• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.594-597
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• 2013

Two leptocephali [total length (TL) 68.2-80.5 mm] from the family Ophichthidae, collected from the waters south of Jeju Island, Korea, were identified using morphology. The two ophichthid leptocephali were identified as belonging to the genus Ophichthus based on morphological characters: 131-132 myomeres; nine gut swellings; dorsal fin origin above the middle of the body; five postanal pigments present from the anus to the caudal margin. Ultimately, both leptocephali were identified as Ophichthus asakusae, as the total number of myomeres was consistent with those of adult O. asakusae. Here, we first describe the morphological characteristics of the O. asakusae leptocephalus, and suggest diagnostic characters for leptocephali belonging to the genus Ophichthus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.1-8
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• 2020

The reproductive biology of largehead hairtail Trichiurus japonicus, from near Jeju Island, Korea was investigated based on 4,384 individuals collected by commercial vessel from November 2016 to October 2019. There were more female specimens than male specimens (2.64:1). T. japonicus preanal lengths (PL) ranged from 10.5 to 53.5 cm; the relationships between PL and body weight (BW) were BW=0.0103PL^3.1293 for females and BW=0.0106PL^3.1251 for males. Monthly changes in gonadosomatic index were analyzed to estimate spawning season. The spawning period ranged from June to November. The size-frequency distribution of eggs suggested that T. japonicus exhibits multiple-spawning during a spawning period. The minimum size of females at maturity was 18.2 cm, while the size at sexual maturity was 25.0 cm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.98-102
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• 2020

We examined the comparative spawning ecology of daggertooth pike conger Mureanesox cinereus and common pike conger M. bagio in the South Sea of Korea from May 2018 to December 2019. In the South Sea of Korea, the mean total length (TL) of M. cinereus was significantly smaller than that of M. bagio. The sex ratios of both species were skewed toward females. The spawning period of M. cinereus was from June to October, while the spawning period of M. bagio was from August to October. The lengths at 50%, 75%, and 97.5% sexual maturity of M. cinereus females were estimated as 54.6 cm, 60.4 cm, and 74.1 cm TL, respectively. It was not possible to estimate lengths at sexual maturity for M. bagio in the South Sea of Korea due to the absence of immature stages.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.983-996
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• 2014

Fish catches by a set net from January 2007 to November 2009 were analyzed to assess fish species composition and seasonal variations in the coast of Gijang, Korea. Over 389 kg fish representing 78 species, 45 families and 17 orders were collected during three years of the study. Dominant species were jack mackerel Trachurus japonicus, anchovy Engraulis japonicus and herring Clupea palasii, and these three species comprised 67.3% of the total number of individuals and 60.7% of the total biomass. Size distribution of the dominant species for jack mackerel, anchovy and herring ranged from 2.2 cm to 22.6 cm, from 2.5 cm to 14.8 cm, from 4.0 cm to 29.0 cm in fork length, respectively. Anchovy was the only species that occurred throughout all seasons in the Gijang coast. Generally, species richness was highest in spring (April to June) when sea temperature began to increase.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.469-482
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• 2013

This study identified problems of the existing ecosystem-based fisheries assessment approach, and suggested new methods for scoring risk and for the estimation of fishery risk index. First, risk scores of zero to two for target and limit reference points for each indicator were replaced by those of zero to three, and the risk scores were calculated from new formulae which were developed in this study. Second, a new method for estimating fishery risk index (FRI) was developed in this study, considering the level of indicators. New method was applied to the Korean large purse seine fishery, large pair trawl fishery and drag net fishery. More precise and detailed risk scores were obtained from the new method, which can explain the risks by the wider range of both risk levels for 'better than target' and 'beyond limit'. The new method for estimating FRI could avoid the basic problem related with duplicated computations of fishery-level indicators, which improved the estimated FRI to be more accurate. Also, a method for estimating variance of FRI using the bootstrap was proposed in this study.

