• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.329-338
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• 2007

Data collected by on-board observers and from experimental surveys during 2004-2006 were analyzed to figure out the status of shark bycatch in Korean tuna longline fishery. Results obtained from 10 surveys indicated that 14, 13 and 1 species of shark were incidentally caught in Korean tuna longline fishery operated in the Pacific, Indian and Atlantic (Mediterranean) Ocean, respectively, and that shark bycatch accounted for about 29-31% of the total catch. Sharks brought aboard were processed in 3 ways; out of 1,127 sharks observed, 575 sharks (51.0%) were discarded after finning, 299 sharks (26.5%) were stored frozen after finning for future use and 253 sharks (22.4%) were released into the sea immediately after caught. The fin to body weight ratio of sharks was estimated to be about 4.7% which is similar to the guideline of 5% established by the international fisheries organizations. The underestimate of shark bycatch in Korean tuna longline fishery was significant because it was general practice that fishermen on-board did not count the discarded shark as a catch.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.246-255
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• 2017

The species composition and variation in abundance of fishery resources near Oenarodo, Go-heung Peninsula, Korea, were investigated by gill net, trap net, and longline in May, July, and October 2015 and 2016. During the study period, the total catch included 14 species in the gill net, 11 species in the trap net, and 4 species in the longline. The dominant species were Portunus trituberculatus and Raja pulchrain the gill net, Charybdis japonicaand and Octopus vulgarisin in the trap net, and Muraenesox cinereusin in the longline. The Catch Per Unit Effort (CPUE) per individual and per weight in the gill net were similar in May and July of 2015 and 2016. In October 2015, the CPUE per individual was 2.1 ind./h and the CPUE per weight was 505 g/h higher than the results in 2016, but there was no significant difference in the total CPUE between 2015 and 2016. In the trap net, the CPUE per weight was similar in both 2015 and 2016, but the CPUE per individual was 2.7 ind./h higher in October 2015 than in October 2016 and the total CPUE was not significantly different from 2015 to 2016. The CPUE per individual and weight in the longline were significantly higher in July and October 2015 than in the same months of 2016, but the total CPUE in 2015 and 2016 did not show a significant difference.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.2
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• pp.105-120
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• 2019

The species composition and abundance variations of fishery resources in the adjacent marine ranching area, Tongyeong, Korea, were investigated by shrimp trawl, gill net, and longline during the period of July, September, and October in 2016. During the study period, the total catch were 8,522.9 kg with 34 species from the shrimp trawl, 32 species from the gill net, and nine species from the longline. The dominant species were different by gear, which were Hypodytes rubripinnis and Parapercis sexfasciata in the shrimp trawl, Platycephalus indicus and Raja kenojei in the gill net, and Conger myriaster and Scomber Japonicus in the longline. In terms of spatial distribution, Yongchodo showed the highest total catch in number as well as of in weight while Jukdo showed the lowest total catch in number and Bijindo showed the lowest total catch in weight. The amount of demersal fish resources in the survey area estimated as 301 ha, was 99,396 individuals which was converted to be 8,552.9 kg. The amount of demersal fish resources by gear were of trawling area, which area is 127 ha, were 76,251 and 3,489.5 kg, 74 ha in the gill net and longline survey area was 16,213 and 3,457.3 kg, and the other 100 ha area was 6,932 and 1,606.1 kg. In this study, the minimum resources for demersal fish is 61,687 and 4,265.2 kg, and the maximum is 149,439 and 14,197.9 kg.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.292-298
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• 1994

Catching performance of a mechanized pollock longline system compared with traditional one were examined in order to evaluate the practicality during two cruises in the Sokcho area. Mechanized longline system consists of random baiter, bait cutting machine, storage rails, and line hauler. Baiting efficiency of random baiter was 90-95% with 4-5kt shooting speed. Catching performance of the first experiment, salted sand lance only used as a bait. shows no significant difference between mechanized operation with use fresh sand lance as a bait caught significantly more pollock than traditional one with use salted sand lance (P<0.016). Improved catch rates were about 2 times. As soak time goes on, relative catching efficiency shows a steady increase up to 6~7 hours and thereafter gradually decrease.

• Journal of Ocean Engineering and Technology
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• v.10 no.1
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• pp.92-99
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• 1996

Longline type aquaculture facilities are being used for scallpop culture in 30 m of water 2.5 km off the coast of Joomoonjin, Kangwon-do. In this paper, the facilities are modeled by the cabele-buoy-weight system, subject to the nonlinear behaviors of the mooring lines and the effects of current. Its static configuration is shown as a solution of 3-D nonlinear static equation and Runge-Kutta $4^{th}$ method is employed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.173-182
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• 2011

The purpose of this paper is to provide useful information for fishermen in the manner of investigation a sinking speed of current type tuna longline gear at the North Pacific Ocean as a new developed tuna longline fishing ground. The sinking depth of mainline in connection with different basket was investigated. The experiments were also performed with different materials such as Supermansen (i.e., PE) and Hitech (i.e., PA) for the mainline to investigate the sinking depth of mainline and hooks. Furthermore, the relation between the sinking depth of hooks and catches are investigated also. The sinking depth of mainline at the first and the last shooting basket shows deeper than that of middle part of a basket due to reduced shortening ratio. The sinking depth of mainline and hook with Hitech material shows more shallow than that of Supermanse material, even the Hitech case was designed to sink deeper than that of Supermanse case. The highest catches arise at the middle part basket as the hook number 7 with around 248m sinking depth. From the results, longline with Hitech material is needed to increase the sinking force for reaching the relevant sinking depth. Moreover, the current strength at the North Pacific Ocean will be considered for further commercial fishing.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.106-113
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• 1987

The Alaska pollack longline operations, which consist of baiting, shooting, hauling and arrangement of hooks, are dependant on manual labour up to the present. The automation against this traditional way is necessary to eliminate the manual operations and to reduce crew. We have developed a prototype longline system suitable for Alaska pollack longline gear, which is composed of an automatic baiting machine, an automatic line hauler, a hook cleaner and storage rails. The automatic bailing machine driven by hydraulic power is precise baiting method controlled sequentially, and the automatic line hauler is to haul up the mainline by means of hydraulic power and at the same time to split every hook and to carry it onto storage rail automatically. A series functioning tests on shooting and hauling apparatus were carried out in the laboratory and at sea. The results obtained are as follows ; 1. As for the baiting machine, the exciting time of solenoid which operates a directional valve, bait feeding and cutting time, is shortened according to the increase of pressure, and also, after cutting the bait, the over-rotated angle of the blade increased in accordance with the increase of pressure. 2. The baiting efficiency is about $90\%$ when using sand lance (Hypoptychus dybowskii), and the most proper pressure of the hydraulic circuit in feeding and cutting the bait is between $13\;kgf/cm^2\;and\;20\;kgf/cm^2$. 3. The hook splitting rate of the automatic line hauler is about $95.5\%$ regardless of hauling speed and materials of snood. 4. The case of unseparating hook is appeared when the snood gets entangled or the hook is sticked in the mainline.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1994.06c
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• pp.31.3-32
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• 1994