• Ocean Science Journal
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• v.40 no.2
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• pp.67-78
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• 2005

Complex physical, chemical and biological interactions off the Korean coast created several striking patterns in the phytoplankton blooms, which became conspicuous during the measurements of ocean color from space. This study concentrated on analyzing the spatial and temporal aspects of phytoplankton chlorophyll variability in these areas using an integrated dataset from a Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Advanced Very High Resolution (AVHRR) sensor, and Conductivity Temperature Depth (CTD) sensor. The results showed that chlorophyll concentrations were elevated in coastal and open ocean regions, with strong summer and fall blooms, which appeared to spread out in most of the enclosed bays and neighboring waters due to certain oceanographic processes. The chlorophyll concentration was observed to range between 3 and $54\;mg\;m^{-3}$ inside Jin-hae Bay and adjacent coastal bays and 0.5 and $8\;mg\;m^{-3}$ in the southeast sea offshore waters, this gradual decrease towards oceanic waters suggested physical transports of phytoplankton blooms from the shallow shelves to slope waters through the influence of the Tsushima Warm Current (TWC) along the Tsushima Strait. Horizontal distribution of potential temperature $(\theta)$ and salinity (S) of water off the southeastern coast exhibited cold and low saline surface water $(\theta and warm and high saline subsurface water $({\theta}>12^{\circ}C; S>34.4)$ at 75dBar, corroborating TWC intrusion along the Tsushima Strait. An eastward branch of this current was called the East Korean Warm Current (EKWC), tracked with the help of CTD data and satellite-derived sea surface temperature, which often influenced the dynamics of mesoscale anticyclonic eddy fields off the Korean east coast during the summer season. The process of such mesoscale anticyclonic eddy features might have produced interior upwelling that could have shoaled and steepened the nutricline, enhancing phytoplankton population by advection or diffusion of nutrients in the vicinity of Ulleungdo in the East Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.1037-1054
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• 2014

In this study, the status of coastal fisheries was examined based on the catch and number of fishing vessels of coastal fisheries in Korea. Comparing the status on coastal fisheries of the East Sea, Yellow Sea and South Sea in Korea, scientific evidence was made for fisheries management on coastal fisheries based on characteristics of each sea area. From 1990 to 2011, the catch of coastal fisheries in Korean waters ranged from 150,000 mt to 230,000 mt, with an average of 190,000 mt, and it accounted for 15% in average of total catch fished in adjacent waters of Korea. In order of catch by coastal fisheries, gillnet (36.7%) was the primary fishery, followed by coastal complex (24.7%), stow net (18.3%), trap (12.9%), lift net (3.9%), purse seine (3.0%) and beam trawl (0.4%) fisheries. In order of catch by species, anchovy (15.0%) had the largest proportion of total catch, followed by common squid (10.3%), akiami paste shrimp (5.2%), blue crab (3.9%) and octopus (3.7%). Of the average catch by sea area from 1990 to 2011, Yellow Sea, South Sea and East Sea were 37.4%, 34.6% and 28.0%, respectively. Since 2000s, however, the average catch of South Sea has accounted for the largest proportion. The number of permitted fishing vessels involved in 8 coastal fisheries was 55,336 vessels in average from 1997 to 2011. The number of vessels was about 47,000 vessels in 1997, and increased to 61,300 vessels until 2000, then has decreased to 44,000 vessels operating in 2011. In order of the number of permitted fishing vessels by fisheries, complex (52.4%) took the first place, followed by gillnet (31.5%), trap (13.4%), stow net (0.8%), beam trawl (0.8%), purse seine (0.6%), lift net (0.4%) and seine net (0.0%). In order of the number of permitted fishing vessels by sea area, South Sea (29,994 vessels) took the first place, followed by Yellow Sea (18,185 vessels) and East Sea (7,158 vessels). In order of the catch per unit effort (CPUE, mt/vessels) which was analyzed using catch and number of vessels in average by fishery, stow net is the highest followed by lift net, trap, purse seine, gill net, beam trawl and complex fisheries. In particular, the CPUE of complex and gill net fisheries, which accounted for the largest number of vessels were 4.0 mt/vessels and 1.6 mt/vessels, respectively. Since those are too low relative to other fisheries, it was judged to need systematical management on both fisheries.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.445-449
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• 2005

