• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.538-548
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• 1993

In order to estimate the influence of wind stress in the southwestern coastal waters of the Japan Sea, the wind stress was estimated from the shipboard wind data of the Fisheries Research and Development Agency along the serial observation lines and Buoy No. 6 of the Japan Meteorological Agency. 5,100 wind data are used to construct a data set of monthly mean wind stress during 10 years from 1978 to 1987. The negative values of the mean zonal wind stress curl at Ulleung Basin in the study area seem to be responsible for the formation of the warm core. The volume transport of the East Korea Warm Current are estimated quantitatively by the variations of the Ekman transport associated with the reversing direction of the monsoon. And the distribution of the warm core is explained by the simple three layer model.

• Journal of Aquaculture
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• v.11 no.1
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• pp.67-75
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• 1998

Experiments were performed to obtain cryopreservation techniques of black seabream (Acanthopagrus schlegeli) sperm. For sperm collection, brood stock reared in recirculating seawater system and fed with the commercial feed during experimental period. The results indicated that following cryopreservation method in block seabream sperm could be employed. Post-thaw survival rate of sperm revealed the highest value ($80{\pm}1.4$%) in 3% sodium citrate as a diluent for the cryopreservation. Cryopreserved sperm diluted with 5.4% glucose showed the highest fertilization rate to the ovulated eggs. Glycerol was a better cryoprotectant than dimethyl sulfoxide in sperm cryopreservation : survival rate and fertilizing capacity of cryopreserved sperm were decreased according to increase of glycerol concentration and varied in renges of 0.8~59.3% and 32.5~69.4% with 5~30% glycerol, respectively. A few of cryopreserved spermatozoa showed the enlarged head with granulated chromatin and ruptured plasma membrane by freezing and thawing injuries compared with unfrozen normal spermatozoa.

• Journal of Aquaculture
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• v.20 no.3
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• pp.173-177
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• 2007

An experiment was performed to obtain cryopreservation techniques of starry flounder (Platichthys stellatus) sperm. Milt obtained from 24 males were cryopreserved using two diluents, artificial seminal plasma (ASP) and Stein's solution (SS) with three cryoprotectants, dimethyl sulfoxide (DMSO), methanol, and glycerol concentrated from 5% to 20%. Post-thaw sperm activity (motility and/or speed) revealed the highest in 10% DMSO and 15% methanol in ASP and SS as diluent. Motility and speed of cryopreserved sperm were decreased according to increase of glycerol concentration. To conclude, DMSO was a better cryoprotectant than methanol or glycerol for cryopreservation of starry flounder sperm. Glycerol was incongruent cryoprotectant because of toxic to starry flounder sperm. Most cryopreserved spermatozoa without cryoprotectant showed the enlarged head with granulated chromatin and ruptured plasma membrane by freezing and thawing injuries compared with unfrozen normal spermatozoa.

• 한국해양학회지
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• v.18 no.1
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• pp.1-9
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• 1983

The northern boundary of the Tsusgima Current and its fluctuations are divcussed in the Japan Sea in summer. This current was characterized with high slinity, and its path was traced by following the salinity maximum on the basis of oceanographical data collected during the period from 1963 to 1979. The salinity maxima (34.45-34.85 ) of the Tsushima Current in the areas between 29 N in the East China Sea and northern part of the Japan Sea were found at depths between 46m and 135m. The representative thermosteric anomaly corresponding to the salinity maximum eas examined in order to analyze the advection of this currint. In the Tsushima Current region in the Japan Sen, the thermosteric anomaly values in the layer of salinity maximum during the period of 1970 to 1979 was beween 220 cl/t and 260 cl/t. In general, as the current moves northward its salinity decreascs, its thermosteric anomaly decreases and the depth of salinity maximum becomes shallower. The northern boundary of this current, which is indicated by 34.4 isohaline on 240 cl/t isanosteric surface during the study period of ten years, was confined to south of 40 N of the Japan Sea. The 34.4 isohaline edvealed two types of flow; one of them flows northward along the eastern coast of South Korea and then meanders eastward, while the oter flows basically northeastward along the coast of Japan. The meanders of northern boundary of this currint idrntified th isohaline in this word were nearly similar to those studied by others on the bases of isotherm analysis.

• Journal of Aquaculture
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• v.16 no.4
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• pp.262-266
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• 2003

In order to develop a method for the cryopreservation of fish embryos, the determination of optimal concentrations of dimethyl sulfoxide (DMSO), ethylene glycol and glycerol as individual cryoprotectants was performed by using the early embryos of black seabream, Acanthopagrus schlegeli. Optimal concentrations of cryoprotectants were assessed in terms of effects on mortality, median lethal concentration and hatching rate of embryos. The mortality of black seabream embryos immersed in cryoprotectants was related to the concentrations of cryoprotectants and immersion times. The toxicity to embryos was lower in order of DMSO, < ethylene glycol, < glycerol. The results from the mortality, median lethal concentration and hatching rate evaluations suggest that DMSO was the most effective cryoprotectant for black seabream embryos followed by ethylene glycol, and suitable concentrations of DMSO and ethylene glycol were 2.0∼2.25M and 1.0∼1.78M, respectively, with 20 minutes of immersion time.

