• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.2
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• pp.208-217
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• 2021

This study described the fishing characteristics of Pacific herring Clupea pallasii and examined the relationship between its catch and sea temperature in Korean waters from 1970 to 2019. Although the herring catch in Korean waters stayed below 1,000 tons per year from the mid-1970s to mid-1980s, the catch in the winters in the East Sea of Korea started to increase markedly after 1987-1988, when the sea surface temperature (SST) seemed to shift to a warmer regime. Since the mid-2000s, overall, herring was caught throughout the year in the East Sea and eastern South Sea of Korea, and its catch significantly increased by around 30,000 tons per year. The main fishing grounds of herring in the poor fishing years until the mid-1980s were possibly formed in the western offshore of Korea, and subsequently the fishing grounds were distributed in the eastern coast of Korea. While the standardized catch per unit effort (CPUE) for two main fisheries of herring catch was significantly correlated with the herring catch since the 2000s, there was a gradual decline since the 2010s. The herring catch in the East Sea had significant positive correlations with SSTs, but that in the West Sea had a significant negative correlation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.934-941
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• 2020

The spatial and temporal catch variations of Argentine shortfin squid Illex argentinus in the Southwest Atlantic Ocean (SWA) were analyzed using Korean squid-jigging fishery data collected through electronic reporting system (ERS) from 2016 to 2020. The ERS linked with GPS has been implemented for collecting fishing data from all Korean fishing vessels operating in international waters since November 2015. The fishing period of the Korean squid-jigging fishery in the SWA runs from early summer to autumn (December to June) in the Southern Hemisphere. The fishing ground was extended from 42°S to 48°S along the Patagonian continental shelf and slope, and the main fishing ground was formed around the Falkland Islands. The yearly catch per unit effort (CPUE) of I. argentinus fluctuated between 1.69 and 7.53 tons/day. In this study, during the fishing season, a south and westward shift on the fishing ground was observed indicating the feeding migration of the south Patagonian stock. The shift in monthly fishing centroids differed according to fishing season. The gradual southward shifts of fishing centroids were observed in the catch years (2017 and 2018), whereas unapparent shifts in fishing centroids were observed in the low catch years (2016 and 2019).

• The Journal of Fisheries Business Administration
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• v.29 no.1
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• pp.65-88
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• 1998

The sustainable reduction of the fisheries resource is keenly raised an urgent problem of the fisheries policy in Korea, China and Japan. Then, 3 country, Korea, Japan, China, have established various system for fisheries resource management. Among these systems, qualitative fishing regulations have been commonly established. For example, its have been enforced to the prohibited fishing region, fishing period, fish size, net size, specified fishing methods. Also, different fisheries resource management policies have occasionally enforced by each country. For example, the prohibition of free sale and free possession has been established in Korea and Japan, but not China. And, In Korea, It has been enforced uniquely to entry system far fishing license number ana sea farming project for coastal fishing grounds by national government. The entry system for fishing license number has been enforced in Japan too, not national government, but local government. Nevertheless these three countries have put good system for fisheries resource management above mentioned, real enforcement has been not operated well. For efficient management on same fisheries, next problem will have been solved. First, it has to be guaranteed to transparency on the fisheries management, which is considered the priority problem on the fishing regulation. For reason, although efficient system is established in each country, if feasibility of the system was not trusted, mutual effort like that is very difficult to gain desired results. Then, each country has to establish transparency on the fisheries statistics and administration. Second, it has to be adjusting on the criteria or level of fisheries resource management. Now Korea, Japan and China have different criteria or level of fisheries resource management, for, example, prohibited fish size and prohibited fishing net sine. To solve above problems, three countries need to deeply discuss together. Then fisheries resource co-management scheme should be established in same fishing ground.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.359-364
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• 2001

This paper presents case studies on the multi-species fisheries in Korean waters, Multi-species fisheries were divided into two types, that is, multi-species by a single fishery and single species by multiple fisheries. For the case of single species by multiple fisheries, the small yellow croaker stock caught mainly by the Korean pair trawl fishery and the Korean stow net fishery was selected. This approach uses both standardized fishing efforts for the two fisheries by a general linear model and some data for the economic analysis, and then estimates maximum sustainable yield (MSY), maximum economic yield (MEY) and fishing efforts for MSY and MEY, An analysis of interaction aspects between pair trawl and stow net fisheries was carried out to predict the optimal level of fishing effort from the economic point of view, which gives the largest benefits to the two fisheries.