Various methods to detect the phytoplankton/red tide blooms in the oceanic waters have been developed and tested on satellite ocean color imagery since the last two and half decades, but accurate detection of blooms with these methods remains challenging in optically complex turbid waters, mainly because of the eventual interference of absorbing and scattering properties of dissolved organic and particulate inorganic matters with these methods. The present study introduces a new method called Red tide Index (Rl), providing indices which behave as a good measure of detecting red tide algal blooms in high scattering and absorbing waters of the Korean South Sea and Yellow Sea. The effectiveness of this method in identifying and locating red tides is compared with the standard Ocean Chlorophyll 4 (OC4) bio-optical algorithm applied to SeaWiFS ocean imagery, acquired during two bloom episodes on 27 March 2002 and 28 September 2003. The result revealed that OC4 bio-optical algorithm falsely identifies red tide blooms in areas abundance in colored dissolved organic and particulate inorganic matter constituents associated with coastal areas, estuaries and river mouths, whereas red tide index provides improved capability of detecting, predicting and monitoring of these blooms in both clear and turbid waters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.1
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• pp.47-55
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• 2004

A SS prediction system using GUI in coastal region has been developed to predict the dispersion of the suspended sediments occurred by dredging. The prediction system uses a finite element hydrodynamic model to calculate water level and velocities and a random-walk particle tracking model to simulate SS dispersion. The system was applied to hindcast the tidal currents and SS concentrations in the Kunsan coastal waters. The simulated tidal currents showed good agreements with the observed currents. The transport model was verified for analytic solutions and field observation showing good agreements.

• Journal of the Korean Society of Marine Environment & Safety
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• v.9 no.2
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• pp.59-64
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• 2003

The long­term trend and inter­relationship with depth of temperature and salinity in coastal waters of Korea are studied using coastal oceanographic observation and serial oceanographic data measured by National Fisheries Research and Development Institute. Temperature of coastal waters of Korea except south­western sea of Korea where cold water appears to increase in summer. In case of temperature offshore, surface temperature of East Sea increases, the reverse, for 50m and 100m decreases. Temperature in South Sea of Korea increases in whole depth and for the Yellow Sea, surface temperature increases, but for 50m decreases. In case of salinity offshore, surface salinity of East Sea decreases, but for 50m increases. Surface salinity in South Sea of Korea decreases, the reverse, form 50m and 100m increases. salinity in the Yellow Sea decrease in whole depth According to the result of inter­relationship analysis, for temperature relationship coefficients of 50m and 100m in the East Sea and South Sea of Korea is higher, however, for the Yellow sea the inter­relationship between 50m and 100m is lower. In case of salinity, the inter­relationship between surface and 50m, and for the South Sea of Korea, between 50m and 100m, and for the Yellow Sea, between surface and 50m is higher.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.57-66
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• 2020

The purpose of this study was to provide information about annual variations in catch size and changes in reproductive biology in the common octopus Octopus vulgaris, a commercially important species. Samples were collected from coastal waters off Gyeongnam, Korea, by coastal trap and coastal complex fishery from February to December 2018. Octopus vulgaris have been decreasing in this region since 2007 and catch prices have been increasing. The mantle length (ML) of O. vulgaris ranged from 1.2 to 21.2 cm and body weight ranged from 42.6 to 5,537 g. The sex ratio differed significantly from what was expected, at 0.45:0.55 (P<0.05). Mature females were found from February to December, except in October and November, and males occurred from February to December, except in October. The gonadosomatic index value was higher from May to September than in other months. The total number of eggs in fecund individuals ranged from 40,280 in 578.1 g of body weight to 138,994 in 1,666.5 g of body weight. The relationship between body weight and fecundity was F=76.486BW^1.0087 (r²=0.7897). At 50% group maturity, average weight was estimated to be 636.35 g, while it was 969.30 g at 75% maturity and 1736.55 g at 97.5% maturity. This study highlights changes in catch size and reproductive biology between 2007 and 2018. These results provide basic evidence that may be used to establish regulatory policy for O. vulgaris fisheries.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.520-524
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• 2023

