• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.654-658
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• 2014

We report the first identification of a spawning ground of the blackfin flounder Glyptocephlaus stelleri near the Wangdol-cho sea mountains, located in the southern East Sea. Eggs and larval fish of G. stelleri were collected during April and June, 2014, when an abundance of eggs was found in the southern area of Wangdol-cho. Our findings suggest that G. stelleri prefers to spawn in the vicinity of the off-shore sea mountains, where the temperature is between 10 and $12^{\circ}C$ and the water depth is 100 m, rather than inshore.

• The Journal of Fisheries Business Administration
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• v.42 no.1
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• pp.71-83
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• 2011

An ecosystem-based fisheries management (EBFM) approach becomes more important as an alternative management method for a sustainable development of fisheries domestically and internationally. Many methods of applying a practical EBFM to fisheries management have been investigated, and considerable attention has been given to developing effective indicators of the present status of and changes in ecosystems and putting them to practical use. Among ecosystem indicators, developing socioeconomic indicators for EBFM is particularly important. This is because socioeconomic factors have direct effects on ecosystems, and ecosystems have direct effects on socioeconomic factors. Therefore, it is imperative that socioeconomic indicators are developed and evaluated in order to predict changes in ecosystems and to provide advice for effective fisheries management. This study is aimed to develop socioeconomic indicators which can be combined with biological and ecological indicators, in order to conduct the ecosystem-based fisheries assessment. In terms of socioeconomic indicators, five socioeconomic criteria were considered as important attributes of socioeconomic changes. These criteria include economical production, business conditions, income, market, and employment indicators. For evaluation of newly developed socioeconomic indicators, the Traffic Light System (TLS) method was used. In addition, on the basis of the application of developed indicators to the Korean large purse seine fishery, the socioeconomic conditions of the fishery and the usefulness of the indicators were evaluated and management implications were discussed.

• 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.46 no.5
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• pp.534-539
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• 2013

To secure the biological safety of live fish and shellfish for raw consumption, the germicidal effects of electrolyzed seawater were evaluated. Upon direct exposure to electrolyzed seawater, coliform group bacteria were killed and decreased to undetectable levels after 1 day. The physicochemical characteristics of the seawater were stable during the test period. A byproduct of chlorine disinfection, trihalomethane, was not generated by the electrolysis of seawater. Vibrio parahaemolyticus infection in a live fish was effectively resolved by electrolyzed seawater and became undetectable after 12-36 h of treatment. Bioaccumulation of coliform group and fecal coliform bacteria in live oysters Crassostrea gigas was removed within 18 h of treatment. This study demonstrated that electrolyzed seawater is an effective and safe germicidal agent for the traditional retail market and can help to prevent outbreaks of foodborne disease associated with the consumption of raw fish and shellfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.513-519
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• 2013

The fishing industry in Europe has faced environmental, economic, and social challenges. Since the early 2000s, a key tool in addressing these challenges has been information and communication technology (ICT), which has helped to modernize fishery systems in European Union (EU) countries. The ICT used in EU fisheries can be categorized broadly as 1) macro-technologies such as satellite and other remote sensing technologies in combination with geographical information systems, 2) micro-technologies adapted for fishing vessels such as echo sounders, ship navigation devices, and mobile communication devices to connect fishermen and consumers, and 3) onshore micro-technologies related to internet technology and mobile devices. The European Monitoring Center on Change has used ICT to effectively manage fisheries bio-resources. This use of ICT has contributed to the development of sustainable and competent fisheries in the 2000s, even though the knowledge-sharing practices involved are contrary to the long tradition of autonomy within the fishery industry.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.1
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• pp.50-57
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• 2014

The performance of five kind adsorbents, which can reduce nitrogen oxide (NOx) from the diesel engine occupying 85% of the fishing boat, was carried out and the emission reduction filter was manufactured and evaluated in the adsorption efficiency of the emission gas for 240 KW diesel portable generator. As a NOx emission filter made of mordenite which has an excellent cation exchange capacity was manufactured by ball type adsorbents having excellent specific surface area. The adsorption efficiency of mordenite material applying the emission reduction filter began to show up at the operating time 10 minutes in comparison with the activated carbon and zeolite materials, and it was exposed to continue until 100% capability with passing by 20 minutes. So the adsorption efficiency of the NOx reduction filter consistently maintained at the averaged 80%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.261-269
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• 2013

The age and growth of the Pacific cod, Gadus macrocephalus were investigated using left sagittal otoliths of 682 individuals collected in the West Sea of Korea from January to December 2007. The seasonal changes in the ratio of an opaque zone to interval between annular rings revealed that the narrow translucent parts of the otolith were annual growth rings formed between February and March once a year. The spawning period was December to January and therefore the duration from fertilization to the complete formation of the opaque zone became thirteen months. From the parameters calculated using the average length when the year ring was formed, the estimated von Bertalanffy growth equations were $L_t=100.0(1-e^{-0.1640(t+0.5247)})$ for females and $L_t=64.6(1-e^{-0.3335 (t+0.3342)})$ for males when is total length in age t.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.648-656
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• 2016

The age and growth of jack mackerel Trachurus japonicus caught by large purse seine fishery were studied during August 2004 and May 2005. Otoliths of 472 fish were observed under reflected light, and translucent zones made on the post-rostrum axis were regarded as annual marks. Monthly changes in the marginal index indicated that the translucent zone was formed once a year, mainly in March-April, which was coincident with the peak spawning time of jack mackerel. The estimated ages were 0-6 years, corresponding to a fork length (FL) range of 13 to 38 cm. Most obtained individuals were 2-year-old fish, followed by 1-year-old fish. The mean fork length at age from otolith reading (sex combined) was applied to the von Bertalanffy equation and growth parameters were estimated: L_∞ = 38.29 cm FL, k = 0.31 years⁻¹, t₀ = −0.81 years.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.788-798
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• 2017

Antarctic krill Euphausia superba are important components of the Antarctic marine ecosystem both economically and ecologically; to manage this species effectively, their distribution and abundance must be understood. Using the Kwang Ja-Ho (3,012 tonnage), a commercial fishing vessel, we conducted acoustic surveys during April 13-24, 2016, to estimate the distribution and population size of krill around the South Shetland Islands of the Antarctic Continent, We used acoustic techniques based on the dB-difference, a method used mainly to classify of marine species. We found that Antarctic krill were present in numbers over 99% at six survey stations, with the exception of Station 3, where we only found Electrona carlsbergi. There was no difference in cell size due to frequency differences, but echo signals differed between species: 4.7-12.0 dB for Antarctic krill, and -4.1~0 dB for Electrona carlsbergi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.305-312
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• 2018

This study was carried out to investigate euphausiid abundance in an acoustic survey from March 2010 to July 2010 to suggest reasonable usage and management of the euphausiid Euphausia pacifica in the coastal area of Guryongpo Pohang. The acoustic data were analyzed by the 2-frequency difference method and the distorted wave born approximation acoustical theoretical model, which is used for organisms of weak target strength with small scatter, such as euphausiid scatter, among other marine organisms. The distribution and monthly density of euphausiids were estimated in the survey area. The results show that the volume back scattering strength frequency difference for euphausiid was 13.91-7.6 dB, and their monthly averag density was $28.2g/m^2$.