• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.142-149
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• 1994

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu. The current in the vicinity of set net grounds was observed by drogue and current meter in 1990 and 1992. The results obtained are summarized as follows: The direction of tidal current at the north enterance of Yeosu bay was southerly in ebb and northwesterly in flood without the distiction of the neap tide and the spring tide. In spring tide the maximum Velocity of the tidal current was 68 cm/sec in ebb and 66 cm/sec in flood. In neap tide the maximum velocity of the tidal current was 37 cm/sec in ebb and 35 cm/sec in flood. And so the direction of residual current was the south ward mainly and 21 cm/sec. The direction of tidal current at set net fishing grounds was southwesterly in ebb and westerly or northwesterly in flood. Regardless of the distinction of neap and spring. The maximum velocity of the current in spring tide was 50 cm/sec in ebb and 40 cm/sec in flood and that in neap was 28 cm/sec in ebb and 25 cm/sec in flood. In spring tide the speed vector along the major axis of semidiurnal tide component was three times as large as diurnal tide. In neap tide, however, the speed vector was about 50% less then that in spring tide, and the semidiurnal tide and diurnal tide were equal in the size of current ellipse and the direction of major axis. The sea area had a southwesterly residual current. 11 cm/sec in spring tide and 7 cm/sec in neap tide. According to the result of drogue tracking, the vicinity of set net fishing ground had a southerly residual current which formed in Yeosu Bay and a weak westerly residual current toward Dolsando from Namhedo. Therefore, set net fishing ground in coastal water of Yeosu was distributed in boundary of inner water which formed from Seamjin river and offshore water supplied from the vicinity of Sorido and Yochido.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.1
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• pp.1-10
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• 1993

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu, oceanographic observations on the fishing grounds were carried out by the training ship of Yeosu Fisheries University from Jun. 1988 to Dec. 1990. The resultes obtained are summarized as follows; 1) The water mass in the fishing grounds were divided into the inner water (29.50-31.00$\textperthousand$), the mixed water (31.10-32.70$\textperthousand$) and the offshore water (32.70-34.30$\textperthousand$) according to the distribution of salinity from T-S diagram plotted all salinity data observed from Jun. 1988 to Dec. 1990. In spring the mixing water prevailed and in summer the inner and mixing water. But in autumn and winter the mixing and offshore waters prevailed. 2) The inner water which was formed by land water from the river of Somjin and the precipitation in the Yeosu district flowed southerly along the coast of Dolsando and spread south-easterly in the vicinity of Kumodo. The inner water and offshore water which supplied from the vicinity of Sorido and Yokchido formed the thermal front and halofront. 3) As the mixing water flowing from the western sea of Cheju to the southern coast of korea was low in temperature, the water mass of low temperature which appeared at the offshore bottom of Sorido in summer was considered not to be the Tsushima warm current. 4) As vertical mixing was made frequently in spring, autumn and winter, the differences in temperature and salinity between surface and bottom was respectively small. In summer, however, the mixing was not made because of the inner water expanded offshore through the space between surface and 10m layer and so a thermocline of $2.0^{\circ}C$/10m and halocline of 4.0$\textperthousand$/10m respectively in vertical gradient was formed. 5) In the vicinity of Dolsando and Kum a water low in salinity prevailed, but in the vicinity of Namhaedo and YoKchido the reverse took place. The inner and mixing waters formed at these arease was limited to the observation area not to spread widely.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.2
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• pp.94-108
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• 1993

In order to investigate the relation between the environmental properties and catch fluctuation of set net fishing ground located in the coastal waters of Yeosu, oceanographic observation and catches on the grounds were carried out from Jan. to Dec. in 1990 and 1992. The results obtained are summarized as follows; 1) Because of the surveyed area is a costal shallow water, the fishing ground was influenced largely by atmospheric phenomena such as air temperature. precipitation. etc. and so showed large variations in temperature and salinity yearly. The inner water flowed out mainly between Yeosu ad Namhe-do, and then through Kumo-do between Dolsan-do and Kumo-do. On the other hand, off shore water was supplied into the fishing ground from the vicinity of Sori-do and Yokchi-do. thus the fishing ground was occupied usually by various sources of water. 2) The water mass in the fishing ground were divided into the inner water(29.0～30.6$\textperthousand$) and the mixed water(31,7～32.2$\textperthousand$) and off shore water(32.3～32.8$\textperthousand$) accourding to the distribution of salinity from T-S diagram plotted all salinity data observed in 1990 and 1992. In summer the inner and mixing water which was formed by river flowed southerly and spread south-easterly in the vicinity of Kumo-do. The off shore water which supplied from the vicinity of Sori-do and Yokchi-do and inner water formed the thermal front and halo front in summer. 3) The fishes caught by the set net were arranged in the order of catch amounts as follows: Spanish mackerel>Horse mackerel >Hair tail>Common mackerel> Sardine> Anchovy. The Catches of anchovy and sardine were high in April to May and those of hair tail and horse mackerel in July to September, but spanish mackerel were caught during the whole period of fishing. When inner water and mixing water appeared respectively and inner water and mixing water speared together in the set net fishing ground, the set net showed a high catch.