• The Korean Journal of Applied Statistics
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• v.28 no.5
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• pp.847-858
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• 2015

Deep-sea fishery in the Antarctic Ocean has been actively progressed by the developed countries including Korea. In order to prevent the environmental destruction of the Antarctic Ocean, related countries have established the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and have monitored any illegal unreported or unregulated fishing. Fishing of tooth fish, an expensive fish, in the Antarctic Ocean has increased recently and high catches per unit effort (CPUE) of fishing boats, which is suspicious for an illegal activity, have been frequently reported. The data of CPUEs in a fishing area of the Antarctic Ocean often show an extreme Distribution or a mixture of two extreme distributions. This paper proposes an algorithm to detect an outlier of CPUEs by using the mixture of two extreme distributions. The parameters of the mixture distribution are estimated by the EM algorithm. Log likelihood value and posterior probabilities are used to detect an outlier. Experiments show that the proposed algorithm to detect outlier of the data can be adopted instead of simple criteria such as a CPUE is greater than 1.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.2
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• pp.173-184
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• 2021

In this study, internationally widely utilized bioeconomic models were used to make a comparison and analyze the effectiveness of red snow crab fisheries management measures. As a specific effect analysis, biological and economic effects of both total allowable catch (TAC) and effort reduction management measures were analyzed simultaneously. Model results showed that the red snow crab biomass would be decreased from 106,000 tons to 73,076 tons after ten years when the TAC is set to and maintained at the current level of 26,000 tons. The amount of biomass would be increased to 125,316 tons when the level of TAC is set to 22,000 tons. In cases of reduced fishing efforts, a 30% decrease from the current level would result in greater biomass and NPV would be also estimated at the highest level. In addition, a sensitivity analysis by market price was conducted to analyze the minimum TAC level of the red snow crab offshore pot fishery. Results showed that the minimum TAC level would be 8,210 tons when the market price increased by 30% and it would be also 15,247 tons when the market price decreased by 30%. Furthermore, results of the sensitivity analysis by fishing cost showed that the minimum TAC level was analyzed to be 13,857 tons when the fishing cost increased by 30% from the current level.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.311-326
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• 2005

The paper deals with the problem of selective harvesting in a prey-predator model with predator self limitation. Criteria for local stability and global stability for both the exploited and unexploited system are derived. The effort has been considered as a dynamic variable and taxation as a control instrument to protect the fish populations from over exploitation. Finally, the optimal taxation policy is discussed with the help of control theory.

• The Journal of Fisheries Business Administration
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• v.46 no.3
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• pp.73-82
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• 2015

This study aimed to evaluate the effectiveness of closed season policy using an integer linear programming, targeting the large purse seine fishery in Korea. In the analysis, based on Cheng and Townsend(1993), fishing effort (fishing days by month) was assumed to be distributed for profit maximization of vessels and catch of immature fish was estimated. The analytical results showed that the effects of closed season policy would vary in accordance with the monthly closures in terms of fishing profits and catch of immature fish. A closed season policy by month had different effects on fishing profits and catch of immature fish by species. It implies the importance of considering seasonal changes of fish species when limiting fishing efforts with the closed season policy.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1053-1062
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• 2015

This research assesses the implementation of the bilateral fisheries order of the China-Japan fisheries agreement. After establishment of UNCLOS, the China-Japanese fisheries agreement has played as a basis for the fisheries order in the East China Sea. The China-Japanese fisheries agreement intends that the fisheries industries in China and Japan can utilize the renewable natural resources in the East China Sea. As the EEZ of China overlaps with that of Japanese in the East China Sea, the two countries established the China-Japan Provisional Measure Zone and Middle Zone in the Sea. Even though the three coastal States (e.g. Korea, China, and Japan) in the East China Sea are involved in managing these zones, there has been little effort to coordinate each county's management. Additionally, the Taiwan-Japan fisheries agreement, which is for the area of N $27^{\circ}$, has made costal States to establish and implement united measures to conduct effective fisheries management. Regarding access to the joint fishing zone in EEZ, Chinese fisheries regulations have been enforced in the zone because the fishing capacity of China exceeds all of other countries, reducing the number of fishing licenses and catch quotas. It turned out that a nation that has authority over fisheries resources tends to establish specific conditions of fishing operations to maximize its national interest. In the China-Japan Provisional Measure Zone, Chinese and Japanese authorities have introduced united measures to manage fisheries resources. However, in the Middle Zone between China and Japan, there is no regulation on fishing; both countries' fishing vessels can have free access to the zone. Thus, it is recommended that one should introduce an international fisheries management regime for the Middle Zone. In this regard, Korea should play a leading role in establishing the international management regime because Korea has middle position in terms of geographical standpoint, the degree of dependence on commercial fishing, and its fishing capacity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.476-486
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• 2010

Fishing efficiency of a trawl vessel can be enhanced by increasing the swept area per unit time, which can be attained either by increasing the mouth size of the net, or by increasing the towing speed. To improve fishing and fuel efficiency of trawl vessels targeting fishes of greater mobility, in which the towing speed is more critical in determining fishing efficiency, we conducted a series of model tests to evaluate the performance of the newly-designed nozzle propeller before installing it in a trawl vessel to verify its towing speed and fuel efficiency in the sea. By conducting further model tests in the experimental basin, we redesigned the propeller of stern trawler to improve the resistance and propulsion performance. Through actual fishing operations, we evaluated the improvement in fuel and fishing efficiency by installing the new nozzle propeller. The trawling speed increased by 0.6kts at the same engine power (RPM), while the engine margin increased by more than 20%. The increased towing speed by installing the redesigned propeller is expected to enhance fishing performance through increasing the number of hauling- and casting operations per unit times, while shortening the towing duration. Analysis of the Catch-Per-Unit-Effort (CPUE) data indicated that the mean CPUE of trawl fishery increased from 3.04kg/m in year 2007 to 6.15kg/m in year 2008, confirming enhanced fishing efficiency by adopting the redesigned propeller.