• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.411-416
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• 2011

We investigated the nutritional status of the melania snail (Semisulcospira gottschei) using RNA/DNA ratios to evaluate the effect of feeding conditions (artificial versus natural) on the reaction times of the snails in a time course following starvation. In the short experiments (48 h), the RNA/DNA ratios of the artificial feeding groups were significantly higher than those of the natural groups. While two RNA/DNA ratio peaks were observed in the artificial food group during daytime, the natural food group showed a higher ratio at night. Under starvation conditions, the RNA content decreased whereas the DNA content was constant. The RNA/DNA ratios of the freshwater snail in both groups dramatically decreased after starvation and remained constant until the end of the experiment. We verified that the RNA/DNA ratio serves as an index of nutritional condition with respect to the effect of dietary differences. These results are important for understanding optimized aquaculture rearing conditions for this important commercial freshwater snail.

• 수산경영론집
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• 제48권1호
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• pp.17-29
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• 2017

The primary purpose of this paper is to analyze the membership of fishing community. In order to become a member of fishing community, some conditions are needed both the member of local fisheries cooperatives and resident of fishing village. Generally, many fishing communities have additional conditions such as to be a member of fishing community that is a minimum term of residence, an entrance fee, fishing abilities. These additional conditions play a critical role in making a relationship, building trust and enhancing fairness. However, the setting of excessive additional conditions make it possible to obstruct growth of fishing community.

• 수산경영론집
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• 제32권2호
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• pp.51-72
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• 2001

This study intends to review the development of Squid Angling Fisheries of Korea and Japan and subsequent changes in the fisheries regime as well as management conditions and to examine reorganization directions. Although catches and productivity are all increasing in Korea and Japan as the squid resource in the East Sea is improving, the number of fishing vessels and the conditions of fisheries management are showing a symmetrical relationship. The former is increasing in Korea and decreasing in Japan while the latter is aggravating in Korea and rather stable in Japan. And while the competition between the two countries for more fishing grounds and catches are not that serious since the resource is relatively increasing, the catch and price competition with other domestic fisheries is a more significant problem. Furthermore, even though light restriction is implemented in both countries in order to suppress over-competition, it is adopted as a means to curtail management costs and block over-investment rather than to adjust international or inter-fisheries circumstances. Japan has been implementing the TAC system on squid resources since 1998. However, it has a different meaning than as a resource management method in its original sense because it is based on the highest catch level of the past and takes into consideration the fishermen's management conditions. In case of Korea, it is necessary to establish a plan to strengthen its fisheries management competence to address its shrinking catch in the Japanese waters. The developments mentioned so far have appeared amidst the increase of squid resources, and if such conditions disappear, problems such as international allocation of catches and fishing seasons, access to fishing grounds, and domestic conflicts among different fisheries will emerge.

• 수산해양기술연구
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• 제47권2호
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• pp.108-117
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• 2011

In order to offer data about fisheries resources management and prediction of catch on large purse seine fisheries, the fluctuation of the fisheries condition and distributions of fishing ground for mackerel were analysed with monthly catch data for 1990.2009. The overall catch has decreased to about 70% since 1997, with approximately 70% of the mackerel (Scomber japonicus) catch and monthly fluctuations showing a similar pattern. Monthly distribution of fishing ground is like distribution of mackerel in large purse seine fishery. The main fishing grounds are near Jeju Island and the Yellow sea with the main fishing season existing between October to December. The catches fluctuations and distribution of fishing ground were related to the effect of regime shifts. Therefore, in order to prediction of catch on large purse seine fisheries should be studied these relationships.

• 한국수산과학회지
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• 제36권4호
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• pp.417-429
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• 2003

Abnormal oceanic conditions associated with the passage of typhoons are examined using hydrographic and satellite data 1990-2002. During the passage period of typhoons in the Korean waters, an abrupt decrease of sea surface temperature (SST) in range of 5 to $8^{\circ}C$ was observed. The areas of SST decrease were an order of 100-200 km, and the low SST lasted about 15-25 days after passage of typhoon. After passage of typhoon, the water temperatures in the surface mixed layer of 30 m show negative anomalies for quite a long period. In addition, stratification parameters were substantially decreased and chlorophyll a density was rapidly increased.

• 수산경영론집
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• 제21권1호
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• pp.57-96
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• 1990

• Fisheries and Aquatic Sciences
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• 제5권2호
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• pp.141-143
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• 2002

The treatment efficacy of oral administration of praziquantel against the blood-sucking monogenean Microcotyle sebastis under the commercial rockfish-culture conditions was evaluated. The quantity of praziquantel added to the food was calculated so that the amount of praziquantel ingested daily by fish was 200mg or 400mg/kg body weight (bw). The fish were fed a moist-pelleted fish meal supplemented with praziquantel at an rate of 0 (control), 200 or 400 mg of praziquantel per kg bw, respectively, for 3 times at an interval of 24 h. On 1 day to 8 days after the treatment, 10 fish were taken randomly from each net-pen daily (80 fish in each group in total), and the efficacy of each treatment was confirmed. Abundance of worms were significantly reduced in groups fed praziquantel-supplemented diets. The results clearly demonstrated that feeding the praziquantel-supplemented diet was effective for controlling M. sebastis infestation in practical commercial rockfish-culture systems without imposing any handling stress.

• 수산해양기술연구
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• 제51권4호
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• pp.475-483
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• 2015

The marine microalgae Isochrysis galbana was cultured under various light-emitting diode (LED) light conditions with different wavelengths to examine changes in growth and in amino acid and fatty acid profiles. The culture conditions for the microalgae were Conway medium, salinity of 33 psu, temperature of $24^{\circ}C$, and a 16/8 h light/dark photoperiod. Six light sources, including 5 units of 180W LED lamps (peak wavelength: blue [LB] 470 nm; green [LG] 525 nm; yellow [LY] 595 nm; red [LR] 636 nm; white [LW] 442 nm) and 1 unit of a 175W metal halide (MH) lamp, were used for the experiment. The dry cell weights ($gL^{-1}$) of I. galbana under different light conditions were in the order of LW>LB${\geq}$MH>LR>LG>LY. Levels of essential amino acids were revealed to be significantly higher under LW, LG, and MH than under the other wavelengths (P<0.05). The fatty acid, unsaturated fatty acid, and DHA contents of I. galbana were higher under MH, LW, and LG. In addition, the carotenoid content was higher under MH, LW, and LG than under the other wavelengths (P<0.05). The fucoxanthin content was highest under MH (0.28%) and lowest under LY (0.2%), and it was 0.26% under LW and LG. The results indicate that the combined use of LW and LG is effective when using LED lamps for I. galbana cultivation.

• 수산경영론집
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• 제42권1호
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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.

• 한국수산과학회지
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• 제47권4호
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• pp.419-423
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• 2014

We consider changes in the fishing ground of the small yellow croaker Larimichthys polyactis and discuss their utility in predicting fishing conditions for this species. The fishing ground, which having been formed around Jeju Island since the 1970s, is dominated by the Yellow Sea Bottom Cold Water (YSBCW), and variation in its southward expansion from the Yellow Sea is the single most key environmental factor affecting the L. polyactis catch. When the YSBCW showed strong expansion and the fishing ground shifted to the west and southwest of Jeju Island, as occurred in the late 1980s, late 1990s, and early 2000s, the L. polyactis catch was low; conversely, when expansion was weak, as in the early 1990s and late 2000s, the L. polyactis catch was high. This relationship was statistically significant and should be useful in predicting fishing conditions for L. polyactis.