• 한국수산과학회지
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• 제38권3호
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• pp.196-204
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• 2005

The horizontal and vertical distribution of yellowfin tuna, Thunnus albacares (Bonnaterre) and bigeye tuna, Tunnus obesus (Lowe) in relation to oceanic conditions such as thermal structure produced during El Nino/La Nina episodes were analyzed on the basis of data sets for the catches and efforts from the Korean tuna longline fishery and for the oceanographic observations from the NOAA during 1982-2002 in the tropical Pacific. The high density of fishing ground appeared in the western Pacific ($5^{\circ}N-5^{\circ}S,\;160^{\circ}E-180^{\circ}W$) for yellowfin tuna and in the eastern Pacific ($5^{\circ}N-15^{\circ}S,\;130^{\circ}W-100^{\circ}W$) for bigeye tuna. yellowfin and bigeye tunas were mainly distributed at the 110-250 m layer and 245-312 m layer, respectively, in the western Pacific. However, in the eastern Pacific, they were mostly caught at the 116-161 m and 205-276 m layer for yellowfin tuna and bigeye tuna, respectively. It can be suggested that bigeye tuna be distributed in the deepest layer among tunas and show a vertical size stratification. It was observed that during the El Nino events the main fishing ground of yellowfin tuna shifted from the western Pacific toward the eastern Pacific. In the eastern Pacific which showed a higher density of bigeye tuna, the vulnerability of bigeye tuna caught by deep longline increased during the El Nino events due to deepening of thermocline layer and a more intensively distribution of the fish schools in the lower layer of thermocline during the El Nino events.

• 한국수산과학회지
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• 제22권2호
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• pp.86-94
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• 1989

Yellowfin and bigeye tunas have been targeting and the most important species for the Korean tuna longline fishery in the Indian Ocean. This study is aimed to analyse the fishing efficiency of the regular and the deep longlines and the vortical distribution of tunas, and the weight composition by fishing depth based on the data from Korean tuna longline fishery from 1973 to 1980 and from 1984 to 1986 in the Indian Ocean. It was found that the deep longline gear on bigeye tuna was significantly different from the regular longline gear on yellowfin tuna in the whole Indian Ocean. Yellowfin tuna and billfishes were chiefly distributed at the shallow layer and bigeye at the deep layer. The weight composition of yellowfin and bigeye tunas by depth showed that the deeper the depth, the larger the bigeye distributed.

• 수산해양기술연구
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• 제47권4호
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• pp.390-402
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• 2011

A preliminary study on species composition of a Korean purse seine catch landed at cannery was conducted in April 2011. In the cannery, all tuna catch are sliding through a sorting grid panel that filters and drops fish in the buckets by size class (above 9kg, 3.4-9kg, 1.8-3.4kg, 1.4-1.8kg and below 1.4kg). In cannery processing, species sorting was made for skipjack tuna and yellowfin tuna only from catches greater than 3.4kg during filtering but not for bigeye tuna because of difficulties in species identification between bigeye tuna and yellowfin tuna under frozen state. As no species identification was carried out for catch groups less than 3.4kg in the cannery process, this study focused on sorting out skipjack tuna and yellowfin tuna from these groups and then identifying bigeye tuna from all size groups of yellowfin tuna. Using the mixture rate of species obtained from the samples taken, species composition of the landed catch was estimated. As results, cannery research showed 95% for skipjack tuna, 3% for yellowfin tuna and 2% for bigeye tuna in species composition, while vessel logbook data represented 96%, 3% and 1% for skipjack tuna, yellowfin tuna and bigeye tuna, respectively. The proportion of bigeye tuna identified in the cannery was slightly higher than shown in logbook data by 1%.

• 한국수산과학회지
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• 제30권5호
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• pp.719-729
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• 1997

눈다랑어와 황다랑어의 먹이의 종류와 섭이 습성을 비교하기 위하여 서부 열대 태평양에서 연승어업으로 어획된 이들 다랑어의 위내용물을 조사하였다. 눈다랑어와 황다랑어의 먹이는 주로 어류, 두족류, 갑각류이었다. 이들 두 종의 다랑어에서 동정된 먹이생물의 총 종수는 어류가 15종, 갑각류 6종 그리고 두족류가 1종이었으며 그 중 가장 중요한 먹이는 샛비늘치류인 Myctophum sp였다. 황다랑어와 눈다랑어의 먹이를 분석해본 결과 먹이의 종류에 있어서는 두 종간에 큰 차이가 없었으며 이것으로 보아 같은 해역에 서식하는 다랑어류는 먹이 습성이 유사함을 알 수 있었다. 그러나, 먹이 가운데 몇몇 종 (Myctophidae, Alepisauridae, Oplophoridae, Gammaridae, and Onychoteuthidae)의 경우 그 중요도에 있어서 두 다랑어간에 현저한 차이를 보였다.

