• Journal of Environmental Science International
• /
• v.30 no.10
• /
• pp.811-820
• /
• 2021

The population variation of Spanish mackerel (Scomberomorus niphonius) according to its major prey abundance was analyzed using monthly catches of coastal set net fisheries in the southern waters off Gyeongsangnam-do and eastern waters off Gyeongsangbuk-do of Korea from 2006 to 2019. The abundance of Spanish mackerel and its prey species fluctuated almost simultaneously with time lags of +2 to -2 months between the set net fisheries in the southern and eastern waters. The generalized additive model revealed that the abundance of Spanish mackerel was influenced by its prey species such as hairtail and anchovy in southern waters, and common mackerel and horse mackerel in eastern waters. The model deviance explained 49% and 42% of Spanish mackerel abundance in southern and eastern waters respectively. These results suggest that the abundance of Spanish mackerel is affected by seasonal migratory prey fish species in the coastal areas and can be linked to their northerly migration.

• Journal of Environmental Science International
• /
• v.15 no.6
• /
• pp.539-562
• /
• 2006

The clarification of spatial-temporal patterns of phytoplankton from southern coastal waters during the period of March to November in 2004 was carried out. Total cell numbers were shown in 5,286 cells $ml^{-1}$ on March and reached to encounter a peak of 27,775 cells $ml^{-1}$ on July. Mean cell number was also shown in maximum of 1,587 cells $ml^{-1}$ on July, which recorded approximately two times higher than on June. The cell number of phytoplankton from southmiddle waters attained an abundance of ${\geq}35%$ regardless of months, which was the highest the abundance of phytoplankton in 2004 than any other waters in this study. Southwestern waters were lower the cell number of 2-5 times than those of southmiddle and southeastern waters. In particular, Prorocentrum occurred in southeastern waters on June and the highest cell number of 8,200 cells $ml^{-1}$ around Tongyeong region on July, which was recorded to occupy the value of 60.9% in southeast waters. The abundance of Skeletonema costatum as a dominant taxa in southwest was shown in ${\geq}60%$ on March, July, September, and October, whereas was also recorded to achieve the abundance of above 80% in southmiddle waters on March, July, and September. The majority of the taxa in southeastern waters was diatom: Eucampia zoodiacus, and Chaetoceros spp.. They occupied above 45%. On November, most of southern waters were abundant to Chaetoceros spp. On the basis of cluster analysis using SPSS ver 10.0, phytoplankton occurring on March showed somewhat no correlation with all of southern waters. In contrast to on March, the relationship between southwestern and southmiddle waters was shown on August and November, indicating a distinction from southeastern waters. However, the distance between southwestern/middle and southeastern waters appeared to be less than 5. Consequently, the abundance of phytoplankton in southern waters showed much fluctuations in temporal and spatial assays. In particular, southwestern and southmiddle waters during the periods of summer and winter appeared to be a similar to environmental characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.34 no.1
• /
• pp.52-61
• /
• 1998

We studied behaviour pattern of anchovy (Engraulis japonicus) shoal by a method of shoal echo integration and tested species identification by a method of artificial neural network using the acoustic data collected in the East China Sea in March 1994 and in the southern coastal waters of the East Sea of Korea in March 1995. Between areas, frequency distribution of 10 shoal descriptors was different, which showed characteristics of shoal behaviour in size, bathymetric position and acoustic strength. The range and mean of shoal size distribution in length and height was wider and bigger in the southern coastal waters of the East Sea than in the East China Sea. Relative shoal size of China Sea. Fractal dimension of shoal was almost same in both areas. Mean volume reverbration index of shoal was 3 dB higher in the southern coastal waters of the East Sea than in the East China Sea. The depth layer of shoal distribution was related to bottom depth in the southern coastal waters of the East Sea, while it was between near surface and central layer in the East China Sea. Principal component analysis of shoal descriptors showed the correlation between shoal size and acoustic strength which was higher in the southern coastal waters of the East Sea, than in the East China Sea. Correlation was also found among the bathymetric positions of shoal to some degree higher in the southern coastal waters of the East Sea than in the East China Sea. The anchovy shoal of two areas was identified by artificial neural network. The contribution factor index (Cio) of the shoal descriptors between two areas were almost identical feature. The shoal volume reverberation index (Rv) was showed the highest contribution to the species identification, while shoal length and shoal height showed relatively high negative contribution to the species identification.

