• Korean Journal of Environmental Biology
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• v.17 no.3
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• pp.293-303
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• 1999

Fish fauna of fishes collected from the Saemankum area in the west coast of Chollabuk-do was studied from October 1996 to April 1999. The specimens collected from the five sites in this area were identified into 107 species belonging to 83 genera and 52 families. Of them the largest group of fishes was order Perciformes, comprising 50 species and 21 families, and showed 46.7% in total numbers of species. Next larger groups were orders Scorpaeniformes and Pleuronectiformes containing 16 and 14 species respectively. In this area, the group comprising a lots of species was the family Gobiidae taking 13 species, and next groups were the families of Sciaenidae (6 species), Engraulidae (5 species) and Pleulonectidae (5 species). The dominant species was Engraulis japonicus which is 23.4 ％ in total indiyidual numbers, and subdominant species was Thryssa kummazensis which is 18.5%. The important species economically in the Saemankum area were Anguilla japonica, E. japonicus, T. kummalensis, Konosirus punctatus, Sardinella zunasi, Mugil cephalus, Argyrosomus argentatus, Pseudosciaena polyactis, Collichthys lucidus, Paralichthys olivuceus and Cynoglossus joyneri. The species of high frequency in this area from February to June every year were Anguilla japonica, E. japonicus, T. kammalensis, K. punctatus, S. zunasi, Coilia nasus, Syngnatuus schlegeli, P. polyactis, C. lucidus and Pholis fangi. Ophichthus rotundus, Repomucenus leucopoecitus and R. koreanus were Korean endemic species in the west coast of Chollabuk-do. On the other hand, Boleophthalmus pectinirostris was not found during this study, and Periophthalmus modertus, Tridentiger barbatus and Lophogobius ocellioauda sharply decreased in individual numbers in comparison to several years ago.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.132-144
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• 2022

The fish community in the Seomjin River-Seomjin River Estuary-Gwangyang Bay coast continuum was investigated three times from March 2019 to October 2019. The collected species at the eight sites during the survey period were 49 species belonging to 31 families, including two endangered species. According to Bray-Curtis similarities, observations were divided into four groups based on the fish community composition; two groups (group 1, 2) and two uncategorized groups (group 3, 4). ANOSIM based on spatial and temporal groupings indicated that the spatial differences in fish communities (R=0.398, P=0.001) were relatively more important than the temporal differences (analysis of similarities, R=0.273, P=0.002). In particular, there were significant differences between groups 1 and 2 (analysis of similarities, R=0.556, P=0.001), and similarity percentage analysis revealed that Argyrosomus argentatus (9.4%), Favonigobius gymnauchen (6.9%) and Konosirus punctatus (5.9%) contributed to these differences of fish assemblages for each group. The fish fauna distributed in the Seomjin River-Gwangyang Bay ecosystem were spatially divided and the number of species and number of individuals showed seasonal differences. This study could be a basis for understanding changes in the fish community and implementing conservation and management strategies on major species within a continuous environment of the river-estuary-ocean continuum.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.2
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• pp.142-152
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• 1995

The combined bottom trawl and hydroacoustic survey was conducted by using the training ship Oshoro Maru belong to Hokkaido University in November 1989-1992 and the training ship Nagasaki Maru belong to Nagasaki University in April 1994 in the East China Sea, respectively. The aim of the investigations was to collect the target strength data of fish school in relation to the biomass estimation of fish in the survey area. The hydroacoustic survey was performed by using the scientific echo sounder system operating at three frequencies of 25, 50 and 100kHz with a microcomputer-based echo integrator. Fish samples were collected by bottom trawling and during the trawl surveys, the openings of otter board and net mouth were measured. The target strength of fish school was estimated from the relationship between the volume back scattering strength for the depth strata of bottom trawling and the weight per unit volume of trawl catches. A portion of the trawl catches preserved in frozon condition on board, the target strength measurements for the defrosted samples of ten species were conducted in the laboratory tank, and the relationship between target strength and fish weight was examined. In order to investigate the effect of swimbladder on target strength, the volume of the swimbladder of white croaker, Argyrosomus argentatus, sampled by bottom trawling was measured by directly removing the gas in the swimbladder with a syringe on board. The results obtained can be summarized as follows: 1.The relationship between the mean volume back scattering strength (, dB) for the depth strata of trawl hauls and the weight(C, $kg/\textrm{m}^3$) per unit volume of trawl catches were expressed by the following equations : 25kHz : = - 29.8+10Log(C) 50kHz : = - 32.4+10Log(C) 100kHz : = - 31.7+10Log(C) The mean target strength estimates for three frequencies of 25, 50 and 100 kHz derived from these equations were -29.8dB/kg, -32.4dB/kg and -31.7dB/kg, respectively. 2. The relationship between target strength and body weight for the fish samples of ten species collected by trawl surveys were expressed by the following equations : 25kHz : TS = - 34.0+10Log($W^{\frac{2}{3}}$) 100kHz : TS = - 37.8+10Log($W^{\frac{2}{3}}$) The mean target strength estimates for two frequencies of 25 and 100 kHz derived from these equations were -34.0dB/kg, -37.8dB/kg, respectively. 3. The representative target strength values for demersal fish populations of the East China Sea at two frequencies of 25 and 100 kHz were estimated to be -31.4dB/kg, -33.8dB/kg, respectively. 4. The ratio of the equivalent radius of swimbladder to body length of white croaker was 0.089 and the volume of swimbladder was estimated to be approximately 10% of total body volume.