• Title, Summary, Keyword: Catch fluctuation

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Dominant causes on the catch fluctuation of a set net fishery in the mid-south sea of Korea (남해 중부해역 정치망어업 어획량 변동의 원인)

  • Kim, Heeyong;Song, Se Hyun;Lee, Sunkil;Kim, Jong-Bin;Yoo, Joon-Taek;Jang, Dae-Soo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.49 no.3
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    • pp.250-260
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    • 2013
  • The annual and monthly fluctuation in the species composition and the catch abundance of dominant species were analyzed using the daily sales slip catch data by a set net in the offshore waters off Dolsan Island in Yeosu from March 2004 to December 2011. Mean catch from 2004 to 2011 is 372M/T and the maximum and the minimum catch are 526 M/T in 2005 and 27 2M/T in 2009, respectively. The dominant species were Engraulis japonicus mainly in spring and Scomberomorous niphonius in Autumn and therefore the set net catch that is dominated by S. niphonius's catch was much higher in autumn than in spring. Through comparative analyses for the environmental factors to the annual catch fluctuation, it is revealed that the water temperature variation affected the recruitment property of S. niphonius to the fishing ground but the effect of typhoon on the catch fluctuation was not distinct. Furthermore, the big blooming event of jellyfish, particularly Nemopilema nomurai, that occurred in 2009 showed a tendency of faster appearance and later extinction until December. The occurring characteristic of N. nomurai became a direct cause that brought about the lowest total catch in 2009 since the dominant species catch of the set net fishery was concentrated mostly in Autumn.

Catch fluctuation of the Pound Set Net According to Tide Age in the Coastal Waters of Jeju (제주 연안의 소대망에서 조석에 의한 어획량 변동)

  • Kim, Byung-Yeob;Seo, Du-Ok;Lee, Chang-Heon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.42 no.1
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    • pp.83-88
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    • 2009
  • The purpose of this paper is to obtain the fundamental data on the catch fluctuation in the pound set net according to the tide age from the catch recorded from the year 1997 to 2004 in the coastal waters of Guideok, Jeju. Total catch by the pound set net had a little connection with the tide age. During increasing tide, total catch were reduced slightly from the neap tide to the high tide while there seemed to be a little sign of rise in the total catch until decreasing tide. But in the relation between the catches and the tide age, the level of the correlation coefficient chosen at $p{\le}0.05$ was not significant. Therefore, the catch of the pound set net seemed not to be influenced by the tide age. In addition, CPUE at the high tide was higher than that at the neap tide. When the catch per operating frequency was graded in the order under 50 kg, 50-100 kg and 100-200 kg, the frequency rate by the pound set net was 38%, 19% and 19%, respectively.

Catch fluctuation of the rectangular set net according to the tide age in the coastal waters of Jeju (제주연안 각망의 조석에 의한 어획량 변동)

  • Lee, Chang-Heon;Choi, Chan-Moon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.44 no.2
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    • pp.112-119
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    • 2008
  • The fundamental data on the catch fluctuation in the rectangular set net according to the tide age were developed based on the catches recorded from the year 1986 to 2004 in the coastal waters of Hamdeok, Jeju. Total catch by the rectangular set net had a deep connection with the tide age. In particular, during increasing tide, total catch were reduced gradually from the neap tide to the high tide. As it turned out, the slope of total catch declined by degree and showed a correlation coefficient of determination of 0.76. On the contrary, in the case of decreasing tide, there was little sign of rise in total catch. In particular, large catch seemed to occur at the next tide to the neap tide. In the relation between the catch and the tide age, the level of the correlation coefficient chosen at $p{\leq}0.05$ decreased in the order rabbitfish(-0.84) and horse mackerel(-0.71), while the significance of other dominant species were not selected.

A Study on the Sea Condition and Catch Fluctuation of Anchovy Gill Net in the Coastal Waters of Yosu (여수 연안 멸치 자망 어장의 해황과 어획량의 변동)

  • Joo, Chan-Soon;Kim, Yong-Ju;Kim, Dong-Soo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.34 no.2
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    • pp.159-164
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    • 1998
  • In order to investigate the relation between the environmental factors influencing on the fluctuation of fishing condition and the catch of anchovy in gill nets in the coastal waters of Yosu, five oceanographic factors, i.e., water temperature, salinity, chlorophyll-a and the catch of anchovy in gill nets are observed from June 6 to August 12 in 1993. The results obtained are summerized as follows: 1) The water temperature ranged from 16.$0^{\circ}C$ to 22.6$^{\circ}C$ and the salinity from 30.13$\textperthousand$ to 33.65$\textperthousand$. the water temperature and salinity showed no significant influence on the catch of anchovy, but the catch did not expose high values in low temperature and salinity. 2) The catch of anchovy increased with the amount of chlorophyll-a. It is therefore emphasized that the amount of chlorophyll-a is the greatest one of environmental factors influencing on the catch of anchovy.