• 한국해양학회지
• /
• v.2 no.1_2
• /
• pp.1-12
• /
• 1967

As a part of the primary production in the coastal water of Korea Seas on October-November 1964 and June-July 1965, quantitative phytoplankton materials by the net haul were obtained. This paper deals with a study on the distribution quantity and specific composition of the phytoplankton in the same waters. 76 species of diatoms and 8 species of dinoflagellates in October-November 1964, and 74 species of diatoms and 7 species of dinoflagellates in June-July 1965 were found. In autumn of 1964 and spring of 1965, there occured 90 species of diatoms and 10 species of dinoflagellates, and 60 species of diatoms and 5 species of dinoflagellates were encountered in both seasons. The maximal total quantity of phytoplankton were observed at Pohang (27,844,000 cell/㎥), Ulsan (25,186,000 cells/㎥) and Yosu (12,829,000 cells/㎥) in June-July 1965 and the smallest (16,000 cells/㎥) at Jukbyon in the coast of the Sea of Japan in October-November 1964. The coastal water of Korean Seas, as well as in the primary production study, is divided into four regions by the phytoplankton characters; coastal waters of the Sea of Japan, the east part of the Southern Sea, the west part of the Southern Sea and the Yellow Sea. The coastal waters of the Sea of Japan and the east part of the Southern Sea, in generally, are rich in the phytoplankton. In the coast of the Sea of Japan, species of Chaetoceros and Bacteriastrum prevail and uncommon in species of Coscinodiscus and Rhizosolenia. In the east part of the Southern Sea, on the other hand, uncommon in species of Chaetoceros and Bacteriastrum, and species of Coscinodiscus Rhizosolenia and hemiaulus indicus prevail. The coastal waters of the west part of the Southern Sea and the Yellow sea are both poor in the phytoplankton but Coscinodiscus species prevailed comparatively.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.4
• /
• pp.529-541
• /
• 2015

We examined the species composition and community structure of demersal fish in the middle and southern coastal waters of the East Sea of Korea by surveying a commercial Danish seine fishery from 2010 to 2013. We considered the waters north of $37^{\circ}N$ as middle and those south of $37^{\circ}N$ as southern waters. A total of 79 demersal fish species belonging to 18 families were collected. Of these, 59 species (77.6%) inhabited only the East Sea as opposed to the West and South Seas of Korea, and most were resident species. The species and biomass were similar between the two portions of the study area. The sandfish Arctoscopus japonicus (78.0%) and the blackfin flounder Glyptocephalus stelleri (65.1%) were the most common species and accounted for the most biomass in the middle and southern waters, respectively. Fish were most abundant at shallow depths (50-100 m) in the middle portion of the East Sea. Using a cluster analysis, we divided the species composition and community structure at the sampling stations into three groups: middle portion (group A), deep area of the southern portion (group B), and shallow areas of the southern portion (group C). A. japonicas and G. stelleri were dominant in groups A and B, while G. stelleri and Clupea pallasii were dominant in group C.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.4
• /
• pp.401-409
• /
• 1983

The distribution of anchovy eggs and larvae was studied using the ichthyoplankton samples and oceanographic data collected in the western and southern waters of Korea over the period of April through June in 1981 and 1982. Three water masses, the Tsushima Warm Current, the South Korean Coatal Water and the Yellow Sea Bottom Cold Water, are found to exert extensive influences of the distribution of anchovy eggs and larvae. The Tsushima Warm Current contacts with the South Korean Coastal Water to produce a coastal front between Cheju Island and Tsushima Island in the southern waters of Korea. Off the west coast of Korea, a coastal front is also formed running parallel with the western coast-line of Korea in the area between the Yellow Sea Bottom Cold Water and the extended part of the South Korean Coastal Water. In the southern waters of Korea anchovy eggs were found chiefly in the coastal waters inside the front, and larvae appeared to both sides on the front. The distribution of anchovy eggs and larvae off the west coast of Korea, however, was limited largely to the coastal waters of more than $12^{\circ}C$ in temperature. In the southern waters of Korea prelarvae appeared in the coastal area, and postlarvae in the offshore area. While in the western waters of Korea prelarvae were found in the southern part of the waters, and postlarvae in the northern part. Anchovy eggs and larvae were distributed in the considerably limited area of the coastal waters off the south coast of Korea in 1981 when the temperature gradient of the coastal front was sharper than in 1982.

