel numbers and power and the keener competition of fishing activities. Even though the control mechanism of fishing instruments are well established, fishermen become naturally to have an incentive to increase their fishing effort for maximizing production since they are able to raise their shares by maximizing the quantity harvested. Thus, as far as the rate system exists, fisheries administration may have much difficulty in realizing its fishery management goals only through vessel reduction and fishing gear regulations. Also, under the rate system fishery management authority may be in face of a serious dilemma between the spontaneous rate system and vessel reduction policy. If the realistic aspect of the rate system is recognized and resource restoration and profit promotion are main policy goals, it is necessary to develop effective ways to control vessel owners' and fishermen's production-maximizing motives at an appropriate level. From this point of view, it seems reasonable to introduce TAC system by species or by fisheries into the existing fishery system. The research results suggest that if the fisheries administration could understand clearly the spontaneous fisheries wage system, it would know the norm of TAC and the basic reasons for illegal fishing activities and thus it would be able to develop and implement more realistic resource management policies.

• The Journal of Fisheries Business Administration
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• v.49 no.1
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• pp.67-89
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• 2018

In fisheries, as well as in other natural resource-based industries, there is difference between profit and rent. The former is a basic indicator for gauging the business performance of firms, while the latter is for the evaluation of the contribution of resources and industry to economic welfare. Put simply, resource economists are mainly concerned about rent, including pure resource rent and producer surplus (intra-marginal rent [IMR]). In other hand, business economists are mainly concerned about the profitability of the firms comprising the industry. In the academic literature, there are not always clear definitions of the profit and rent concepts and their use in actual analyses. This article will mainly discuss and clarify differences and similarities in profit and rent concepts. In the classical fisheries economic model with one-dimensional homogenous effort and a constant cost per unit of effort, no rent exists in open-access equilibrium. A simple change in this model, for example by introducing heterogeneous effort, opens it to the existence of rent, specifically IMR, at open-access equilibrium. We estimated resource rent and profit from the data using SNA(system of national accounts) and accounting data methods. RR(resource rent) is composed of value-added, compensation of employees, consumption of fixed capital and normal profit in SNA. RR(resource rent) is composed of EBT, Depreciation of fishing rights, financial costs of fishing rights and calculated interests on equity in accounting data methods. We found that the result of two methods is equal. RR is composed of excess profit, rent and interest expenses. In Korea, the magnitude of RR and profit is not different significantly.

• The Journal of Fisheries Business Administration
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• v.33 no.2
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• pp.31-48
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• 2002

This paper is aimed to analyze how to evaluate the choice of optimal management measures and level of control in fisheries management under the costly and imperfect management system by comparing with costless and perfect management system that is commonly assumed in the analysis of fisheries regulations. Fishermen would set the level of fishing efforts at the point where the marginal fishing profit for fishing effort is equal to the marginal level of fine under costly and imperfect management system. Therefore, under the case where the marginal fishing profit is higher than the marginal level of fine, the level of fishing efforts would be made at the point which is higher than the level of fishing efforts made under costless and perfect management system and is not a point where the economic profit is maximized in regulated fisheries. From this conclusion, the fishermens avoidance activities against regulations as well as the level of control in fisheries management substantially have an influence on the choice of fisheries management instruments. According to the analysis of optimal fisheries management policy, the economic profits in regulated fisheries are determined by the level of fisheries enforcement costs and total fishing profits, in which as enforcement costs increase the economic profits decrease. In addition, the economic profits vary in response to the level of control in avoidance activities. That is, as avoidance costs decrease, the economic profits increase. The determination of optimal level of control in fisheries management should be made at the point where the marginal regulation costs are equal to the marginal profits from regulated fisheries, in which marginal regulation costs are different according to the type of management measures. And the level of profits changes in response to different levels of avoidance activities. The management measure that can maximize the difference between the marginal regulation costs and marginal profits from regulated fisheries should be chosen as an optimal fisheries management instrument.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.232-248
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• 2004

In order to utilize fisheries resources under a joint management scheme with adjacent nations, as well as detecting of fishing grounds, the factors which influence yellow croaker (Pseudosciaena polyactis) in Korean waters were studied using historical catch per unit effort and oceanographic data. The main fishing ground near Cheju Island was located along the thermal front formed between the Yellow Sea Bottom Cold Water (YSBCW) and northward moving warm current. When the YSBCW (index temperature: $10^{\circ}C)$ strongly extended southward, the fishing condition were worse than average. Especially, low temperatures greatly influenced stow net fisheries, which were operated in the deep water layer The concentration and dispersal of fishing ground and catch coincided with oceanographic features and the seasonality of water masses.

