• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.283-291
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• 2014

This study assessed dominant fish species, and the characteristics and spatio-temporal distribution of fish schools using acoustic and catch data in the marine ranching area (MRA) of Yeosu in July and August 2013. Acoustic data were collected using a 200-kHz dual beam transducer, and catch data were analyzed through auction data generated by a set net installed in the MRA. More fish schools were detected by acoustic methods in July than in August. The temporal distribution of fish schools differed between July and August, but, many schools demonstrated a high mean volume scattering strength (SV) around artificial reefs. Additionally, the characteristics of fish schools detected by echograms and the species caught by set nets differed between July and August. The dominant fish species were Engraulis japonicus, Pampus argenteus, Scomberomorus niphonius, and Pampus echinogaster in July, and approximately 85% of the catch in August consisted of Scomberomorus niphonius. Therefore, hydro-acoustic tools are useful for estimating fish school characteristics in large areas over a short period. To determine species, it is important to conduct net sampling surveys during the acoustic surveys. However, if a database of fish school characteristics organized by species is constructed through continuous study, it could be possible to identify fish species through acoustic methods alone.

• Journal of Nutrition and Health
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• v.29 no.1
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• pp.32-40
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• 1996

To investigate the effect of dietary docosahexaenoic acid(DHA) and environmental enrichment on brain fatty acid composition and acetylcholinesterase(AChE) activity, two groups of was fed isocaloric diets containing 10 or 12% dietary lipids for 7 weeks. A third group was fed 10% (w/w) dietary lipids with supplemented 2% DHA-rich fish oil. Each diet group was housed either in a stainless steel cage individually or in a large enriched cage with toys where 7 rats were kept together. The fatty acid composition of plasma and brain was significantly affected by dietary lipid composition but not by environmental enrichment. Fish oil supplementation significanlty decreased plasma levels of monounsaturated fatty acids(MUFA) and increased polyunsaturated fatty acids(PUFA). Fish oil supplemented groups also maintained lower plasma n-6 fatty acids and higher n-3 fatty acids levels than unsupplemented groups. The fish oil supplementation significantly decreased arachidonic acid and increased eicosapentaenic, docosapentaenoic acids, and DHA in brain fatty acid composition. In addition, brain DHA level in supplemented groups tended higher than the unsupplemented. Brain, AChE activity significantly increased by the environmental enrichment but not by the fish oil supplementation. These finding suggest that the 2% fish oil (0.57% DHA & 0.31% EPA, per diet weigth) supplementation is enough to accumulate n-3 fatty acids and to change the n-6 n-3 ratio in brain and environmental enrichment might promote the learning ability.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.55-61
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• 2011

Fish larvae were collected monthly with an ichthyoplankton net from 18 stations (including four stations located in eelgrass beds) in Gamak Bay and Yeoja Bay, southern Korea, in 2007. In total, 33 species of fish larvae were collected, of which Engraulis japonicus (48.5%), Tridentiger trigonocephalus (21.5%), and Omobranchus elegans (9.2%) were dominant. Dominant species varied seasonally: Hexagrammos otakii during December and January, Pholis nebulosa during January and March, Acanthogobius flavimanus in April, T. trigonocephalus in May, E. japonicus during June, July, September, and November, and Sillago japonica in August. Dominant species also differed between sites inside and outside the bays. Leiognathus nuchalis, O. elegans, and T. trigonocephalus were more abundant inside, while H. otakii was more abundant outside. From cluster analysis, three groups were identified according to sampling months (January-April, May-September, and October-December) and two groups according to station (inside and outside bays). The occurrence of small larvae of almost all major fish species indicated that the bays were used as spawning and nursery grounds. An exception was Lateolabrax japonicus, whose specimens were relatively large (>19 mm TL), suggesting that this fish may spawn offshore, with its juveniles approaching the bays with growth.

• Journal of Plant Biotechnology
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• v.37 no.3
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• pp.269-274
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• 2010

As the capture fishing industry has declined, the aquaculture industry has become an important source of seafood. With this tendency all fish farming will be performed by large-scale farms where the fish are cultivated in much high density and as a result the incidence of infectious diseases increases. Therefore, vaccination has become an increasingly important part of aquaculture as a cost effective method of controlling various diseases. The early fish vaccines were the formalin inactivated bacteria or virus cultures, which were administered by either immersion or injection. Recombinant DNA biotechnology allowed us to develop orally administrated DNA and recombinant vaccines. In terms of the manufacturing process and cost, Lemna and Spirodela is the most efficient and reliable plant expression system for the production of edible vaccine.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.678-683
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• 1996

The purpose of this study was to elucidate characteristics of hydrolysates from file-fish flesh with various proteases. File-fish flesh was chopped, homogenized with water, and hydrolysed by 8 different kinds of commercially available protease. High production of peptide was observed in bromelain and neutrase treatment. On the other hand, large amount of free amino acid was observed in esp/sav and pronase treatment. Neutrase and pancreatin hydrolysate contained large amount of 5'-GMP. Organoleptic studies showed that the bromelain, esp/sav and protease hydrolysate had strong bitter taste, while pronase and esp/sav hydrolysate had strong umami taste. From these results, pronase was found to be suitable enzyme for producing file-fish hydrolysate.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.239-248
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• 2003