Regalecus russellii, which spends most of its life in the deep sea, occasionally appears in coastal waters. However, the reasons for its appearance remain unclear. In Korea, R. russellii mainly appears along the eastern coastal waters, and most of them are caught in fishing gear, such as gill nets, or are stranded on the shore; nevertheless, the frequency of appearance is extremely low. Even if found, this species is often identified to be morphologically similar to Trachipterus ishikawae, and comprehensive analysis to identify the species through sample collection is limited. Consequently, information on the biological characteristics of R. russellii appearing in the coastal waters of Korea is scarce. Herein, the anatomical characteristics of R. russellii caught in a gill net off the Gangwon-do coast on March 14, 2023, were analyzed, and coastal water temperature was measured using an ocean buoy. Our results showed that the individual was male, its total length was 320 cm, body weight was 27.52 kg, body length was 26.62 cm, gonad weight was 619.45 g, and liver weight was 218.71 g. The stomach was full of euphausiids. The water temperature changed drastically at 15-30 m roughly a week before the R. russellii individual was caught, and the subsurface water temperature was lower than 10 ℃. Our findings provide baseline data to understand the ecological characteristics of R. russellii appearing along the eastern coast of the Korea.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.563-570
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• 2019

Red tide has caused massive fish kills in Korean coastal waters with devastating economic loss in the aquaculture industry since 1995. Remote sensing technique has shown to be effective for the detection of red tide in wide areas, where the absorption property of red tide water plays a central role in understanding the red tide reflectance. This study analyzed the optical absorption property of sea waters dominated by the dinoflagellate specie of Alexandirum affine, off the Tongyeong area in August, 2017. Water samples collected from 20 stations in the ship-based campaign were measured for absorption by pigment, suspended solid, and dissolved organic matter, with the corresponding water quality variables such as chlorophyll concentration and total suspended solid. The analysis showed that Alexandrium-dominated water exhibits strong absorption in the spectral range below 400 nm unlike that of diatom-dominated waters, and greater fluctuations in the range of 400 nm - 500 nm. The packaging effect in pigment absorption was stronger in Alexandrium-dominated waters, and the exponent in the absorption by detritus and gelbstoff is disparate for diatom and Alexandrium. In the model for the detritus and gelbstoff absorption (a_dg(λ)=a_dg(λ₀)e^-s(λ-λ₀)), the optimal exponent coefficient(s) for the Alexandrium was close to 0.01 rather than to 0.015, which was commonly use for modelling diatom waters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.75-83
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• 2020

This study investigated the effects of El Niño and La Niña on coastal upwelling in the East Sea of Korea using long-term (1967-2017) water temperature observation data and Oceanic Niño Index (ONI). As a result of time series analysis of water temperature, the occurrence frequency of summer coastal upwelling was the highest in the southeastern (Ulgi ~ Gimpo) coast. In 1987-1988 and 1997-1998, when the annual fluctuations of ONI plunged more than 2.5, the water temperature in whole coast areas of the East Sea (Busan ~ Goseung) rose by 4 ~ 7 ℃. The temperature structure of the East Sea coastal water was different when El Niño was strong with ONI above 1.5 and La Niña with strong ONI below -0.8. When El Niño is strong, the water temperature anomaly in coastal waters is negative. This is due to the strong baroclinic tilting and the formation of shallow temperature stratification in the coastal waters. The strong La Niña season is opposite to the strong El Niño season, whereas the water temperature anomaly is positive. In addition, the baroclinic tilting is weaker than the time of strong El Niño and the temperature stratification is formed deeper than the time of strong El Niño. The formation of temperature stratification at shallow depths when El Niño is strong can increase the probability of occurrence coastal upwelling caused by southerly winds in the summer season. On the contrary, when La Niña is strong, occurrence of coastal upwelling is less likely even if the southerly wind blows continuously. This is because the temperature stratification is formed at deeper than when El Niño is strong.

• Korean Journal of Environmental Biology
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• v.35 no.3
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• pp.273-288
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• 2017

An investigation focusing on the unrecorded and taxonomically undescribed indigenous has been done since 2006. Samples were collected from various sites in the coastal and offshore waters of Korea as well as around Jeju Island. Since 2008, 16 unrecorded species belonging to the family Gymnodiniaceae have been found. The species were as follows: Amphidinium thermaeum (2015), Cochlodinium convolutum (2015), C. strangulatum (2015), Gymnodinium abbreviatum (valid name: G. gracile), G. arenicola (2015), G. gracile (2015), G. dorsalisulcum (2015), G. microreticulatum (2014), G. micrum (2016) (valid name: Karlodinium micrum), G. pyrenoidosum (2016), G. simplex (2015), G. veneficum (2016) (valid name: Karlodinium veneficum), Gyrodinium aureum (2015), G. fusiforme (2015), G. dominans (2014), and Nusuttodinium latum (2016) (valid name: Amphidinium latum). (The numbers in parentheses refer to the year that the species was found). These species were newly recorded in Korean waters in this study.