• 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.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.350-351
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• 2000

선망어업에 의해 어획되는 다랑어 어군은 연승어업과는 달리 주로 표층에서 유영, 이동, 또는 섭이하는 가다랑어나 황다랑어 무리로 이들의 분포 특성을 감안하면, 해수의 표층수온 등 해양환경 변화는 선망어업의 어획량, 단위노력당어획량 및 종조성등에 상당한 영향을 미칠 것으로 추정된다. 한편, Lehodey (1997)는 미국의 선망어획자료를 이용하여 엘니뇨가 가다랑어의 분포에 직접적인 영향을 미친다고 발표한 바 있다. 본 논문에서는 국립수산진흥원에서 1995-1998년간 한국 다랑어 선망어선으로부터 수집한 어획 자료를 이용하여 최근의 해양환경 변동에 따른 한국 선망어업의 어장변동 및 조업특성에 대해서 서술하고자 한다. (중략)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.133-142
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• 1990

For the purpose of investigation of demersal fisheries resources of the East China Sea, joint research between Hokkaido University and National Fisheries University of Pusan was carried out during the period from November 5 to November 12 in 1989. This joint research is due to continue for the next three years. In this report, the authors analyzed the catch of 24 draughts of trawl operating by the Oshorumaru of the training ship of Hokkaido University in the north area of the East China Sea, in order to hold the present condition of the demersal resources. The specimens collected were composed of 76 species of fishes, 6 of mollusca and 7 of crustacea. And the main species of the large catch were Raja kenojei, Zeus faber, Miichthys miiuy, Collichthys lucidus, Dentex tumifrons, Carangoides caeruleopinnatus, Trachurus japonicus, Parastromateus niger, Trichiurus leptulus, Scomberomorus niphonius, Pampus argenteus, Pampus echinogaster, Psenopsis anonala, Liparis tanakai, Thammaconus modestus, Tadarodes pacificus, Loligo edulis, and Portunus trituberculatus. Especially, Trichiurus leptulus, Pampus agrenteus and Thammaconus modestus had different modes of classes of body size individually, with changing of fishing ground. But, Tadarodes pacificus, Loligo edulis and Portunus trituberculatus were caught the maxed sizes of body individually in the same ground.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.239-252
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• 1981

The East China Sea is an important region as nursery and spawning grounds for pelagic fishes such as jack mackerel, common mackerel etc. , and thus constitutes a major fishing area for purse-seine fishery. The environment surrounding in this region is under the influence of the Yellow Sea Cold Water, China Coastal Water and Kuroshio Current. The purpose of this study was to clarify the effects of oceanographic conditions and thermal fronts on the formation of the fishing grounds for the mackerels in the East China Sea. Through the analyses of fisheries statistics during 1968-1976 and temperature data, the following facts are found: 1) Approximately $70\%$ of the total mackerel(common) catches appeared to be come from the Tsushima Current region which includes Sakai coast of the Japan Sea, eastern Tsushima and Shirase Island, and Jeju Island of Korea. This area covers only about $8\%$ of the East China Sea. 2) Main fishing grounds for the jack mackerel are also centered around the area of southwestern Goto, Shirase and eastern Tsushima Island where the catches accounted for about $54\%$ of the total jack mackerel catches. 3) Fluctuations in annual catches are relatively small in the Tsushima Current region, compared to other regions such as Yellow Sea, southwestern coast of Kyushu and mid-western part of the East China Sea, where the fisheries yields varied considerably due to unstable fishing conditions. 4) It appears that the fishing grounds for the jack mackerel are mainly distributed along the warmer region ($15-20^{\circ}C$) of the thermal front, and those for the common mackerel are in somewhat colder region ($13-16^{\circ}C$) in the Tsushima Current.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.15-30
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• 1998

The variation of the catches of Skipjack(Euthynnus pelamis) and the relationships between the SST and the fishing ground is examined using the catches data of skipjack obtained by Iwawada Fisheries Cooperative of Chiba Prefecture in Japan from 1982 to 1988. The annual mean catch for Skipjack was 151,375.1kg. the annual fluctuation of catch was that the catch in 1984 was increasing, but it was decreased less than 50% in 1985, and was repeated after being a little recovered in 1986, and it was recovered with the level of 1984 in 1988. The fluctuation of catch for Skipjack in every fishing term is that daily mean catch of the primary fishing term (January, February and March) is 894.6kg, but the middle fishing term(April and May) more than four times of the primary fishing term is 3,666.0kg, the last fishing term(June and July) was decreasing at 767.9kg and the fishing ground gradually becomes extinct. The annual mean SST in fishing ground was an extent of from $19.0^{\circ}C$ to $20.2^{\circ}C$, the mean SST of every year except 1983 was from $19.0^{\circ}C$ to $19.9^{\circ}C$. It is said that the optimum SST of Skipjack in Sotobo sea area is the degree of $19.0^{\circ}C$. Therfore, the thing which will guess the time and the location appeared the optimum SST is the very important factor to operate efficiently. About the extent of SST in fishing ground, it was from $17.0^{\circ}C$ to $19.0^{\circ}C$ on March, from $17.5^{\circ}C$ to $20.5^{\circ}C$ on April and from $17.5^{\circ}C$ to $23.5^{\circ}C$ on May, which the extent of SST was gradually larger and larger, on June from $21.0^{\circ}C$ to $23.5^{\circ}C$, fishing ground was formed only the degree of SST more than $21.0^{\circ}C$.