• Journal of Fisheries and Marine Sciences Education
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• v.12 no.1
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• pp.98-121
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• 2000

The Korean fishery encountered a difficulty situation, due to the new regime of the Exclusive Economic Zone (EEZ) and the decreasing fisheries resources in Korean waters. In addition, the coastal areas are deteriorated by industrial wastes, sewage, farming wastes and pollution from aquaculture. In this situation, it is necessary to study the TAC (total allowable catch) - based management system, the development of fishing gears and appropriate fishing methods for stock conservation, and the automation system of fishing gears for improving the efficiency of fisheries. The objective of this study is to look for an appropriate system in marine production and resource management under the new UNCLOS (United National Convention for the Law of the Sea) regime for subjects in fishing gears and methods, production system, and information, and fisheries resources management. The results of this study could be used as scientific information to maintain and develop the Korean fisheries and to establish fisheries policy for the management of fisheries resources in Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.489-497
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• 2021

Climate change is affecting the evolutionary trajectories of individual species and ecological communities, partly through the creation of new species groups. As population shift geographically and temporally as a result of climate change, reproductive interactions between previously isolated species are inevitable and it could potentially lead to invasion, speciation, or even extinction. Four species of abalone, genus Haliotis are present along the Korean coastline and these species are important for commercial and fisheries resources management. In this study, genetic markers for fisheries resources management were discovered based on genomic information, as part of the management of endemic species in response to climate change. Two thousand one hundred and sixty one single nucleotide polymorphisms (SNPs) were discovered using genotyping-by-sequencing (GBS) method. Forty-one SNPs were selected based on their features for species classification. Machine learning analysis using these SNPs makes it possible to differentiate four Haliotis species and hybrids. In conclusion, the proposed machine learning method has potentials for species classification of the genus Haliotis. Our results will provide valuable data for biodiversity conservation and management of abalone population in Korea.

• Fisheries and Aquatic Sciences
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• v.26 no.10
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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.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.777-783
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• 2005

For the sustainable management of marine ecosystem in Masan Bay, we have to assess the carrying capacity and standard of target water quality. In this research, we assume that all pollutants loads are treated in Dukdong sewage treatment plant, then we simulate the physical-biological model for prediction water quality for the achievement of standard water quality. In 2001 year, for the achievement of COD 2.5 mg/L, we need to reduce COD $90\%$, nitrogen $30\%$, phosphate $90\%$ than that of the present value, According to these results, the water quality of sewage treatment plant is required to treat COD 13.5 mg/L, nitrogen 33.3 mg/L, phosphate 6,0 mg/L. If the sewage treatment plant will be expanded much larger in 2011, it will need to be treated in COD 6.6 mg/L, nitrogen 2.5 mg/L, phosphate 5 mg/L for the achievement of water quality standard in COD 2.5 mg/L.

• The Journal of Fisheries Business Administration
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• v.45 no.3
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• pp.19-37
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• 2014

This study is to focus on the status of implementation of bilateral-fishery order based on the Korea-China fisheries agreement and aims to improve fisheries relationship between two countries. Korea-China Fisheries Agreement entered into force in 2001, and serves as a basic framework of the bilateral fisheries order. However, the fishing order between Korea and China has the following limitations. First, it is standstill of joint response for a practical resource management. Second, there are still gaps between the quotas of mutual accord fishing and fishing operation work performance. Third, China's illegal fishing is taking place consistently. Fourth, the effective cooperation between two countries in fisheries is not carried out. Finally, the Korea has faced difficult situations to adhere to a balanced position in the fishery negotiations due to conflicting positions on China and Japan. In order to solve these problems, the fishing order between Korea and China will be able to maintain the competitiveness of Korean fishery sector by reinforcing Korea's fishing sovereignty, Korea and China, based on trust and cooperation, will make efforts to improve bilateral fisheries relations to maximize mutual benefit in fishery sector. Specifically, first, the two countries should strengthen the resources management based on the scientific research and the improvement of imbalance of the mutual agreed fishing in EEZ. Second, Korea has to achieve our targeted performance of fishing operation and establish a joint resources management system between two countries in the provisional measure zone. Third, Korea should implement to collect fisheries information about China fishing vessels which are operating in the EEZ of Korea. Finally, Korea and China should be building up effective governance framework for the establishment of fishing order.