• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.4
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• pp.27-40
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• 2002

The circulation of sea water was simulated by two dimensional tide model using the main four tidal components and permanent current driven by inflow/outflow across open boundaries. According to the residt of tide model, the maximum speed of eastward flow on the Cheju Strait is twice higher than that of westward flow. According to the result of permanent current, the flow of permanent current showing semi-circle pattern in the southern part of Kojedo was due to variation of topography. According to the result of circulation model in the Cheju Strait, eastward flow entering in the southern waters from the Yellow Sea of Korea were dominant, but outflows westward were weak. These results suggest that it was difficult to move for suspended particulate matter into the Yellow sea from the southern waters through Cheju Strait.

• Korean Journal of Ichthyology
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• v.34 no.4
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• pp.225-230
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• 2022

The single postlarval specimen (7.53 mm in standard length) of Thalassoma quinquevittatum (Lay & Bennett, 1839), belongs to the family Labridae, was collected by a bongo net from the southern coastal waters of Jeju-do Island, Korea in November 2020. T. quinquevittatum has a deeply curved dorsal contour before the dorsal fin, the oval eyes, and no melanophores throughout the body. While T. amblycephalum has a slightly curved dorsal contour before the center of the dorsal fin, the circular eyes, and few melanophores on the body. A molecular analysis based on 548 base pairs sequences in the mitochondrial DNA cytochrome c oxidase subunit I region shows that the specimen was closely matched to adult T. quinquevittatum (K2P distance=0.002-0.005). We report the first record of T. quinquevittatum in Korean waters, and suggest its new Korean name "Da-seot-jul-saek-dong-nol-rae-gi".

• Korean Journal of Ichthyology
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• v.35 no.1
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• pp.57-63
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• 2023

Four individuals of Lipolagus ochotensis larvae (13.4~21.3 mm SL), belong to the family Bathylagidae, were collected by a Bongo net from the southern waters off Jejudo Island, Korea in February to March 2018. L. ochotensis is characterized by a elongated and compressed body, the eye stalks, series of melanophores on posterior of body, dorsal fin origin above the middle of the body. A molecular analysis based on 625 base pairs sequences in the mitochondrial DNA cytochrome c oxidase subunit I region shows that specimens were closely matched to adult L. ochotensis (genetic distance=0.024). We report the first record of family Bathylagidae, genus Lipolagus, L. ochotensis in Korean waters, and suggest their new Korean names, "Sim-hae-bing-eo-gwa", "Geom-eun-bing-eo-sok", and "Geom-eun-bbyam-bing-eo", respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.4
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• pp.399-406
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• 2023

This study presents an analysis of bycatch data concerning Pacific white-sided dolphins (Lagenorhynchus obliquidens) along the Korean coast from 2016 to 2021. A total of 503 bycatches were examined, encompassing data on year, month, body length, sex, latitude (N), longitude (E), and fishing gear. Bycatch was the most frequent in waters with a longitude of less than 130°E, particularly in the southern coastal region at a latitude of 35.5°N, with a higher likelihood of bycatch in lower latitudes. Since 2017, a decreasing trend in bycatches has been observed. The sex distribution of bycaught dolphins showed a predominance of males (40%), followed by females (31%), with an unclassified category at 29%, though no statistically significant differences were found (p > 0.05). Seasonal analysis indicated that bycatch predominantly occurred during the winter months, with significant monthly variations (p < 0.01). Pacific white-sided dolphins were primarily ensnared in gill nets and, to a lesser extent, in stationary nets. Statistical analysis by gear type revealed a significant preference for gill nets (p < 0.001). Considering body length composition in relation to latitude, it is suggested that Pacific white-sided dolphins may utilize the southern waters of the East Sea as a potential nursery ground, though this was not confirmed at a significant level, emphasizing the need for further in-depth monitoring and ecological investigations. Given that there are approximately 27 different types of gill nets associated with the majority of bycatches, more detailed research is warranted to divide these gear types into finer subcategories for estimating bycatch relationships, ultimately leading to the development of effective conservation and management strategies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.535-548
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• 1994

