• Title, Summary, Keyword: Catch fluctuation

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Environmental Character and Catch Fluctuation of Set Net Ground in the Coastal Water of Hanlim in Cheju Island III. Environmental Character and Catch Fluctuation (제주도 한림 연안 정치망 어장의 환경특성과 어획량 변동에 관한 연구 III. 어획량변동과 환경요인)

  • KIM Jun-Teck;JEONG Dong-Gun;RHO Hong-Kil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.32 no.1
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    • pp.105-111
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    • 1999
  • To investigate the relationships between ocean environmental characteristics and thechange of the catch, we analyzed various environmental factors such as mean temperature, salinity, current vectors, lunar day and wind vectors from 1995 to 1996 and the catch fluctuation of Hanlim set net from 1994 to 1996. The results are as follow ; 1) The proportion of fishes caught in Hanlim set net is highest for horse mackere1 ($69.2\%$) and is followed by common mackerel ($18.4\%$), hair tail ($5.6\%$), squid ($2.7\%$) and rabbit fish ($1.4\%$) in order. Two peaks in the monthly catch appeared in June and October in the operation period of May- December. 2) The flow direction was northward in flood time and southeastward in ebb time around the Hanlim set net. Thus, the vortical mixing of sea water was active and continued for more than 3 hours. In addition, mean daily temperature was low due to the presence of middle and bottom water in offshore. Increase in salinity or high salinity of sea water provides a favorable condition for catches of fishes. Catches in the first quarter and the last quarter of the moon were larger than that in full moon and the last of the month. In particular, when south or southeasterly wind velocity reaches about 3$\~$6.5 m/s, the possibility of catches increases.

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Fluctuation of the Catch by the Set Net Fishery (정치망어업의 어획량변동에 관한 연구)

  • 장호영
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.23 no.4
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    • pp.177-183
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    • 1987
  • The catch by the set net fishery from 1971 to 1985 were analyzed in order to reveal its fluctuation characteristics. Generally, the catch increased from 16,787M/T in 1971 to 84,103M/T in 1985 and showed maximum in 1979 with 99,475M/T of catch. This trend was mainly related to the higher production of file fish which accounts for 64% of the total catch in 1979, and the change of catch statistical classification according to the revising of fishery law in 1976. It was also closely related to the variation of the sea water temperature in coastal area. The main fishing period of the set net fishery appeared from October to November. Catch of the set net fishery was led by that in the southern coast before 1976 and by that in the eastern coast from 1977 to 1980, the tendency changed irregular from 1981. Three groups of fishes could be distinguished by principal component analysis of the annual catch. A group showing steady decreasing tendency was composed of the fishes such as whiting, sand fish, hair tail and anchovy. The another group composed of small alaska pollack, round herring, goby, gizzard shad, sand lance and file fish revaled an increasing tendency. The other fishes did not show any annual tendency.

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Environmental Factors and Catch Fluctuation of Set Net Grounds in the Coastal Waters of Yeosu (여수연안 정치망 어장의 환경요인과 어황 변동에 관한 연구)

  • 김동수
    • 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.

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Influence of Sea Condition on Catch Fluctuation of Long Line for Common Octopus, Octopus Variddilis, in the Coastal Waters of Yosu (1) (여수연안 낙지주낙 어장의 해황과 어획 변동에 관한 연구(1))

  • 정정민;김동수
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.37 no.4
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    • pp.321-325
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    • 2001
  • In order to investigate the influence of sea condition on the catch fluctuation of long line for common octopus, octopus variabilis, the oceanographic factors, i. e., the water temperature, the salinity and the density in the coastal waters of Yosu from Jan. 11 to Jul. 25 in 1997, and compared with the catches of common octopus, octopus variabilis by long line. The results obtained summerized as follows; 1) The range of water temperature, salinity and density from Jan. to Jul. at the sea area were 4.1~$23.6^{\circ}C$, 31.7~34.5$\textperthousand$ and 21.30~27.81, respectively, and the catch of common octopus, octopus variabilis was high respectively at the temperature of 17~$-20^{\circ}C$, at the salinity of 33.0~33.5$\textperthousand$ and at the density of $\sigma$t 22.5~24.0. 2) The catch of common octopus, octopus variabilis was lowest from Jan. to Feb. and highest from May to June.