• 수산해양기술연구
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• 제47권4호
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• pp.344-355
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• 2011

We conducted experiments to compare the catch rate of bigeye tuna and yellowfin tuna between circle hooks and straight shank hook in the Korean tuna longline fishery at the eastern and central Pacific Ocean from 2005 to 2007. We analyzed difference of fork length, survival and hooking location between a circle hook and a straight shank hook for both tunas, respectively. There was no difference in the mean fork length size of yellowfin tuna caught on the two type of hook but bigeye tuna was significant. In case of survival, there was no difference between two hook type, but the difference of hooking location was significant for both species. We also analyzed to find determinants of both tunas catch rate using generalized linear models (GLMs) which were used latitude, longitude, year, month, depth, hook type, bait type and so on as independent variables. Spatial factors, latitude and longitude, and temporal factors, year and month, affected catch rate of bigeye tuna and yellowfin tuna. And also, depth such as a marine environment factor was influenced on catch rate.

• 수산해양기술연구
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• 제44권3호
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• pp.194-206
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• 2008

This study standardized catch per unit effort(CPUE) of the Korean longline fishery, which has been used to assess the status of stock as an index of abundance, for bigeye and yellowfin tunas in the Indian Ocean. The Generalized Linear Model(GLM) was used to analyze the fishery data, which were catch in number and effort data collected each month from 1971 to 2007 by $5\;{\times}\;5$ degree of latitude and longitude. Explanatory variables for the GLM analysis were year, month, fishing area, number of hooks between floats(HBF), and environment factors. The HBF was divided into three classes while the area was divided into eight subareas. Although sea surface temperature(SST) and southern oscillation index(SOI) were considered as environmental factors, only SST was used to build a model based on statistical significance. Standardized CPUE for yellowfin tuna showed a declining trend, while nominal CPUE for the species showed an increasing trend.

• 수산해양기술연구
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• 제22권4호
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• pp.21-31
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• 1986

The author investigated the relation between the catches of tuna species and the distribution of horizontal mean temperature at the Jepth of 10m and of vertical temperture sections in the different fishing grounds, using the date of catches in 1980, showing a relative good ones during six years from 1975 to 1980, and of oceanographic observations. Yellowfin and bigeye are mainly caught in South Equatorial Current regions including equatorial upwelling region in 5$^{\circ}$N to 5$^{\circ}$S, and albacore is mainly caught in Subtropical region in 20$^{\circ}$5 to 40$^{\circ}$5. The good fishing grounds of yellowfin and bigeye are made in the depth layer of 100 m to 250 m and temperature of 15$^{\circ}$C to 26$^{\circ}$C having a smooth gradient of thermocline in the Central Pacific between 180$^{\circ}$ and 1500W. But albacore is caught well in which the temperature of thermocline ranges from 100e to 25$^{\circ}$C and its gradient very smoothly. Approaching to the American Continent, the catches of yellowfin and big eye decrease because the thermocline becomes shallower and steeper at Eastern Pacific Region between 1500 and 800W.

• 한국수산과학회지
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• 제29권2호
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• pp.197-207
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• 1996

한국 다랭이 선망어선의 유목군 조업 비율은 최근 까지 점차 감소 추세에 있으며 $1990\~1995$년간의 유목군 어획 비율은 전체 어획량의 $34.6\%$로 선망어업 초기와 비교해 볼 때 상당히 낮았다. 어획 어종의 조성에서는 유목군 및 부상군 조업에서 다같이 가다랭이가 가장 많이 어획되었고 그 다음 황다랭이 그리고 소량의 눈다랭이가 어획되었다. 황다랭이의 어획 비율은 부상군 조업이 유목군 조업보다 높았다. 승선 조사 시의 유목군 조업의 어획 어종의 조성은 가다랭이 $60\%$, 황다랭이 $38\%$, 눈다랭이 $2\%$로 조업 실적 자료보다 가다랭이는 낮았고 황다랭이는 높았다. 유목군 조업에서 혼획된 종은 모두 11종이었으며 그중 상어류가 전 투망 시에 어획되었고 yellowtail kingfish가 마리수로는 가장 많이 어획되었다. 황다랭이의 체장 조성을 비교하였을 때 소형 황다랭이는 주로 유목 주변에 분포하는 것으로 나타났다.

