• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.3
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• pp.179-185
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• 2006

In order to efficiently manage the coastal and offshore fishing ground, the applicability of real-time monitering was also investigated through a wide-area network of automatic identification system(AIS). The experiment of efficiently managing coastal and offshore fishing ground with a wide-area network of AIS required, on the headquarter's screen, a synthetic display of vessel information transmitted from three different distant stations. This experiment tested the applicability of real-time monitoring with the shown display. The maximum range of detection of the first station in Busan was 24 nautical miles while those of the second and third stations in Yeosu and Jeju were 26 and 52 nautical miles, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.299-305
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• 1994

Egg distribution and mortality rate for anchovy, Engraulis japonica, and sardine, Sardinops melanosticta, during spring in the southern waters of Korea were estimated using the data from ichthyoplankton surveys conducted from March to April 1991, 1992. Anchovy and sardine eggs were found simultaneously in high density in the southwestern waters of Tsushima Island during March 1991 and late in March${\sim}$early in April 1992. Distribution areas of anchovy and sardine eggs in 1992 was extended to the middle area of the southern waters compared to 1991. Sea surface temperatures in the survey area ranged from 8.6 to $17.8^{\circ}C$. Anchovy and sardine eggs occurred with high densities between $14^{\circ}$ and $15^{\circ}C$. Instantaneous mortality coefficients were estimated to be 0.268/day for anchovy, and 0.132/day for sardine during $4{\sim}15$ March in 1991.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.403-410
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• 2011

Catches, CPUE, fishing season, disc width composition and fishing ground were studied to rebuild skate ray, Raja pulchra resource by the offshore longline fishery in Heuksan-do, Korea. Annual catches and CPUE of skate ray were increased from 2003 to 2010 (CPUE: from 2007 to 2010) continuously. The main fishing season of the skate ray was from December to next May. Disc width at 50% maturity for Raja pulchra by sex were estimated to be 65.83cm, 57.01cm by female and male respectively. The range of disc width was 22.3-112.0cm and the average disc width was 66.9cm, 60.0cm by female and male of Raja pulchra respectively during 2007-2010. Annual average of disc width of female skate ray was decreased from 2007 to 2010. The fishing grounds were formed from the coastal water off Hong-do to the coastal water off Gyeogyeolbiyeol-do, Korea. The center of fishing ground in October was formed in the northwestern coastal water off Gyeogyeolbiyeol-do and separated from that of the other months.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.2
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• pp.116-123
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• 2018

Pacific bluefin tuna (Thunnus orientalis) has been mostly caught by the Korean offshore large purse seine fishery in Korean waters. The annual catch of Pacific bluefin tuna caught by the offshore large purse seine fishery in Korean waters showed less than 1,000 mt until the 1990s except for 1997. The catch sharply increased to 2,401 mt in 2000 and recorded the highest of 2,601 mt in 2003, but the catch has generally decreased with a fluctuation thereafter. The main fishing ground of Pacific bluefin tuna of this fishery is formed around Jeju Island. However, it expanded to the Yellow Sea, the coastal of Busan, and the East Sea, which depends on the migration patterns of Pacific bluefin tuna by season. The CPUE standardization of Pacific bluefin tuna was conducted using Generalized Linear Model (GLM) to assess the proxy of the abundance index. The data used for the GLM were catch (weight), effort (number of hauls), catch ratio of Pacific bluefin tuna, moon phase by year, quarter and area. The standardized CPUE from 2004 to 2011, except for 2003 and 2010, showed a steady trend, and then increased until 2014. The CPUE in 2015 decreased, and in 2016 was higher than that in 2015. The result of GLM suggests that the effect of the catch ratio of Pacific bluefin tuna is the largest factor affecting the nominal CPUE.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.567-582
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• 2014