Community structures and fish densit were investigated on three different types of artificial reefs, dice, turtle artificial reef and tubes, constructed in the Korean waters. Variations of fish fauna according to type of artificial reef and the proper artificial reef in each area for optimizing harvest were discussed. Fish were captured by trammel gill net during May, June, September and November, 1988 and both identified and counted. Fourty-five fish species were found in the artificial reefs. Of these, Sebastes spp., Hexagrammos otakii, Pleuronectidae, Navodon modestus and Stephanolepis cirrhifer showed high occurrence-frequency. The dominant species groups were coastal settlement, demersal or rock fishes such as Pleuronectidae, Rajiformes, Stephanolepis cirrhifer, Navodon modestus, Hexagrammos otakii and Sebastes spp. in all of the Artificial reefs except the oceanic area of southern waters. Scomber japonicus was predominant in the oceanic area of southern waters. Composition of demersal, rock and pelagic fishes were different depending on the types of artificial reef. Dice artificial reefs were occupied by rock fish, on the other hand turtle artificial reefs were dominated by dermersal fish. Fish density was high at the dice artificial reef in all survey areas except the middle area of Eastern waters, with high fish density evident in the Tube artificial reef. Fish community structures were remarkably different between Dice and Turtle artificial reefs. The Tube artificial reef showed intermediate characteristics between the above two types of artificial reefs. The coastal areas of Southern waters and the middle and southern areas of Western waters revealed similar fish fauna. Results from the oceanic areas of Southern waters were well associated with the middle and southern areas of Eastern waters.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.179-195
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• 2004

The trophic state of the coastal waters of the southern part of Korea was assessed using biogeochemical data obtained from the National Marine Environmental Monitoring Program conducted by the National Fisheries Research and Development Institute for six years. The trophic state of different areas, analyzed by non-metric multi-dimensional scaling (MDS) analysis, could divide the areas into three groups. Masan Bay, with suboxic water masses and/or the highest concentrations of dissolved inorganic nitrogen and phosphorus occurred, was assessed as being in a hypertrophic state. Ulsan Bay, Onsan Bay, Busan and Jinhae Bay, located near strong point sources, were in a eutrophic state. Other areas, including Tongyong, Yosu, Mokpo and Jeju island, were evaluated as being in a mesotrophic state. During 1997 to 2002, the average values of excess nitrogen, which is the difference between the measured dissolved inorganic nitrogen (DIN) and the corrected DIN using the Redfield ratio, were positive at Ulsan, Onsan, and Busan, where there were inflows from polluted rivers. In contrast, those were negative values in Haengam Bay, Gwangyang Bay and nearby Yosu. This suggests that the limiting element for phytoplankton growth differed among sites. The time series data of excess nitrogen showed gradual decrease over time in the hypertrophic waters, but the opposite trend in the mesotrophic waters. This indicated that the ratio of nitrogen to phosphate varied according to the trophic state of the coastal waters. The enrichment of organic matter in sediment in eutrophic waters would disturb the normal pattern of biogeochemical cycling of nitrogen and phosphate. In order to assess the condition of the coastal environment, the benthic boundary layer should be considered.