• Korean Journal of Ichthyology
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• v.31 no.3
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• pp.172-177
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• 2019

Seasonal fluctuation in abundance and species composition of fish in coastal waters off Dolsan island were investigated using seasonal samples collected by an otter trawl in 2012. A total of 4,848 fishes were sampled and classified into 52 species, 29 families, and 7 orders. The dominant species was Leiognathus nuchalis (2,786 individuals, 57.5%), Amblychaeturichthys hexanema (164 individuals, 3.4%), and Ilisha elongata (141 individuals, 2.9%). The highest number of individuals was found in summer (2,174 individuals), while the lowest number of individuals was found in winter (321 individuals). The diversity index was the highest in spring (H'=3.06) and the lowest in summer and fall (H'=1.77). Temperature was the principal factor to determine the collected number of individuals (r=0.94) and the number of species (r=0.83).

• Korean Journal of Ichthyology
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• v.32 no.3
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• pp.148-159
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• 2020

This study investigated the seasonal and inter-annual changes in vertical distribution and size spectrum of walleye pollock, Gadus chalcogrammus inhabiting middle eastern coast of Korea (hear after pollock). Pollock was distributed between 50 m and 600 m depth range, and body size (total length) ranged from 16.6 cm to 81.5 cm. The trends of population body size were increased in autumn and winter and decreased in spring and summer. Vertical distribution of pollock showned depth-dependent patterns with distributing smaller individuals mainly in the upper layer (shallower depth), while larger fish in deeper habitats. Those patterns in vertical distribution of pollock population is probably due to be the results of energy-saving strategy, metabolic effects, and changes in prey selections according to pollock growth, derived from spatial and temporal changes in oceanic condition in habitat grounds. When water temperature in upper layer were increased and that of below thermocline depth became decreased in 2017, the ratio of smaller (<35 cm) and larger (≥35 cm) individuals was biased toward larger fishes, extending their distribution into shallow depth, and consequently main fishing ground was formed in far from coastal area. In addition, the ratio of smaller individual distributing between 100~300 m was increased with decreasing temperature gradient between below thermocline and bottom layer. Changes in spatial and temporal distributions of pollock population likely be related with vertical and horizontal changes in oceanic conditions and, consequently food supplies.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.2
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• pp.97-103
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• 2004

This paper presents a general overview of the Korean stick-held dip net fishery for Pacific saury operated in the North Pacific Ocean since 1985. Annual catches, annual centroids distribution of fishing ground, and optimum fishing temperatures were compared between the periods before and after the new Korea-Japan bilateral fishery arrangement established in 1998. Fishing usually began in May and ended by December, during which major catches were taken in the months September~November before the bilateral fishery arrangement between Korea and Japan, whereas in August~October after the arrangement. It was observed that after the arrangement the centroids of fishing ground was shifted from the usual fishing area off the east coast of Japan to the east of South Kuril Islands, 45$^{\circ}$N and 151$^{\circ}$E. Optimum fishing temperatures appeared to be different by month ; 12.5~14.4$^{\circ}C$ in May, 12.0~14.2$^{\circ}C$ in June, 11.4~13.9$^{\circ}C$ in July, 11.4~15.9$^{\circ}C$ in August, 12.9~16.9$^{\circ}C$ in September, 12.7~17.3$^{\circ}C$ in October, 13.1~17.6$^{\circ}C$ in November, and 15.0~19.1$^{\circ}C$ in December. A total of 13 species were caught during scientific observation periods but the target species, Pacific saury, accounted for about 99.9% of the total catch. Although there was no difference in fishing days between those vessels equipped with the sonar and those without sonar, number of set, total catch, and CPUE of those with sonar were higher than those without sonar by 13%, 26%, and 12%, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.4
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• pp.238-246
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• 1991

In order to make clear the mechanism forming the fishing ground of anchovy drag net in connection with water temperature, catch and oceanographic data for the years of 1970-1988 in the Southern Sea of Korea were analyzed. The annual catch of anchovy drag net was about 21,000M/T in 1970 but it was increasing largely so far 100,000M/T in recent years. The fishing season of anchovy drag net is the whole year beside the prohibition season established in aims to protect the spawning group of anchovy, and then in the best season of the period from July to December, the fishing ground is made up in the coastal area joining Yosu, Namhaedo and Bangeojin. There were some evidences that the fishing condition was controlled by the oceanographic condition, especially water temperature, that is, when there was large difference in water temperature between the south area of the Eastern Sea and the west area of the southern Sea and the thermocline is formed strongly in the larger less than 20m, the fishing condition was good. On the other hand, there was a very effective correlation between the catch(X) of anchovy spawning group in Spring by other fishing gears, mainly drift net and that(Y) of the little size of anchovy by drag net in Autumn, expressed by the relative equation, Y=62,246+1.3X, r=0.63.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.341-348
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• 1983

The Relationship between the distribution of the fishing grounds of anchovy and the oceanographic conditions in the Korean Waters are investigated by using the data of the catch of anchovy by the gill net fishery (Fisheries Research and Development Agency, 1969-1982) and the oceanographic observation data (Fisheries Research and Development Agency, 1979). The main fishing ground of anchovy by the gill net fishery was five fishing areas located in the adjacent seas of Sockcho, Kuryong-po, Kijang, Keoje island and Chungmu, the area of which occupies no more than $20\%$ of all fishing grounds, and it appeared that about $80\%$ of mean catches of fourteen years was concentrated in this area. The main fishing periods were from April to June and October to November. The coefficient of variation of the catch for the main fishing ground were from 0.3 to 0.6 and the condition of all fishing ground was generally stable. The mean CPUE was 81.2 kg/set at the main fishing ground. The annual mean catch of anchovy by the gill net was the smallest in February and the largest in May through a year. It was found that the fluctuation is related to the expansion and reduction of the isothermal line of $10^{\circ}C$.