• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.53 no.6
• /
• pp.942-953
• /
• 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%.

• The Journal of Fisheries Business Administration
• /
• v.33 no.1
• /
• pp.1-18
• /
• 2002

The observer program is being utilized In various fishing areas and fisheries internationally and nationally due to the its expected effectiveness in fisheries management and the collection of bioeconomic data necessary in fisheries management policy. The timely gathered data by observers play substantially a major role in decision-making fisheries policy such as the change in management measures, the application of season closure and area closure and etc. The expected effectiveness of the observer program In fisheries management, generally mentioned, is that it would lead to the increase in stock size from which the level of harvest would consequently increases. This study is aimed to analyze this tentatively expected effectiveness of the observer program in fisheries management. The changes in stock size and the level of harvest over time are analyzed under the observer program assuming the fishermen bear the cost of the observer program by investigating the change in fisherman's fishing activity under the observer program and by combining this changed activity with the biological model. The level of fishing efforts of fishermen was decreased from the results of the increase in fishing cost caused by the observer cost and the decrease in catchable stock size restricted by observers. This reduced level of fishing efforts enables stock size to increase over time and therefore, the expected level of harvest increases as time goes on. Another benefit under the observer program is to reduce management costs from the fact that fishermen are responsible for the cost of the observer program and the avoidance cost of fisherman responding to the fisheries regulation could be eliminated from the surveillance of observer. Therefore, it may possible to accomplish the cost-efficient fisheries management policy.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2000.05a
• /
• pp.328-329
• /
• 2000

This research is to estimate population parameters of the Korean horse mackerel stock and to determine the status of the stock. Considering the linkage of recruitment with the variation of environmental conditions in the early life history, acceptable biological catch (ABC) of horse mackerel was estimated. (omitted)

• Fisheries and Aquatic Sciences
• /
• v.26 no.3
• /
• pp.216-223
• /
• 2023

Pacific yellowtail emperor, Lethrinus atkinsoni Seale, 1910, is one of the most targeted reef fish species in Southern Sulawesi, Indonesia. Therefore, assessing its stock is important to understand the condition of the population, providing valuable inputs for sustainable fisheries management in the area. Here we assess the stock condition of L. atkinsoni in Southern Sulawesi, Indonesia, using the length-based spawning potential ratio model. A total of 4,887 individuals were collected from commercially small-scale fishers from January to October 2022. The total length, sex, and gonad maturity of the individuals were examined. We observed that the fish length ranged from 10.5 to 39.5 cm, with an average length of 23.3 cm. The sex ratio was equal (1:1.2) between male and female individuals. Length at first maturity and length at first capture were 23.4 and 19.6 cm, respectively. In addition, we observed a growth coefficient of 0.45/year, with an asymptotic length of 41.14 cm and natural mortality of 0.6/year. Based on these life history parameters, we observed the spawning potential ratio (SPR) value of 12%, indicating an unsustainable fishery level (SPR of < 30%). Further concerns related to the sustainability of the species and strategy to rebuild stock of the L. atkinsoni in Southern Sulawesi are of utmost importance.

• The Journal of Fisheries Business Administration
• /
• v.35 no.1
• /
• pp.1-22
• /
• 2004

Since the red grouper stock was initially declared to be overfished by the NMFS in September 2002, the Gulf of Mexico Fishery Management Council must prepare for the red grouper rebuilding plan considering the following alternative management policies: Total Allowable Catch(TAC), 5 - month season closure, 1800 - pound trip limit, and 50 - fathom longline boundary. The first concern the Council has is to evaluate the effects of recommended policies and the second is to analyze the impact of management policies on yellow edge grouper. This is because the fleets harvest red grouper also catch yellowedge grouper, the regulations on red grouper are likely to allow fishing effort to be distributed into yellowedge grouper. Therefore, this study is aimed at evaluating the biological and economic effects of management policies considering simultaneously the impact of red grouper regulations on yellow edge grouper by developing a combined red grouper and yellowedge grouper bioeconomic model. The overall results indicate that management policies for red grouper would adversely affect the yellowedge grouper stock if yellowedge grouper is not protected by its regulations. The TAC policy has the most serious impact on the yellowedge grouper stock, while the 1800 - pound trip limit policy minimizes the reduction in the yellowedge grouper stock. However, the target stock size of red grouper is achieved as well as the largest net present value of returns is gained in the TAC policy.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2000.05a
• /
• pp.327-327
• /
• 2000