Coastal fisheries in Korean waters have highly complexity with a variety of fishing gears, and scale of those fisheries is smaller than that of offshore fisheries. As a result, important spawning and nursery grounds for many species of fish has been destroyed. The pragmatic ecosystem-based approach was developed for the assessment of fisheries resources in Korean waters by Zhang et al. (2009; 2010). As for the species risk index (SRI), common squid caught by coastal gillnet in the Uljin region had the highest risk. As for the fisheries risk index (FRI), coastal gillnet in the Uljin coastal waters had the highest risk. For the common squid which had the highest SRI, resources management strategies must be established such as catch prohibition of length and period with TAC. For the coastal gillnet in the Uljin region which had the highest FRI, it is judged to need management plans for conserving biodiversity as reducing the catch of non-target species and discards. Also to protect existing habitat, illegal fishery should be prohibited, and fishing gears should be designed in the environmental-friendly way considering when fishing gears lost.

• Journal of the korean society of oceanography
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• v.37 no.4
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• pp.212-223
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• 2002

Cochlodinium polykrikoides bloom in 1995 was studied with a focus on an unusual coastal environment in the South Sea of Korea. Data on temperature, salinity, and zooplankton biomass during 1965-1998 and nutrients during 1990-1998 and chlorophyll-a during 1995-1998 were used in this study. These data were obtained from the serial oceanographic observations in Korean waters carried out by the National Fisheries Research and Development Institute. In 1995 the C. polykrikoides bloom began in the coastal area around Narodo Island in August and consequently occurred to the whole coastal area of the South and East Seas of Korea. During June-October 1995, the coastal environment was unusual compared with the long-term means during 1965-1998. In June 1995, sea surface temperature was 1-2$^{\circ}C$ warmer than in other years in all coastal areas, while salinity was high only to the east of Jeju Island. In August 1995, a strong coastal front appeared inshore of a line between Jeju and Tsushima Islands. In particular, a strong coastal front which showed the characteristics of upwelling front occurred in the coastal area around Narodo and Sorido Islands, not only because of a strong intrusion of the Tsushima Warm Current but also because of the upwelling of cold bottom water. Salinity was low in the neighboring waters of western side of Jeju Island. Nutrients and chlorophyll-a were high in the inshore area between Narodo and Sorido Islands in 1995 in contrast with the other years and areas. Zooplankton showed an unusually high abundance in the coastal area in October 1995. We conclude that the Tsushima Warm Current strongly influenced the South Sea of Korea in 1995 and created strong upwelling front bordering cold upwelled water in the coastal area around Narodo and Sorido Islands. It leads us that these physical structures introduce the favorable environment for the development of C. polykrikoides blooms. We suggest that C. polykrikoides has a bio-physical tolerance of high shear and stress and prefers frontal and upwelling relaxed areas as its habitat. We also find that nutrients were not supplied to the coastal area from the offshore where a low salinity water mass with high nutrients appeared around Jeju Island. Because the strong upwelling front protect the reach of offshore low saline water mass. The main source of nutrients was the upwelled water mass in the coastal area of Wando-Narodo-Sorido.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.440-448
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• 2013

Estimations on population ecological parameters of the small yellow croaker, Larimichthy polyactis in Korean waters, were calculated using catch data based on coastal and offshore drift gillnet fishery and biological data from 2010 to 2012. The population ecological parameters included survival rate, instantaneous coefficient of natural and fishing mortality and age/length at first capture. The survival rate (S) of the small yellow croaker was estimated to be 0.20 from catch curve method. The instantaneous coefficient of natural mortality (M) was estimated to be 0.46/year with Alverson and Carney method. The instantaneous coefficient of total mortality (Z) was 1.611/year, used to be transformed the survival rate and the instantaneous coefficient of fishing mortality (F) were 1.153/year. The length at first capture ($L_c$) was 19.1cm by Pauly method, and the age at first capture ($t_c$) was 1.303 years of the small yellow croaker by the coastal and offshore drift gillnet fishery.