This paper was conducted as an attempt in order to construct the data bank of target strength for acoustic estimation of fish length in the coastal waters of Korea. The fish length dependence of acoustic target strength for 13 large yellow croakers (Pseudosciaena crocea) at 75 kHz was investigated and the prediction of the target strength by using the Kirchhoff-Ray Mode model (KRM model) was compared with target strength measurements. The results obtained are summarized as follows; 1. In the averaged target strength pattern for 13 large yellow croakers the maximum target strength was -35.13 dB at $-13.35^{\circ}$ on a tilted angle. 2. The relationship between fork length(L, cm) and averaged target strength(TS, dB) was expressed as follows; TS=23. 76log (L) -73.45 (r=0.47) TS=20log(L) -67.35 From this result, the conversion coefficient was -73.45 dB and 6.1 dB lower than the coefficient -67.35 dB where the value of the slope of the regression equation is forced to be 20. 3. Averaged target strength and a length conversion coefficient derived from a target strength histogram for 13 large yellow croakers of mean length 25.59 cm were -41.23 dB, -69.72 dB, respectively. 4. In the range of $$2;{\ll} L (fish length /{\lambda}(wave length);{\ll}40$$, the prediction of the averaged target strength by the KRM model increased gradually with the increasing of $L/{\lambda}$ and was lower than the measured target strength.

• The Journal of Fisheries Business Administration
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• v.36 no.1 s.67
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• pp.139-153
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• 2005

Marine fish aquaculture has been introduced on the East sea since 1964. The production volume of the marine aquaculture has been increasing drastically since 1990 with the technological improvements and the introduction of new species. However, the increasing costs of feed, seedlings and medical supplies and the decreasing prices due to the increase in the imports and domestic production have decreased the profits in the aquaculture business. Futhermore, the damage from the natural disasters such as red tides and typhoons has accelerated the exit from the business. Even though managing abilities to overcome the business crisis caused by the above factors are required, business managers based on the small scale family businesses do not have enough managing abilities to deal with the difficulties in the business. On the other hand, advanced countries in the marine aquaculture such as Norway have reached the stage where the managing abilities of marine aquaculture are similar to those in the manufacturing industry. And the number of large scale aquaculture farms with developed technologies and advanced marketing strategies in those countries is increasing. Considering that the marine aquaculture in Japan under the similar fishery systems of Korea has developed the state-of-the-art management skills or lead to large scale management, it is difficult to expect the decrease in the production costs under the small scale family business in Korea and this will lead to the decreasing competitive advantage over the imported seafood. Therefore marine aquaculture in Korea needs to increase the economy of scale to acquire the competitive advantage. This study addresses the possibility of introducing the large scale aquaculture system in Korea by analysing the factors and process of leading to large scale businesses in the aquaculture in Japan.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.160-167
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• 1998

Proximate composition, cholesterol (CHOL) and $\alpha-tocopherol$ ($\alpha-Toc$) content of seventy-two species of fish muscle (sea water fish, 59 species; fresh water fish, 13 species), which caught off Tongyeong coast of the Southern Sea ( Nam-Hae) and caught Kyeongho river, Sancheong, Korea, were determined. Lipid content was ranked from $0.53\%$ to $20.4\%$ and was high in the following order; mid-surface dwelling and migratory fish ($6.09{\pm}4.25\%$) > fresh water fish ($4.40{\pm}5.90\%$) > coastal and reep dwelling fish ($3.41{\pm}2.68\%$) > demersal fish ($2.12{\pm}2.41\%$). There was a negative correlation between the lipid and moisture content in all fish groups (p< 0.001). Protein was approximately $17\~18\%$ in all fish group, and no correlation was between the protein and moisture content in all but the demersal fish, which there was a negative correlation between both contents. Ash content was almost constant in all fish, accounting for $1\~2\%$, Cholesterol (CHOL) content was shown a great difference according to the fish species from 6.7 mg/100 g muscle (grass fish) to 249 mg/100 g (eel) and there was a positive correlation between the lipid and CHOL content. $\alpha-Toc$ content was less than 3 mg/100 g muscle in all fish, except that of eel (4.1 mg/100 g) and was relatively rich in the fish species contained a large amount of lipid.

• Ocean and Polar Research
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• v.30 no.1
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• pp.79-87
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• 2008

Hydroacoustic technique was used to analyze spatiotemporal stability and distribution of demersal fish aggregations in the coastal region to overcome some limitations of the existing methods such as net and diving. The survey was carried out in the Baekeum Bay on the south coast of Korea in January 2007. The bottom depth in the study site ranges from 7 to 25 m. In order to outline aggregations of demersal fish initial scanning using 200 kHz split-beam transducer was randomly conducted over the large area. Having detected fish aggregation in the specific region, intensive acoustic survey of irregular star pattern was carried out along 14 transects across the area in question. The results of the acoustic survey show that all demersal fish aggregations are concentrated about 5 m from sea bottom having a slight slope and remain steady with no spatial or temporal variations during acoustic survey. The hydroacoustic method used in this study offers a new approach to understand vertical and horizontal distribution, spatiotemporal stability, and biomass estimate of demersal fish aggregations in coastal regions. Additionally, the number of individual fish estimated from in situ acoustic target strength data can be used to understand the standing stock of demersal fish aggregation.

• Journal of fish pathology
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• v.13 no.1
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• pp.61-66
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• 2000

A method was developed for concentrating fish pathogenic virus from sea water using membrane ultrafiltration system and centricon. The method consists of passing large volumes (Ca. 20 liter) of sea water through ultrafiltration (PAN) filter followed by cross-flow filtration method and centrifugation use the centricon (Plus-20). This procedure permitted the processing of 20 liter of sea water which resulted in a 20,000-fold reduction in the volume of water and greater than 90% recovery of the seeded MABV.