In the 1990's several economically important marine fisheries collapsed or showed signs of extreme hardship owing to overcapitalization and excessive fishing pressure on the resources. Public concern was raised and demands voiced for more prudent fishery management practices. The United Nations responded and developed international guidelines, such as the FAO Code of Conduct for Responsible Fishing and the UN Straddling Fish Socks and Highly Migratory Fish Stocks Agreement These guidelines task fishery managers to take prudent steps to ensure the long-term viability of fisheries and fishery resources. Included in the guidelines are two particular demands that will challenge stock assessment scientists in the new millennium. They are application of the precautionary approach and the inclusion of ecological considerations in assessments and management advice. High-lighted in the presentation are examples from the central-western Pacifi skipjack tuna fishery and the eastern Pacific thresher shark fishery where insufficien information is affecting stock assessments. The shortcomings are further linked t the new challenges of applying the precautionary approach, such as reference points, and ecological considerations, such as predator-prey and oceanographic-regime shift.(omitted)

• Journal of Fisheries and Marine Sciences Education
• /
• v.19 no.1
• /
• pp.34-52
• /
• 2007

This study analyses the management and utilization of Korean inland fisheries and suggests directions for reorganizing the fisheries in order to achieve qualitative growth. Inland fisheries developing into a unique fishery according to various aquatic systems in different areas have played various roles such as the efficient use of aquatic resources, development of local areas and economy vitalization in under-developed local areas. However, recently Korean inland fisheries are facing a lot of difficulties due to the circumstantial changes surrounding the fisheries. Even though it is difficult to expect the external expansion of the Korean inland fisheries, we could expect qualitative internal growth by achieving the sustainable management and aquatic ecosystem health. Therefore, this study suggests the followings in order to achieve the qualitative growth of the Korean inland fisheries : first, construction of integrated management system according the aquatic systems ; second, organization of fishermen's interest groups such as cooperatives or associations in order to increase the competitive advantage and spread voluntary fisheries management ; third, boosting stock enhancement through systematic stock assessment and stocking ; fourth, expansion and activation of administrative system and research organizations.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.4
• /
• pp.445-451
• /
• 2012

We developed an age-based spawner-recruit model incorporating environmental variables to forecast stock biomass and recruits of pelagic fish in this study. We applied the model to the Tsushima stock of jack mackerel, which is shared by Korea and Japan. The stock biomass of jack mackerel (Trachurus japonicus) around Korean waters ranged from 141 thousand metric tons (mt) and 728 thousand mt and recruits ranged from 27 thousand mt to 283 thousand mt. We hind-casted the stock biomass to evaluate the model performance and robustness for the period of 1987~2009. It was found that the model has been useful to forecast stock biomass and recruits for the period of the lifespan of fish species. The model is also capable of forecasting the long-term period, assuming a certain climatic regime.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.44 no.4
• /
• pp.345-352
• /
• 2008

A self-regulatory community fisheries management program in Korea is designed to enhance fisheries resources, to protect fishing grounds of self-regulatory communities, and to manage their fisheries resources by their own regulations and knowledge. This study explored an applicable ecosystem-based management plan based on the scientific investigation and analysis. This study suggested objectives, indicators and reference points of the ecosystem-based resource management system which are applicable to selfregulatory community fisheries. The objectives of the management system are to maintain sustainable fisheries production, to maintain optimum fishing intensity, to reduce by-catch, to conserve spawning ground and habitat, to maintain optimum habitat environment, to increase/maintain abundance of prey species, to increase/maintain stock biomass, and to conduct stock enhancement on the basis of scientific assessment. The improved methods for the assessment and management are introduced by demonstrating a self-regulatory fishery which targets on hen clam in Dong-li fishing village in Busan.

• Journal of Fisheries and Marine Sciences Education
• /
• v.16 no.1
• /
• pp.99-109
• /
• 2004

This study analyzed the multivariate impacts of subsidies on the sustainability of fish stock using a dynamic bioeconomic modeling and fisheries resources economic approaches for understanding impacts of a subsidy on the sustainability of a fish stock. According to the results of analysis, the conclusion of former studies is true only there are imperfect control of fishing effort and enforcement under management rerime and under open access. However, if there are perfect control of effort and enforcement, the subsidies do not give any negative impacts on the sustainability of fish stock. Further, if even so-called bad subsidy is also provided necessarily in response to the condition of fishing industry and the characteristic of fishermen, it can give positive impacts on fishing income by which fishermen can improve their fishing condition.