• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.129-139
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• 2002

Fish distribution characteristics are essential to assess and estimate fisheries resources in a particular area. The primary goal of this study is to determine the distribution characteristics by the bottom trawling in the Yellow Sea west of South Korea. The surveys were carried out between 33$^{\circ}$00'N~37$^{\circ}$00'N latitude and 124$^{\circ}$00'E~126$^{\circ}$00'E longitude at EEZ(Exclusive Economic Zone) of Korea in Yellow Sea on May and August, 1999 and April, 2000. The ships used in this survey were the R/V Chung-kyeong(G/T 300) and R/V Dong-baek(G/T 1,050) of Yeosu National University. The results obtained can be summarized as follows 1. From the trawl data the fisheries resources are seriously decreasing through most of the species(about more 50%) have been appeared only one time at the bottom trawl on April, 2000. The total fish species caught by the trawl net during the 3 times survey were 106 species and a few species(dominant species) of these occupied 50~90% of the quantity of the total quantity by number or by weight. Among the dominant species the tanaka's snailfish was recorded to be the most dominant species in the survey area. The fish species in the Yellow Sea were clustered according to the regions. They clustered in two or three partes to the south-north direction in the spring season and clustered in two parts to the on-off shore direction of the shore in the summer season. Most of the fish caught at the the trawl net with cover-net(30.3mm) were small sized. They were shorter than 15 cm in length and the extruding rate of the cod-end which was 60mm mesh size ranges about 90%. 2. The densities of the number and weight per unit volume derived from the total catches sampled in April, 2000 survey were $1532.2{\times}10^{-6}fish/m^3$ and $39.55{\times}10^{-6}kg/m^3$, respectively. 3. The density variation of fish population between 1999 and 2000 showed a slight tendency to increase.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.51-63
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• 2013

To assess the effect of environmental factors on the sustainability of cultured production shellfish, we investigated the habitat characteristics of tidal flat (Namhae-po in Taean). We measured the physiochemical parameters (temperature, salanity, pH, dissolved oxygen and nutrients) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several site of tidal flat to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain size for research area of tidal flat were similar at the ratio of silt and clay in comparison with the other site of it. The C/N ratio was more than 5.0, reflecting the range arising from the mix of marine organism and organic matter. The C/S ratio (about 2.8) showed that survey area had anoxic or sub-anoxic bottom conditions. The enrichment factor (Ef) and index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. Adult surf clam (Mactra veneriformis) density was highest at St. 2 (middle part of the Namhae-po), on the other hand, surf clam spat density was highest at St. 3 (lower part of the Namhae-po). Heavy rain, terrigenous suspended clay with fresh water from neighboring agricultural land, and severe high air temperature during summer could be thought as detrimental causes of spat and adult mortality in Namhae-po tidal flat. We suggested that the growth of shellfish in the tidal flat was effected by the various environmental conditions, so an improvement in the cultured method was needed.

• Journal of Aquaculture
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• v.8 no.1
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• pp.47-58
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• 1995

Field studies on the seasonal succesion of phytoplankton population were carried out at the 25 stations of the breeding ground in Kogum-sudo, Southern coast of Korean peninsula in Feburuary, April, August and October, 1993. Sixty four species belonging to 40 genera were identified. Predominant species were mainly centric diatoms throughout the four seasons, two centric diatoms, Skeletonema costatum and Thalassiosira sp. and a pennate diatom, Thaiassionema nitzschioides in the winter; two pennate diatoms, Thaiassionema nitzschioides and Asterionella kariana, and especially a dinoflagellate, Heterocapsa triquetra (station 10) in the spring, two centric diatoms, S. costatum and Chaetoceros diadema in the summer; and a centric diatom, Rhizosolenia alata and a pennate diatom, Bacillaria paxillifer in the fall. The main red tide organisms in the breeding ground were dinoflagellates, Prorocentrum dentatum, P. minimum, P. triestinum, Ceratium furro, Gymnodinium sanguineum, Noctiluca scintillans, H. triquetra, Scrippsiella trichoidea and a diatom S. costatum in the Kogum Sudo. Seasonal phytoplankton cell numbers were in a wide range between $8.8\times10^3$ cells/l and 1.4\times10^6$ cells/l; The seasonal average cell numbers were $12.2\times10^4\pm5.9\times10^4$ cells/l $(mean\;\pm\;standard\; diviation)$ in the winter, $3.3\times10^4\pm1.4\times10^4$ cells/l in the spring, $48.4X10^4\pm40.0\pm10^4$ cells/l in the summer, and $3.6\times10^4\pm1.9\times10^4$ cells/l in the fall, respectively.