• The Journal of Fisheries Business Administration
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• v.27 no.2
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• pp.65-82
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• 1996

This study aims to investigate the development of the stow-net fishery operated in East China Sea and Yellow Sea and its role in the off-shore demersal fishery In Korea after 1980's. This paper also reorganization problems of this fishery under 200 mile exclusive economic zen system. Stow-net fishery which has an important role in offshore demersal fishery in terms of the fish production and supplies had attained an rapid growth since 1960's throughout advancement of the fishing technique, government support and enlargement of fish market. However, the production had come to a stagnant stage since 1980, and even reduced in 1990's by reason of competition from Chinese vessels which have been developing reapidly as well as other more productive demersal fishery such as trawl of Korea. Nevertheless, high fish price has maintained the business of this fishery. This fishery faces some difficulties such as limited resources, the plunge of fish price due to fish import freedom, and 200 mile EEZ settlement in those Seas among the related countries ratifying the United Nations Convention of the Law of the Sea in 1996. This paper discusses the reorganization problems of the stow-net fishery under the new situation. : (1)to lighten a damage to the fishery to keep the fishing ground and to restrict the entry of competitive fisheries, (2)to reduce the fishing effort by the governmental support, (3)to introduce new fishing methods, (4)to employ foreigner as a cheep labour, (5)to rise fish price throughout more freshness of fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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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%.

• Environmental and Resource Economics Review
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• v.26 no.4
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• pp.613-639
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• 2017

A Maximum Entropy (ME) Model and an Analytical Model are analyzed in assessing Kapenta stock in Lake Kariba. The ME model estimates a Maximum Sustainable Yield (MSY) of 25,372 tons and a corresponding effort of 109,731 fishing nights suggesting overcapacity in the lake at current effort level. The model estimates a declining stock from 1988 to 2009. The Analytical Model estimates an Acceptable Biological Catch (ABC) annually and a corresponding fishing mortality (F) of 1.210/year which is higher than the prevailing fishing mortality of 0.927/year. The ME and Analytical Models estimate a similar biomass in the reference year 1982 confirming that both models are applicable to the stock. The ME model estimates annual biomass which has been gradually declining until less than one third of maximum biomass (156,047 tons) in 1988. It implies that the stock has been overexploited due to yieldings over the level of ABC compared to variations in annual catch, even if the recent prevailing catch levels were not up to the level of MSY. In comparison, the Analytical Model provides a more conservative value of ABC compared to the MSY value estimated by the ME model. Conservative management policies should be taken to reduce the aggregate amount of annual catch employing the total allowable catch system and effort reduction program.

• Environmental and Resource Economics Review
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• v.15 no.1
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• pp.71-94
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• 2006

Reducing fishing capacity is one of hot issues in the world fisheries. Increased fishing capacity causes not only fish stocks to be depleted, but also additional fishing costs to be incurred, resulting in reductions of fishing profits. In order to achieve a sustainable and profitable development of fisheries, it is inevitable to reduce fishing capacity. For this reason, FAO adopted 'the International Plan of Action for the Management of Fishing Capacity' and recommended member countries to estimate fishing capacity and to implement the policy to reduce fishing capacity. This study is aimed at measuring fishing capacity of Large Purse Seines Fishery using a Data Envelopment Analysis (DEA). The DEA result showed that the practical catch of large purse seine fishery in 2003 was 158,662 tons, but the capacity output for current input was 318,397 tons. The capacity utilization is about 50%, it is obvious the capacity did not utilize enough. The sensitivity analysis on DEA results indicated that the number of ships (including tonnage and horse power) should be scrapped by 50% or days fished should be reduced by 63% if the present catch remained. In addition, if the catch remains at the MSY base level of large purse seines, the analysis suggested that the number of ships (including tonnage and horse power) should be reduced by 30%, otherwise days fished should be reduced by 60%.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.884-889
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• 2002

This paper was carried out from 15 June to 24 December in 2000 in Lake İznik of Turkey, to determine catch per unit effort (CPUE) and size composition of crayfish, Astacus leptodactylus Eschscholtz 1823, captured by fyke-nets of local fishermen. The average CPUE of all size groups was found as 1.65 crayfish/fyke-net/night for fishing season in 2000, but 26.4% of which was below the legal minimum size (crayfish<90 mm). The average CPUE of legal-sized (crayfish$\geq$90 mm) crayfish was 1.10 crayfish/fykenet/night. The annual catch of crayfish was estimated as 2990 tonnes. The length and weight compositions of crayfish captured in the fyke-nets have varied between 60 and 130 mm, and 6 and 71 g, respectively. The mean length and weight were found as 95.5 mm and 28.8 g for all size groups and 100.1 mm and 33.0 g for legal-sized individuals.