• Ocean and Polar Research
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• v.34 no.2
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• pp.111-123
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• 2012

To understand the phytoplankton community in the eastern part of the Yellow Sea (EYS), in the summer, field survey was conducted at 25 stations in June 2009, and water samples were analyzed using a epifluorescence microscopy, flow cytometry and HPLC method. The EYS could be divided into four areas by a cluster analysis, using phytoplankton group abundances: coastal mixing area, Anma-do area, transition water, and the central Yellow Sea. In the coastal mixing area, water column was well mixed vertically, and phytoplankton was dominated by diatoms, chrysophytes, dinoflagellates and nanoflagellates, showing high abundance ($>10^5\;cells\;l^{-1}$). In Anma-do coastal waters characterized by high dominance of dinoflagellates, high phytoplankton abundance and biomass separated from other coastal mixing area. The southeastern upwelling area was expanded from Jin-do to Heuksan-do, by a tidal mixing and coastal upwelling in the southern area of Manjae-do, and phytoplankton was dominated by benthic diatoms, nanoflagellates and Synechococcus group in this area. Phytoplankton abundance and biomass dominated by pico- and nanophytoplankton were low values in the transition waters and the central Yellow Sea. In the surface of the central Yellow Sea, high dominance of photosynthetic pigments, 19'-hexanoyloxyfucoxanthin and zeaxanthin implies that haptophytes and cyanobacteria could be the dominant group during the summer. These results indicate that the phytoplankton communities in the EYS were significantly affected by the formation of tidal front, thermal stratification, and coastal upwelling showing the differences of physical and chemical characteristics during the summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.245-252
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• 1990

The distributions of copepods and chaetognaths in waters off the southern coast of Korea were investigated to evaluate their reliability as indicator species of different water masses. The samples for this study were collected vertically from about 5m above the bottom at 28 stations along 8 transects in three different months, February, April, and August, 1988. The sampling gear used was 0.45-meter NORPAC plankton net fitted with 0.33mm mesh. Acartia clausi, Centropages abdominalis, and Sagitta crassa were found to be reliable indicator species of neritic cold waters; Pleuromamma gracilis, Undinula darwini, Calocalanus plumulosus, Calanopia elliptica, and Sagitta enflata were of oceanic warm waters; Temora discaudata and Centropages furcatus were of neritic warm waters. According to the cluster analyses of the species found, the distinctive area in February was divisible into two regions or water masses, the coastal and off-shore regions; in April, however, it was divisible into four regions. In August, it was divisible into three areas, further indicating the strength of the Kuroshio tributaries pushing toward the coast.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.356-368
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• 2011

Species composition of fishes and the recruitment properties of jack mackerel, Trachurus japonicus, in the waters around the Geumo Islands in the mid-South Sea were investigated by using both sides fyke nets every month from February to December 2010. During study period, a total of 30,503 fishes (1,380.4 kg) were collected and classified into 2 classes, 16 orders, 61 families and 121 species. The dominant species was jack mackerel occupying 80.5% of total individuals and 44.4% of total biomass. The fork length range of jack mackerel was 5.5-26.8 cm and individuals about 6 cm was appeared only in the middle and southern area of the Geumo Islands in May. The new recruitment of jack mackerel appeared from May in the waters around the Geumo Islands is probably caused by the warm water intrusion associated with the development of stratification due to the extinction of seasonal coastal cold waters by the increase of solar radiation heat. Furthermore, the jack mackerels less than 6 cm recruiting in the mid-South Sea in spring were considered as mixed ones by individuals spawned in the East China Sea and in the waters around the Jeju Island considering the collected time, migration period and spawning time of them.

• Journal of Environmental Science International
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• v.5 no.3
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• pp.347-359
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• 1996

A study was carried out on the distribution of chlorophyll a and water quality in the dry season in Yosuhae bay and adjoining sea, Southern Korea, in July of 1994. Concentration of salinity and phosphate were lower in the outer bay than in the inner bay. While nitrate and silicate were higher in the former than in the latter. We were identified with coastal waters of origin from China with the lower salinity in outer bay. The China coastal water was characteristic of high nutrients and phytoplankton biomass, such as chlorophyll a. The principal component analysis-(PCA) on the analytical data proved that high density of phytoplankton biomass , occurred under the condition of low salinity and high concentration of nissoived Inorganic nutrients. It is thought that the thermoharine structure and biological produtions of Yosuhae bay were controlled by the China coastal water in the outer bay.