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Environmental Factors and Catch Fluctuation of Set Net Grounds in the Coastal Waters of Yosu - 4 . Water Temperature and Salinity and Fluctuation of Catch - (여수연안 정치망어장의 환경요인과 어황변동에 관한 연구 - 4 . 수온 염분과 어획량 변동 -)

  • Kim, Dong-Su;Rho, Hong-Gil
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.32 no.2
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    • pp.125-131
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    • 1996
  • In order to investigate the relation between the environmental properties and the catch fluctuation of set net fishing grounds located in the coastal waters of Yosu, oceanographic observations on the fishing grounds were carried out by the training ship ofYosu Fisheries University from January, 1990 to September, 1992, and the data obtained were compared with the catch data from the joint market ofYosu fisheries cooperative society from 1984 to 1993. The resuItes obtained are summerized as follows : 1. The ranges of water temperature and salinity in the fishing ground was 7.0 to $27^{\circ}C.$and 26.6 to 33.2${\textperthousand}$, and water temperature increased from March to August and decreased from September to February of following year. 2. The salinity in the fishing grounds was relatively high without significant changes from November to June of the following year. From July, however, the salinity decreased to continue a low value till September and then increased. The salinity in the fishing ground was dominated mainly by the precipitation and its variation was large at the north entrance of set net fishing ground, influenced greatly by the land waters from the river of Somjin, but small in the offshore of the fishing grounds. 3. The fishes caught by the set nets were arranged in order of catch as follows; Spanish mackerel> Horse mackerel > Sardine > Anchovy > Hair tail. The catches of Anchovy and Sardine were high in April to May and those of Hair tail in June to July, but Spanish mackerel and Horse mackerel were caught for whole period of fishing. Spanish mackerel was caught most in September and least in April and their means were largest in August and smallest in June. 4. The ranges of optimum water temperature for fishing by the set nets was 13.5 to $25^{\circ}C.$, and in the ranges the catches increased with increasing temperature. The ranges of optimum salinity for fishing varied between 25.0 and 32.0${\textperthousand}$.

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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 (2) (여수연안 낙지주낙 어장의 해황과 어획 변동에 관한 연구 (2))

  • 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.159-162
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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 wind direction, the wind speed, the age of moon and ebb tide and flood tide 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 catch of common octopus was highest in wind direction from SE and lowest in that from NW. The catch was highest at the wind speed of 2m/sec and decreased with increasing speed, over 2m/sec. 2) The catch of common octopus was highest at the day of neap tide and lowest at the mid day, from neap tide to spring tide. More strictly the catch was higher during days at which the current became rapid than during days at which the current became slow. The catch was higher always at flood tide than at ebb tide in all the days investigated and highest with in one hour from ebb tide.

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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 (2) (여수연안 낙지주낙 어장의 해황과 어획 변동에 관한 연구(2))

  • 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.326-330
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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 wind direction, the wind speed, the age of moon and ebb tide and flood tide 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 catch of common octopus was highest in wind direction from SE and lowest in that from NW. The catch was highest at the wind speed of 2m/sec and decreased with increasing speed, over 2m/sec. 2) The catch of common octopus was highest at the day of neap tide and lowest at the mid day, from neap tide to spring tide. More strictly the catch was higher during days at which the current became rapid than during days at which the current became slow. The catch was higher always at flood tide than at ebb tide in all the days investigated and highest with in one hour from ebb tide.

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Variation of fisheries conditions of mackerel (Scomber japonicus) fishing ground for large purse seine fisheries (대형선망어업에 있어서 고등어 (Scomber japonicus) 어장의 어황변동)

  • Lee, Haet-Nim;Kim, Hyung-Seok
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.2
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    • pp.108-117
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    • 2011
  • In order to offer data about fisheries resources management and prediction of catch on large purse seine fisheries, the fluctuation of the fisheries condition and distributions of fishing ground for mackerel were analysed with monthly catch data for 1990.2009. The overall catch has decreased to about 70% since 1997, with approximately 70% of the mackerel (Scomber japonicus) catch and monthly fluctuations showing a similar pattern. Monthly distribution of fishing ground is like distribution of mackerel in large purse seine fishery. The main fishing grounds are near Jeju Island and the Yellow sea with the main fishing season existing between October to December. The catches fluctuations and distribution of fishing ground were related to the effect of regime shifts. Therefore, in order to prediction of catch on large purse seine fisheries should be studied these relationships.

Environmental Factors and Catch Fluctuation of Set Net Grounds in the Coastal Waters of Yeosu 3. The Quantity of Phytoplankton and Catch Fluctuation. (여수연안 정치강어장의 환경요인과 어항변동에 관한 연구 3 . 기초생산자의 출현과 어획량의 변동)

  • Kim, Dong-Soo;Rho, Hong-Kil
    • 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.

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