• 수산해양기술연구
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• 제50권4호
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• pp.556-566
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• 2014

Korean distant water tuna longline fishery commenced in 1966 in the Atlantic Ocean. Since then, it has become one of the most important fisheries of Korea. By early of 1970s, total amount of tuna caught in the Atlantic Ocean was the highest among other Korean distant water tuna fisheries, but has become minor since 1990s. The annual catch of tuna and tuna-like species by Korean tuna longline fishery in the Atlantic Ocean was about 1,900 mt in 2013. Bigeye tuna was the predominant species in species composition followed by yellowfin tuna, Albacore tuna, Blue shark and Swordfish. Korean distant water tuna longline fishery have mainly operated in the tropical area of the Atlantic Ocean ($20^{\circ}N{\sim}20^{\circ}S$, $20^{\circ}E{\sim}60^{\circ}W$), fishing ground was almost similar as in the previous years. The length frequency of major species (Bigeye tuna, Yellowfin tuna, Albacore tuna, Blue shark and Swordfish) were estimated. As the result of length (size) frequency data on main species caught by lonline fishery in the Atlantic Ocean, main length intervals of bigeye tuna caught in 2011, 2012 and 2013 were 120~125 cm, 160~165 cm and 130~135 cm, respectively. For yellowfin tuna, those were 125~130 cm, 150~155 cm, 145~150 cm and for albacore, 109 cm, 102 cm, 109 cm and 106 cm respectively. For swordfish caught in 2011, 2012 and 2013, main length intervals were 130~135 cm, 125~135 cm and 125~130 cm, respectively, and for blue shark, 195~200 cm in 2011 and 185~190 cm in 2012, 2013.

• 수산해양기술연구
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• 제32권1호
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• pp.24-32
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• 1996

This paper described on relation between the catches of tuna and the distribution of water temperature of eastern fishing ground of Tropical region in the Pacific Ocean. The data of catches and water temperature used in this paper were based log book which # 27 CHENG RONG(Gross tonnage : 399 ton) had been worked eastern fishing ground(Lat : 09$^{\circ}$N- 14$^{\circ}$S, Long : 115$^{\circ}$- 149$^{\circ}$W)from January to October, 1991. The obtained result are as follows : 1. On the relation between the catches and the geographical distribution, bigeye tuna was higher catches at Lat 4$^{\circ}$- 9$^{\circ}$N, Long 135$^{\circ}$- 139$^{\circ}$W area in the equatorial counter current region where surface water temperature was range of 27.5$^{\circ}C$ to 27.9$^{\circ}C$, yellowfin tuna was higher catches at Lat 4$^{\circ}$- 9$^{\circ}$S, Long 145$^{\circ}$- 149$^{\circ}$W in the south equatorial current region where surface water temperature was range of 28.$0^{\circ}C$ to 28.4$^{\circ}C$ and albacore tuna was higher catches at Lat 10$^{\circ}$- 14$^{\circ}$S, Long 120$^{\circ}$- 124$^{\circ}$W area in the south equatorial current region where surface temperature was range of 26.5$^{\circ}C$ to 26.9$^{\circ}C$ 2. On the relation between catches and distribution of vertical water temperature, bigeye tuna was higher catches at the water temperature of 1$0^{\circ}C$ to 12$^{\circ}C$ on depth layer between 300m and 360m, yellowfin tuna was higher catches at the water temperature of 15$^{\circ}C$ to 19$^{\circ}C$ on depth layer between 180m and 280m and albacore tuna was higher catches at the water temperature of 12$^{\circ}C$ to 14$^{\circ}C$ on depth layer between 280m and 310m. Above the result, it seemed that bigeye tuna distributed deeper layer than yellowfin and albacore tuna.