• Journal of Environmental Science International
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• v.16 no.10
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• pp.1119-1125
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• 2007

We examined the horizontal distribution of salinity and the concentrations of DIN and DIP after heavy rain-fall events in coastal areas of South Korea from Yeoja Bay to Narodo and from Gwangyang Bay to Geomodo to determine whether fresh water actually flows into areas of Cochlodinium polykrikoides red tides and to observe its effect on the growth of this organism after heavy rainfall. Following heavy rainfall (155 mm) in the Yeosu and Suncheon regions, the average salinity was 21 and 29 psu at Yeoja Bay and in the coastal waters of Narodo, respectively. After 126 mm of rainfall, the values were 19 and 25 psu in the coastal waters of Yeosu and Geomodo, respectively. This may have been caused by an influx of fresh water, after the rainfall event, into the open sea coastal areas around Narodo and Geomodo from the Dong and Seomjin Rivers, which are about 3540 km away. After the rainfall, the concentrations of $NH_4-N,\;NO_2-N$, and $PO_4-P$ were slightly increased; however, the concentration of $NO_3-N$ was greatly increased and diffused throughout the coastal areas of Narodo and Geomodo, which frequently experience C. polykrikoides blooms. The influence of $NH_4-N,\;NO_2-N$, and $PO_4-P$ on the occurrence of C. polykrikoidesred tides in coastal areas around Narodo and Geomodo after heavy rainfall does not appear to be great. Instead, the occurrence C. polykrikoides red tides in the coastal areas of Narodo and Geomodo seems to be facilitated by $NO_3-N$.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.505-521
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• 2007

This study estimated response of water duality and pollutant behavior according to the discharge and reuse of treated wastewater by three-dimensional eco-hydrodynamic model, and suggest plan that water quality management and environmental restoration in the coastal area including urban stream of Yeosu, Korea. Dispersions of low-saline water and COD by treated wastewater loads (design facility capacity, about $110,000m^3/d$) were very limited in near of effluent site. Nutrients, however, increase compared to the other water quality factors, especially total nitrogen was very sensitive to input loads. When reuse some of treated wastewater to Yeondeung stream, nitrogen was big influence on estuarine water quality. Although current characteristics of treated wastewater such as discharge and water quality were negligible to the change of marine environment, effluent concentration of COD, TN and TP, especially 40% of TN, are reduced within the allowable pollutant loads for satisfy environmental capacity and recommended water duality criteria. Also, controls of input point/non-point sources to Yeondeung stream and base concentration of pollutants in coastal sea itself are very necessary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.642-647
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• 2016

Postlarval and juvenile anchovies Engraulis japonicus were collected using a gape net with wings in the coastal waters of Yeosu in July and August 2015, and their gut contents were analyzed. The size range of the postlarvae was 11.0-24.2 mm (notochord length) and that of the juveniles was 25.1-37.4 mm (standard length). Guts were empty in 64.5% of postlarvae and in 51.7% of juveniles. The dominant prey organisms in the guts of both postlarvae and juveniles were copepoda. Calanoida were important prey organisms for postlarvae and were dominated by nauplii of Paracalanus sp. and Calanus sp. as well as unidentified copepod naupill. Calanoida were also important in the diets of juveniles, whose gut contents were dominated by Paracalanus sp. and Cirripedia. Gut compositions were significantly different (P<0.05) among three body size levels in postlarvae and juveniles. As the body size of the postlarvae and juveniles increased, Calanoida constituted a larger proportion of the gut contents, while the proportion of copepod nauplii decreased.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.633-642
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• 2014