• Fisheries and Aquatic Sciences
• /
• v.12 no.3
• /
• pp.240-248
• /
• 2009

Distribution and abundance of planktonic shrimps were studied in the southern sea of Korea from 1987 to 1991. Nine species of five genera belonging to three families were identified. Of these, Leptochela sydniensis and Lucifer intermedius were predominant species and Lucifer penicilifer and Lucifer typus were common species. Remaining five species, Acetes chinensis, Leptochela gracilis, Lucifer chacei, Process wheeleri and Sergestes similis occurred sporadically and rarely. The distribution pattern of planktonic shrimps varied with species and sampling periods. L. intermedius occurred abundantly along inshore waters. L. penicilifer and L. typus appeared in both inshore and offshore waters, but more abundantly in offshore waters under influence of the Tsushima Current. In conclusion, the distribution patterns of planktonic shrimps may be related with hydrographic characteristics and seasonality in the southern sea of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.3
• /
• pp.208-214
• /
• 1990

Phytoplankton samples for this study were collected by Van Dorn Sampler at 28 oceanographic stations in the southern waters of Korea in February, April and August, 1988 to characterize the distribution and species composition of phytoplankton and their relation to the movement of water masses. During the study periods, phytoplankton standing crops in the southern waters were maximum in April and minimum in February. When the geographical distribution and abundance of the phytoplankton were considered, the highest standing crops were found near the front zone formed between Cheju Island and Tsushima Island. Therefore, their abundance depends ell the location of the front zone. On the other hand, there were relatively low standing crops in the open sea off the coastal area from the front zone in February and August. The cause of the unusal low standing crops found in August at the station 205/01, the central part of the coastal area of the southern waters where the largest standing crops occurred in February and April, seems to be due to the intrusion of Tsushima warm waters. This is because the waters at the station have high temperature and salinity, poor dissolved oxygen and nutrient salts, which are identical to the characteristics of proper Tsushima warm waters. It seems that these warm waters may affect the poor productivity in this area. Seventy-two species in thirty-three genera of the phytoplankton were indentified from the samples. Among them, 61 species in 27 genera belong to diatoms and 12 species in 7 genera to dinoflagellates. The largest number of phytoplankton species occurred in August while the largest number of the tells in April. Predominant species were Eucampia zodiacus in February, Skeletonema costatum and Chaetoceros curvisetus in April and Chaetoceros affinis in August. Eucampia zodiacus which was dominant in February and April seems to be a indicator of the southern coastal waters of Korea and mixed waters west of Cheju Island.

• Journal of the korean society of oceanography
• /
• v.38 no.3
• /
• pp.101-110
• /
• 2003

We made intensive observations on the coastal upwelling off the coast of the southern East Sea from June to August in 2001. The upwelling exhibited a weekly waxing and waning. The coastal upwelling of the year 2001 was characterized by abrupt outbreaks and the small local scale. Upwelling occurred more frequently off the coast of Ulsan and Gampo as reported by the earlier observers. The spread of freshly upwelled colder water was varied by each upwelling event. Generally cold waters were carried away northeastward off Pohang province. The upwelled cold waters were saltier than the resident surface waters. The pH and salinity-normalized alkalinity support the idea that the upwelled waters originate from the interior of the East Sea. The extraordinarily high concentration of dissolved oxygen suggests that the upwelled waters are closely connected to the southward flowing North Korea Cold Current. Although a lower primary productivity was reported for the upwelling region, underway surface fluorescence measurement revealed that the recently upwelled waters supported up to an order of magnitude higher algal biomass than the ambient waters. Because thermohaline circulation of the East Sea is so vigorous, with an estimated time scale of less than one hundred years, that the coastal upwelling should be considered not as an anomaly but as a regular component of a circulatory system. A quantitative understanding of upwelling seems to be a key to elucidate material cycling and the associated biological production in the East Sea.

• Journal of Environmental Science International
• /
• v.18 no.2
• /
• pp.141-151
• /
• 2009

Temperature, salinity, COD, DIN (Dissolved Inorganic Nitrogen), DIP (Dissolved Inorganic Phosphorus), and Chlorophyll ${\alpha}$ obtained from the southern coastal waters during the period of 2003 to 2005 were analyzed. Variability in temperature was not found between groups in southern coastal waters, but significantly different depending on sampling sites (p<0.05). The average temperature in 2003 estimated at $18.33^{\circ}C$ that was annually increased by 2005 and significantly different based on statistics (p<0.05). Unlikely to temperature, salinity was significantly different depending on sampling sites, as well as monthly variations (p<0.05). Likewise to temperature, the value of salinity was annually increased. COD estimated at the average of $>1.7\;mg\;l^{-1}$ for three years, indicating optimal water quality. The fluctuations of nutrients were extremely shown in different sampling sites and monthly variations. Chlorophyll a recorded above $2.0{\mu}g\;l^{-1}$ which was associated with high primary phytoplankton, whereas it showed much fluctuations in temporal and spatial, In particular, Tongyong, Jaranman, Jinjuman, and Samcheonpo located in the southeast were the highest fluctuations in water quality than any other regions. The correlation between salinity/COD and nutrients/chlorophyll a was strongly negative or positive, which was possibly associated with much the introduction of run-off water as well as rainfall in summer.