• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.362-372
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• 2010

In order to understand what leads to the appearance of harmful Chattonella algae in the Yeosu coastal waters of Korea, we measured environmental parameters every week at one station from May to November, 2006, and April to October, 2007. Four species of Chattonella appeared during the monitoring period: C. antiqua, C. globosa, C. marina and C. ovata. The range of water temperature and salinity were $15.0-27.9^{\circ}C$ and 17.6~33.0 psu, respectively, when Chattonella appeared, and their maximum cell density (4,840 cells/L) was at $27.1^{\circ}C$ and 33.0 psu. During the monitoring periods, the range of dissolved inorganic nitrogen (DIN), phosphate (DIP) and chlorophyll $\alpha$ (Chl-$\alpha$) concentrations in surface waters were $1.20-52.23\;{\mu}M$ ($8.59{\pm}8.97\;{\mu}M$), $0.03-1.56\;{\mu}M$ ($0.47{\pm}0.31\;{\mu}M$) and $0.45-31.12\;{\mu}g/L$ ($3.58{\pm}4.77\;{\mu}g/L$), respectively. Chattonella occurred at low cell density when the Chl-$\alpha$ concentration increased because of supplied nutrients, whereas their cell density increased during the periods of rapid decrease in Chl-$\alpha$. The results of growth experiments based on batch culture showed that the half saturation constant ($K_s$) of C. antiqua on ammonium (${NH_4}^-$), nitrate (${NO_3}^-$) and phosphate (${PO_4}^{2-}$) were $3.89{\mu}M$, $5.01\;{\mu}M$ and $0.63\;{\mu}M$, respectively. These Ks values are higher than those reported for diatoms and other flagellates at the DIP concentration (average $0.47{\mu}M$) of Yeosu coastal waters. Although the maximum specific growth rate (${\mu}_{max}$) of C. antiqua was lower than diatoms, it was higher than those of other flagellates. Therefore, our results indicate that the DIP level in the study area was too low to support Chattonella blooms, although Chattonella species have physiological characteristics that enable them to grow more rapidly than other flagellates when nutrient levels are higher than their $K_s$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.203-213
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• 2011

The age and growth of flathead grey mullet, Mugil cephalus, were studied using samples collected from the coastal water of Yeosu from September 2009 to August 2010. Spawning season estimated from the gonadosometic index (GSI) was from November to January. A method for increasing the readability of the otolith was described and criteria for the interpretation of otolith was provided. The annual ring was formed in September once a year. Annual ring in otolith for flathead grey mullet is validated for fish aged 1-8 using the marginal increment analysis. Using the sectioned otolith, between reader precision was 84%. Also, Within-reader agreement for sectioned otolith age readings was higher (reader 1=84%, reader 2=87%). The relationship between fork length and total weight was TW=$0.022FL^{2.818}$. The estimated von Bertalanffy growth parameters for the flathead grey mullet were $L_{\infty}$=67.97cm K=0.164/year and $t_o$=-0.81year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1030-1035
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• 2021

Diving fishermen are demanding permission to use an inspirator that can efficiently catch Manila clam; however, coastal fishermenargue that the use of inspirator devastates the seabed and depletes fishery resources. Therefore, the aim of this study was to evaluate the fishing power of diving gears and its effect on coastal fishing grounds. The average time taken to fish in the seabed (4 m²) with a rake, water gun, and an inspirator was 11.17 min, 13.33 min and 7.81 min, respectivelyThe values of catch per unit time with a rake, water gun, and an inspirator were 3.35 kg/min, 2.26 kg/min, and 3.83 kg/min, respectively. Suspended sediments were observed the most in the water gun fishing area, and were observed more in April when fishing was not carried out than in February when fishing was carried out. However, the difference in the amount of sediment deposited in the fishing area using the three-fishing gears was very small. For an accurate analysis of the impact of the fishing gears on the seabed, supplementary tests such as grain size analysis and changes in benthic organisms need to be conducted.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.15-23
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• 1995

In order to investigate the relation between the phytoplankton and the catch fluctuation of set net fishing grounds located in the coastal waters of Yeosu, phytoplankton observations on the fishing ground were carried out by the training ship of Yeosu, Fisheries University from April to November in 1990, and the data obtained were compared with the catch data from the joint market of yeosu fisheries cooperative society in 1990. The results obtained are summarized as follows: 1) The phytoplanktons were more appeared in summer than in spring or autumn and their quantity was much in the shore of Dolsan-do, and little in the offshore waters distributed in the shores of Sori-do and Sejon-do, Thus, the quantity of the planktons could be used for estimating the distribution of watermass. 2) The fishes caught by the set net were arranged in the order of catch amounts as follows: Spanish mackerel > Hair tail > Common mackerel > Sardine > Anchovy > Horse mackerel > Yellow tail. The catches of anchovy and Sardine were high in April to May and Hair tail. Horse mackerel and Common mackerel were caught from June to October. But Spanish mackerel were caught during the whole period of fishing. 3) The catches by set nets showed a correlation with the quantity of phytoplanktons. The planktons appeared most in the inner waters. influenced largely by the inflow of land waters in summer. and the catches were high in summer when the offshore water was distributed least. Therefore, the most important factor influencing the catches were regarded to be the productivity of food organism in inner water into which abundant nutrients were supplied by the inflow of land waters. That is, the fluctuation of catches by set nets seemed to be influenced mainly by the productivity of food organism.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.3
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• pp.158-168
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• 2006