• The Journal of Fisheries Business Administration
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• v.25 no.1
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• pp.37-59
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• 1994

Many studies to cope with the present problems of Korean coastal and offshore fisheries has been performed, but these were done partly in necessities and general studies for Korean inshore and offshore fisheries are in early stage. Most of these studies adopted analytical way of approach for each fishery individually and they could not reflect the effect of correlated interaction among fisheries on the several common species/stocks, and thus optimal effort allocation was impossible. To consider general fisheries and optimal effort allocation among competing mixed species, a linear programming (LP) approach is applied in this study and introduced into 16 important inshore and offshore fisheries with 13 constraining species which were chosen by annual yield order. This study is not based on the biological interaction among species (i.e., prey - predator system) but the technological interaction between species and fishing efforts. For the application of LP model in these fisheries, the standardization of fishing efforts through different fishing gears could not be successful and a new way of effort standardization through CPUE for vessel tonnage was originated. Total standardized fishing effort on a particular species i, Ei, is computed as the linear summation of standardized fishing effort generated by each fishery j. That is, (equation omitted) where $f_{j}$ is the total vessel tonnage of fishery j and aij is the coefficients contributing to the standardized fishing effort per ton for species i taken in fishery j. The total fishing effort level on species i due to both directed fishing and by - catch can thus be accounted in the aij's. Optimal effort allocation among the j fisheries may be considered a minimizing problem (minimize $\Sigma$ $f_{j}$), subject to the constraints that standardized fishing effort levels on particular species are maintained at, above, and below certain predefined levels. Fishing effort goals for individual species can be based on various biological and/or economic criteria, i.e., fishing effort level generating maximum sustainable yield and/or maximum economic yield. But in this study the $F_{0.1}$ criteria which was accepted as an approximate level for $F_{mey}$ by Outland and Boerema's (1973) study. The findings of this study are, (1) LP model can be applied to the Korean inshore and offshore fisheries giobally. (2) Through a new way of combining multiple different fisheries' efforts for a particular species together generating standardized fishing effort, Schaefer curve could be applied to the complex system successfully. (3) The results of this study for total reduction scale were mostly the same as those of prior studies, but different much from the individual scales of reduction. This study showed the necessities for exploitation of more concrete parameters to put into consideration of profitability of fisheries and social factors, and this model can be modified according to the actual constraints. Also, considering the age structure of stocks, this model can be developed into better one for better fisheries management.ent.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.527-534
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• 2015

The twenty six specimens of leptocephali (15.8-32.6 mm TL) of the family Congridae, collected from southeastern waters offshore of Jeju Island during August 2014, and were identified by means of morphology and genetics. Those specimens were identified as belonging to the family Congridae based on various combinations of morphological characters. An analysis of the partial 12S rRNA sequences (886 base pairs) of mitochondrial DNA showed that our specimens must be Gnathophis nystromi, because their sequences were concordant with those of G. nystromi adult (genetic distance= 0.001), furthermore their total myomeres being consistent with those of G. nystromi adult. Catch rates of G. nystromi leptocephali were higher in the offshore regions than coastal regions of Jeju Island. The smallest leptocephali (< 20 mm TL) were collected offshore from Jeju Island. We hypothesize that one of the spawning grounds of G. nystromi is located offshore in the Jeju Island. In conclusion, the hatched preleptocephali of G. nystromi might have been transported from offshore near Jeju Island to the Korea Strait by the Kuroshio Current and Tsushima Warm Current.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.15 no.2
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• pp.77-82
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• 1979

It is said that anchovy of 6 to 7 em in body length is the most suitable for the live bait in skipjack pole and line fishing, and it must be held in a creel for more than 7 days so as to be transported from the holding ground to the fishing ground, kept in the small bait hold in a fishing boat. To hold the live bait anchovy, holding creel should be settled in calm waters, and then it is necessary to investigate the appearance of the available resource in the south-eastern coastal waters of Korea where the creel can be settled. The authors investigated the app~arance of the available resource in the waters, and the following results are found. 1. The available resource appears more and the fishing season is longer than in the offshore, rather than in the inshore. 2. The available resource arc caught in the offshore with the passing of time into winter, and they are caught merely in the offshore side in December. 3. The available resource could be secured from July to December, somewhere in the south-eastern coastal waiers of Korea, if the holding ground were removed appropriately.