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Influence of Sea Condition on Catch Fluctuation of Long Line for Common Octopus, Octopus Variddilis, in the Coastal Waters of Yosu (1) (여수연안 낙지주낙 어장의 해황과 어획 변동에 관한 연구 (1))

  • 정정민;김동수
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.37 no.3
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    • pp.155-158
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    • 2001
  • In order to investigate the influence of sea condition on the catch fluctuation of long line for common octopus, octopus variabilis. the oceanographic factors. I .e., the water temperature, the salinity and the density in the coastal waters of Yosu from Jan 11 to Jul. 25 in 1997 and compared with the catches of common octopus, octopus variabilis by long line. The results obtained summerized as follows ; 1) The range of water temperature, salinity and density from Jan. to Jul. at the sea area were 4.1∼23.6℃. 31.7∼34.5‰ and 21.30∼27.81. respectively, and the catch of common octopus, octopus variabilis was high respectively at the temperature of 17∼20℃ at the salinity of 33.0∼33.5‰ and at the density of σ/sub t/ 22.5∼24.0. 2) The catch of common octopus. octopus variabilis was lowest from Jan. to Feb. and highest from May to June.

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A Study on the Assembling Factors and Catch Fluctuation of Fyke Net Grounds in the Coastal Waters of Yosu(I) -Relation between Catch Fluctuation of Common Mullet, Mugil Cephalus and Temperature and Salinity - (여수 연안 승망 어장의 환경요인과 어획변동에 관한 연구(I) -수온.염분과 어획량과의 관계 -)

  • 김동수;주찬순
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.37 no.2
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    • pp.71-77
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    • 2001
  • In order to find out the environmental factors influencing the catch of fyke nets in the coastal waters Yosu, the oceanographic factors, i.e., the waters temperature and the salinity were observed respectively from April to November in 1999, and each of them was compared with the catch of common mullet, Mugil cephalus by fyke net. The results obtained are summerized as follows : 1. The water temperature was ranged from 13.0 to $25^\circ$C and water temperature increased from April to August and decreased on September to November. 2. The range salinity in the fishing grounds was from 28.6 to 33.8$\textperthousand$, and salinity was high from April to June. From July, however, the salinity decreased to continue a low value still september. 3. The catches of common mullet caught by funnel net were the highest in may and the smallest in November. The ranges of optimum water temperature for the funnel nets fishing was 15.0 to $16.0^\circ$C, the ranges of optimum salinity for fishing varied between from 32.6 to 33.8$\textperthousand$.

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Effect of environmental conditions on the stock structure and abundance of the pacific saury, Cololabis saira in the Tsushima Warm Current region

  • Gong, Yeong;Suh, Young-Sang;Hur, Young-Hee
    • Proceedings of the Korean Aquaculture Society Conference
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    • pp.169-171
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    • 2004
  • Interannual and decadal scale body size of Pacific saury, catch and catch per unit effort were examined to investigate the environmental effects on the stock structure and abundance in the Tsushima Warm Current region. Interannual changes in thermal conditions are responsible for the different occurrence (catch) rates of sized group of the fish. Changes in body size due to environmental variables lead the stock to be homogeneous during the period of high abundance, while one of the reminder cohorts supports the stock during the period of low level of abundance. Migration circuits of two cohorts of saury stock are hypothesized on the basis of short life span and spatio-temporal changes in stock structure in normal environmental conditions. Changes in upper ocean structure and production cycles by the decadal scale climate changes lead changes in stock structure and recruitment, resulting in the fluctuation of saury abundance. Hypothesized mechanism of the effects of climate changes on the stock structure and abundance is illustrated on the basis of changes in thermal regime and production cycle.