A study on the species composition and seasonal variations of fishery creatures caught by a funnel net was carried out in the coastal water off Dolsan Island, Yeosu from 2002 to 2003. During the study period, a total of 23 fishery creatures species were caught. Seabream(Acanthopagrus schlegeli), sea bass(Lateolabrax japonicus), mullet(Mugil cephalus), puffer(Takifugu niphobles) and rockfish(Sebastes inermis) predominated. These five species accounted for 85.1% of the total number of fishery creatures caught. Seasonal peaks of number of species occurred in summer, while those of number of individuals occurred in autumn. The lowest number of species and individuals were observed in winter. The large annual variation of diversity indices were observed from May to August. These large annual variation of diversity indices were mainly due to predominance of seabream, sea bass and mullet which accounted for most of all fishery creatures caught. The seasonal variations of fishery creatures showed that sea bass and mullet were caught mainly from spring to summer, seabream and puffer were caught mainly in autumn, and rockfish and brotula(Hoplobrotula armata) were caught mainly in winter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.448-453
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• 2015

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of Flathead grey mullet, Mugil cephalus, in the coastal waters of Yeosu. Survival rate (S) of the flathead grey mullet was 3.671. The instantaneous coefficients of natural mortality (M) and fishing mortality (F) was estimated to be 0.325/year, 0.962/year for flathead grey mullet. Also fist capure age of flathead grey mullet was 3.61year. The current biomass of the flathead grey mullet in the study area was estimated to be 19.6 M/T and $F_{0.1}$ and $F_{40%}$ were estimated 0.340/year, 0.225/year. For the stock assessment result, flathead grey mullet was not overfished but overfishing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.261-273
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• 2007

To analyze quantitative fluctuation in abundance and species composition in coastal waters of Dolsan, Yeosu, the fished were collected by gape net from March to November, 2000. The fish species caught by set net collected fishes were identified 63 species, 56 families, 42 orders, and the number of appearance and biomass was 2,230,297 individuals and 16,076.8kg. The most dominant orders were Perciformes, Clupeiformes and Tetraodontiformes which accounted for 71.4% of the total. The dominant species in number were Engraulis japonicus, Sardinops melanostictus, Trichiurus lepturus which accounted for 99.2% (2,211,642 individuals) of the total fishes collected. The dominant species in biomass were Engraulis japonicus which accounted for 79.7% (12,807g) of the total fishes collected. Temporal occurence of the dominant species such as the Engraulis japonicus, Sardinops melanostictus, Trichiurus japonicus, Ilisha elongata, Leiognathus nuchalis was closely correlated with water temperature, which is expressed as following regression equation, $y=0.0864x-0.2311(r^2＝0.3516)$. The species collected during the sampling yearly period were Engraulis japonicus, and migratory fish were Ilisha elongata, Trichiurus japonicus, Scomberomorus nipphnius, Scomber japonicus, Konosirus punctatus, Sphyraena pinguis, Pseudosciaena polyactis.

• Journal of Environmental Science International
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• v.14 no.7
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• pp.639-647
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• 2005

The aim of this study is to determine the outbreaks of nontoxic Gonyaulax polygramma Stein in Yeosu waters in place of harmful Cochlodinium polykrikoides Margalef, which has occurred annually in the same 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 membranes and prominent longitudinal ridges on the cell surface, with a cingular displacement 1.5 times their cell width. Furthermore, the location of the nucleus was posterior of large oval formation according to electron microscopy. On 6 August, 2004, the first bloom of G. polygramma occurred, the date of 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 Inorganic 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. polygramma, which is associated with a greater robustness in growth against DIN than that of C. polykrikoides in nature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.1
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• pp.39-47
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• 2008

The fluctuation in the abundance and species composition of fish was investigated using a fyke net with entrances on both sides in the coastal waters of Geumo-do, Yeosu, Chollanam-do, Korea, from May 2003 to April 2004. A total of 2,379 fishes (392.13 kg) were sampled and classified into 11 orders, 34 families, and 53 species. The dominant orders were Perciformes, Scorpaeniformes, and Pleuronectiformes, which accounted for 67.9% of the collected fishes. The dominant species was Acanthopagrus schlegelii (235 individuals, 19.00 kg), followed by Konosirus punctatus (182 individuals, 9.53 kg), and Apogon lineatus (161 individuals, 1.69 kg). The number of individuals and biomass were higher in spring and summer than in winter, and the monthly variation may be related to the water temperature. The diversity index was highest in September (H'=2.9) and lowest in December (H'=1.8). The evenness index was highest in August (J=0.9) and lowest in December (J=0.7). The dominance index was highest in December (D=0.7) and lowest in August (D=0.2). The economically important species in this area are Acanthopagrus schlegelii, Konosirus punctatus, Lateolabrax maculatus, Argyrosomus argentatus, Trichiurus lepturus, Lateolabrax japonicus, and Sebastes schlegelii.

• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.205-214
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• 2007

Marine environmental characteristics on the dinoflagellate cysts distribution in surface sediment of the southwest sea of Korea were investigated from 21 stations in September 2003, and 36 stations in June, 2004. The water mass characteristics indicated that the southwest sea of Korea is characterized by various oceanographic conditions due to coastal waters of Korea and China. The Tsushima warm currents and the cold bottom water of the Yellow Sea. Mud contents and chlorophyll a concentrations were higher in central region such as, Namhaedo, Yeosu and Goheung coast than in western region such as, Wando, Haenam and Jindo coast in the South Sea of Korea. A total of 35 taxa of dinoflagellate cysts were identified representing 21 genera, 33 species, 2 unidentified species. Cyst abundance ranged from 13 to 527 cysts $g-dry^{-1}$, showing higher abundance in the coastal areas than in western region of the South Sea of Korea. From the result of the PCA analysis, the distribution of dinoflagellate cysts was not only related to the different water masses which appeared in the southwestern sea but also to physical and biological parameters such as water temperature, light, surface sediment faces and phytoplankton biomass.