• Animal Systematics, Evolution and Diversity
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• v.8 no.1
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• pp.107-132
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• 1992

To perform the systematic study on Korean Ophiuroidea the specimens collected from total 92 localities in the Sea of Japan and the Korea Strait during the period from April, 1969 to October, 1991 were classified, As a result, 41 phiuroid species belonging to 18 genera, 8 families, 4 suborders and 2 orders were identified , of which 6 species, namely, Ophiactis brachygenys, Ophiactis modesta, Ophiopholis brachyactis, Amphioda cyclaspis, Amphipholis kichii, Ophionereis eurybrachyiplax have not been reported in Kiorea before. With regard to the distribution of species , 24 species (58.5%) were found only in the Korea Strait, 9 species (22.0%) occurred either in the Sea of Japan and the Korean Strait and 8 species (19.5%) only in the Sea of Japan. Ophiothrix exigua was predominantly collected from 44 localities of total 92 localities examined and also from the Korea Strait, but Ophiura sarsii was the commonest speices in the SEa of Kapn . Eighteen temperature species(43.9%) were found in the greatest number, and then 15 tropical species (36.6%) , 7 boreal species (17.1%) and 1 cosmopolitan species(2.4%) were found.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.1
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• pp.13-26
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• 2016

Sea water level variations are generally influenced by a variety of factors such as tides, meteorological forces, water temperature, salinity, wave, and topography, etc. Among non-tidal conditions, atmospheric pressure is one of the major factors causing water level changes. In the East Sea, due to small tidal range which is opposite to large tidal range of the Yellow Sea, it is difficult to predict water level changes using a numerical model, which consider tidal forcing only. This study focuses on the effects of atmospheric pressure variations on sea level predictions along the eastern coast of Korea. Telemac-2D model is simulated with the Inverted Barometer Effect(IBE), and then its results are analyzed. In comparison between observed data and predictions, the correlation of prediction with IBE and tide is better than that of tide-only case. Therefore, IBE is strongly suggested to be considered for the numerical simulations of sea level changes in the East Sea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.296-305
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• 2018

Maturity and spawning of the pointhead flounder, Hippoglossoides pinetorum were investigated on the basis of samples collected in the coastal waters off Gangwon-do, East Sea from January 2012 to December 2013. The average total length of H. pinetorum was 25.0 cm and 21.9 cm for females and males, respectively. The spawning period was from May to July according to monthly changes gonadosomatic index (GSI) and maturity stages. The spawning period in Gangwon-do was delayed relatively to that in Gyeongbuk-do. The mature egg diameter ranged between $300-700{\mu}m$. The relationship between TL and fecundity (F) was F = 63.574 TL - 1471.3 ($R^2=0.7603$), that is, the larger total length, the more fecundity H. pinetorum had. We estimated that the TLs at 50% group maturity were 25.6 cm for females and 19.9 cm for males. The spawning ecology by sea area should be considered efficient resource management for H. pinetorum. Furthermore, it is necessary to study more on the relationships among growth, maturity and water temperature variations in the East Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.87-91
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• 2019

Effects of feeding frequency on the growth performance of juvenile starry flounder Platichthys stellatus were investigated. One thousand fifty fishes were distributed into 15 of 500-L flow-through tanks. Triplicate groups of were fed experimental diet with five feeding frequency (one meal every two days, one meal a day, two meals a day, three meals a day and four meals a day) for 9 weeks. Weight gain and specific growth rate (SGR) of fish fed two meals a day were higher than those of fish fed one meal 2 days and one meal a day, but not different from those of fish fed three meals a day and four meals a day. Feed consumption of fish fed two meals a day was not different from that of fish fed three meals a day and four meals a day. Feed efficiency (FE) and protein efficiency ratio (PER) of fish fed two meals a day were higher than those of fish fed all other diets, except for three meals a day. These results suggest that the optimal feeding frequency is two meals a day for the optimum growth performance of juvenile starry flounder under the experimental conditions.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.729-742
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• 2020

In this study, we analyze seabottom conditions and characteristics integrated with topographic data, seafloor mosaic, underwater images and orthophoto(drone) of soft-hard bottom area around the Sib-Ri rock in the northern shore of the East Sea(Gyeongpo Beach, Gangneung). We obtained field survey data around the Sib-Ri rock(about 600 m × 600 m). The Sib-Ri rock is formed by two exposed rocks and surrounding reef. The artificial reef zone made by about 200 ~ 300 structures is shown the western area of the Sib-Ri rock. The underwater rock region is extended from the southwestern area of the exposed the Sib-Ri rock with 9 ~ 11 m depth range. The most broad rocky seabottom area is located in the southwestren area of the Sib-Ri rock with 10 ~ 13 m depth range. The study area were classified into 4 types of seabottom environment based on the analysis of bathymetric data, seafloor mosaics, composition of sediments and images(underwater and drone). The underwater rock zones(Type I) are the most distributed area around the Sib-Ri Rock(about 600 m × 600 m). The soft seabottom area made by sediments layer showed 2 types(Type II: gS(gravelly Sand), Type III: S(Sand)) in the areas between underwater rock zones and western part of the Sib-Ri rock(toward Gyeongpo Beach). The artificial reef zone with a lot of structures is located in the western part of the Sib-Ri rock. Marine algae(about 6 species), Phylum porifera(about 2 species), Phylum echinodermata(about 3 species), Phylum mollusca(about 3 species) and Phylum chordata(about 2 species) are dominant faunal group of underwater image analysis area(about 10 m × 10 m) in the northwestern part of the Sib-Ri rock. The habitat of Phylym mollusca(Lottia dorsuosa, Septifer virgatus) and Phylum arthropoda(Pollicipes mitella, Chthamalus challengeri hoek) appears in the intertidal zone of the Sib-Ri rock. And it is possible to estimate the range and distribution of the habitat based on the integrated study of orthphoto(drone) and bathymetry data. The integrated visualization and mapping techniques using seafloor mosaic images, sediments analysis, underwater images, orthophoto(drone) and topographic data can provide and contribute to figure out the seabottom conditions and characteristics in the shore of the East Sea.