Monthly variation in abundance and species composition of the fishes were investigated based on specimens collected by gill net in coastal water of Yeosu from October, 2009 and February, May, August, 2010. The collected fishes were 1,529 individuals (183,840g) of the total, identified into 6 orders, 16 families and 24 species. The most dominant order fish was Perciformes comprised 9 species, 7 families, and followed Pleuronectiformes comprised 5 species, 3 families, Scorpaeniformes comprised 5 species, 2 families. These 3 orders constituted 81.1% of the total collected fish. During the study, most dominant species was Hexagrammos otakii accounted for 189 individuals (12.4%) of the total, followed by Lateolabrax japonicus 165 individuals (10.8%), Hexagrammos agrammus 154 individuals (10.0%). The fish was collected by a gill net in coastal water of Yeosu from October, 2009 and February, May, August, 2010, the diversity index of the fishes was 2.09~2.66, which was the highest in August, 2010 and the lowest in February, 2010. The evenness index of them was 0.84~0.89, which was the highest in August, 2010 and the lowest in February, 2010 and the richness index of them was 2.02~3.14, which was the highest in October, 2009 and the lowest in February, 2010. The analyzed species diversity index by the each stations was 2.47~2.66 and the evenness index was 0.84~0.90 and the richness index 2.99~3.37. The similarity of community structure per season was very high which was the least in spring and fall. In addition, the community structure was very similar in state 3 and 2 out of each stations.

• Journal of Environmental Science International
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• v.31 no.12
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• pp.1027-1038
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• 2022

The intertidal zone has both land and marine characteristics and shows complex weather environments. These characteristics are suited for studying climate change, energy balance and ecosystems, and may play an important role in coastal and marine weather prediction and analysis. This study was conducted at Odo Island, approximately 300m from the mainland in Yeosu. We built a weather observation system capable of real-time monitoring on the mud flat in the intertidal zone and measured actual weather and marine data. Weather observation was conducted from April to June 2022. The results showed changes in air temperature and water temperature with changes in the tide level during spring. Correlation analysis revealed characteristic changes in air temperature and water temperature during the day and night, and with inundation and exposure.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.241-244
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• 2005

The aim of this study was to determine the first outbreaks of nontoxic Gonyaulax polygramma Stein in Yeosu waters in place of harmful Cochlodinium polykrikoides Margalef, which has occurred annually in the same coastal region since 1995. The observation of cellular arrangement and structure by electron microscopy showed that G. polygramma isolated from Yeosu waters had a few spines connecting with mem-branes and prominent longitudinal ridges on the cell surface, with a cingular dis-placement 1.5 times their cell width. Furthermore, the location of the nucleus wasposterior of large oval formation according to electron microscopy. On 6 August, 2004,the first bloom of G. pozygramma occurred, the date of own its disappearance was with a maximum cell density of 8,000 cells ml$^{-1}$ on 21 August, 2004. During the period of this study, the horizontal distribution of sea water temperature and salinity showed a strong coastal front, whereas the front of DIN (Dissolved Inoganic Nitrogen) was significantly different between the occurrence and disappearance of G. polygramma blooms. These results suggested that the process of the breakdown of stratification by wind and a low level of inorganic nitrogen play important roles in the rapid growth of G. polygrmma, which is associated with a greater robustness in growth against DIN than that of C.polykrikoides in nature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.4
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• pp.150-157
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• 1988

The oceanographic condition around the set net fishing ground in Yeosu Bay was investigated by the oceanographic observation in June, July and August, 1988. Also the catch of the set net was analized by daly catch data of the three set net fishing ground from April to September, 1988. The results obtained are as follows: 1) The coastal surface water is high temperature and low salinity through the influence of land, and the off shore water and bottom water are low temperature and high salinity. 2) The eddy current and the sharp thermocline in June appeared in August at the set net fishing ground, and a good catch appeared in June and August. 3) The surface temperature and salinity at the set net fishing ground are 11$^{\circ}C$ to 27$^{\circ}C$ and 31.60$\textperthousand$ to 34.80$\textperthousand$. The surface temperature and salinity of a maximum good catch are 21$^{\circ}C$ and 33.80$\textperthousand$ to 33.99$\textperthousand$ respectively. 4) The dominant species of fish were spanish mackerel, scad, anchovy, sardine, common mackerel, hairtail, crab, yellow tail, in order of catch.