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Effect of environmental conditions on the stock structure and abundance of the Pacific saury, Cololabis saira in the Tsushima Warm Current region (대마난류계 꽁치의 자원구조와 풍도에 미치는 해양환경의 영향)

  • Gong, Yeong;Seo, Yeong-Sang
    • Journal of Environmental Science International
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    • v.13 no.5
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    • pp.449-467
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    • 2004
  • Interannual and decadal scale changes in body size of Pacific saury, catch and catch per unit effort were examined to investigate the environmental effects on the stock structure and abundance in the Tsushima Warm Current region. Interannual changes in thermal conditions are responsible for the different occurrence (catch) rates of sized group of the fish. Changes in body size due to environmental variables lead the stock to be homogeneous during the period of high abundance, while one of the reminder cohorts supports the stock during the period of low level of abundance. Migration circuits of two cohorts of saury stock are hypothesized on the basis of short life span and spatio-temporal changes of the stock structure in normal environmental conditions. Changes in upper ocean structure and production cycles by the decadal scale climate changes lead changes in stock structure and recruitment, resulting in the fluctuation of saury abundance. Hypothesized mechanism of the effects of climate changes on stock structure and abundance is illustrated on the basis of changes in thermal regime and production cycle.

CPUE standardization of Pacific bluefin tuna caught by Korean offshore large purse seine fishery (2003-2016) (우리나라 대형선망어업에서 어획된 태평양참다랑어의 CPUE 표준화(2003-2016))

  • LEE, Sung Il;KIM, Doo-Nam;LEE, Mi-Kyung;JO, Heon-Ju;KU, Jeong-Eun;KIM, Jung-Jin
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.54 no.2
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    • pp.116-123
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    • 2018
  • Pacific bluefin tuna (Thunnus orientalis) has been mostly caught by the Korean offshore large purse seine fishery in Korean waters. The annual catch of Pacific bluefin tuna caught by the offshore large purse seine fishery in Korean waters showed less than 1,000 mt until the 1990s except for 1997. The catch sharply increased to 2,401 mt in 2000 and recorded the highest of 2,601 mt in 2003, but the catch has generally decreased with a fluctuation thereafter. The main fishing ground of Pacific bluefin tuna of this fishery is formed around Jeju Island. However, it expanded to the Yellow Sea, the coastal of Busan, and the East Sea, which depends on the migration patterns of Pacific bluefin tuna by season. The CPUE standardization of Pacific bluefin tuna was conducted using Generalized Linear Model (GLM) to assess the proxy of the abundance index. The data used for the GLM were catch (weight), effort (number of hauls), catch ratio of Pacific bluefin tuna, moon phase by year, quarter and area. The standardized CPUE from 2004 to 2011, except for 2003 and 2010, showed a steady trend, and then increased until 2014. The CPUE in 2015 decreased, and in 2016 was higher than that in 2015. The result of GLM suggests that the effect of the catch ratio of Pacific bluefin tuna is the largest factor affecting the nominal CPUE.

Relationship between Fishing Condition of Common Squid and Oceanic Condition in the East Sea (동해에서의 오징어 어황과 해황과의 관계)

  • Cho Kyu-Dae;Kim Sang-Woo;Kang Gi-Hong;Lee Chung-Il;Kim Dong-Sun;Choi Yun-Sun;Choi Kwang-Ho
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.10 no.1
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    • pp.61-67
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    • 2004
  • This study described relationships between fluctuation of fishing conditions for common squid and oceanic conditions in the East Sea from 1990 to 1999. Annual catches of common squid have been higher since the late 1980s compared to the period of the late 1970s to the mid-1980s. These catches fluctuations might be related to the effect of regime shifts. Monthly catches of common squid appear the timing of a large catch from September to December and a poor catch from March to May. The monthly catches are also the highest in October and are the lowest in April. Annual stable fishing grounds for coefficient of variation below 1.0 are formed in waters around Guryongpo and Ullung Island Based on optimum water temperature for catch, $16^{\circ}C$, optimum water depth for catch shallow going north. It indicates that the optimum water depth of fishing work different of each area Fishing ground formation and horizontal water temperature appear the minimum $10{\sim}14^{\circ}C$ in April, the maximum $10{\sim}20^{\circ}C$ in October. If seem, that seasonal fluctuation of fishing ground is related to the extension of the Tsushima warm current in the East Sea.

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