• 수산해양기술연구
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• 제45권2호
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• pp.96-105
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• 2009

For an effective management of fisheries resources, we need fisheries informations necessary for the establishment of reasonable fishing effort and TAC distribution. We carried out fishing research using trammel nets in the coastal sea of Susan-port(Yangyang, Gangwondo, Korea) and Hupo-port(Uljin, Gyeongbukdo, Korea) and analyzed fishing power variation of the fishing gear in terms of species composition, condition and so on for both sites. A total of 29 species were caught with most dominant species of Hippoglossoides dubius followed by Pseudopleuronectes herzensteini, Lophius litulon and Alcichthys elongatus in Susan. The total number of species caught in Hupo was 37 species with most dominant species of Todarodes pacifius followed by Lophius litulon, Hexagrammos agrammus and Pseudopleuronectes herzensteini. CPUE of Susan fishing area per trammel net was 12.74 fish and 2.00kg on average, while it was 6.80 fish and 2.27kg on average for Hupo. The fishing power index for both sites was 1, placing the two fishing grounds in a same level.

• 한국수산과학회지
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• 제47권6호
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• pp.945-959
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• 2014

This study was conducted to provide basic data for optimal fisheries management through the accurate understanding the catches, fishing level, species composition, distribution characteristics and fisheries status of trammel net in Gangwon Province. As the results of trammel net survey, Pisces were collected 77 species, 1,983.0 kg, Crustacea 9 species, 569.0 kg, Cephalopoda 5 species, 75.3 kg, Gastropoda 12 species, 16.5 kg in the coastal waters of Sokcho and Pisces 55 species, 3,681.5 kg, Crustacea 6 species, 2,229.8 kg, Gastropoda 10 species, 72.8 kg, Cephalopoda 4 species, 10.1 kg in the coastal waters of Donghae, respectively. The catches of important species with season and depths showed that the main target species is Pleuronectidae spp. at all depth and Aptocyclus ventricosus at <100 m in Sokcho, Liparis spp. and Dasycottus setiger at 200-500 m in Donghae, respectively. The mean total length (cm) of Gadus macrocephalus and Aptocyclus ventricosus didn't appear significant difference, but the mean total length of Pleuronectidae spp., Liparis spp. and D. setiger in Donghae is bigger than in Sokcho. From the cluster and MDS analysis based on Bray-Curtis similarity matrix of fourth root transformed, catches data of dominant species in the coastal waters of Sokcho and Donghae was divided into three different groups of the demersal organisms community in 12 survey of Donghae (Group A) and Jul., Oct.-Dec. survey of Sokcho (Group B) and Jan.-Jun. and Aug.-Sep. survey of Sokcho (Group C).

• 수산해양기술연구
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• 제52권2호
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• pp.130-140
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• 2016

This study analyzed annual catch trend during 45 years and monthly catch of the least 10 years (2005~2014) for chub mackerel caught in the Korean coastal waters. To determine fishing status of chub mackerel, fork length measurements were conducted at least twice every week for 100 individuals randomly selected at the Busan Cooperative Fish Market from January of 2012 to December of 2014; and biological characteristics and proximate composition (moisture, protein, fat, ash) were analyzed by length class (I~IV) on a monthly basis from January to December of 2014. Monthly catch trend showed low level below 5,000 mt from February to July, whereas high level above 15,000 mt from October to December. For the period between 2012 and 2014, annual average catch proportion of juvenile were relatively high at 68.1%, 53.1% and 53.2% from January to April, before spawning season, while those were low at 21.5%, 20.7% and 29.12% from June to November. As for the change in the proximate composition per 100 g of muscle, protein and ash did not change much by seasons and length class, whereas fat and moisture contents showed large fluctuations and complementary relationship between the two factors. Regardless of length class, monthly average fat content, containing Omega-3, showed the lowest at 7.18 g in April and highest at 19.27 g in December, which exhibited 2.6 times difference from one another. Regardless of fishing seasons, fat content by length class were 19.06 g for the class I and 6.43 g for the class IV, which showed three times difference. Fat contents of the class I were high at 26.97 g and 27.19 g in November and December, while low at 8.37 g and 9.99 g in April and May. Especially, fat contents from January to May were 5.0 g, which was the lowest. Therefore, it is expected that consumer could indirectly contribute fisheries management through their understanding and wise consumption based on fishing status and fluctuation of proximate composition.

• 수산해양기술연구
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• 제52권4호
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• pp.386-393
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• 2016

It is essential to provide good environment for juvenile fish to grow and spawn in order to keep reproduction mechanism of fisheries resources. However, harvesting juvenile fish deprives adult fish of the opportunity to reproduce, thereby changing self-regulating renewable resources into non-renewable ones and preventing sustainable harvesting as well as reducing fishers' income. We reviewed the catch status of Korea on juvenile mackerel and analyzed how reducing the catch ratio of juvenile mackerel may affect the spawning stock and Korean fishermen's revenue. In addition, we analyzed the problem of caching juvenile mackerel in Korean fisheries and current efforts to protect and reduce the catch ratio of juvenile mackerel in Korea. Furthermore, we suggested future efforts to protect juvenile mackerel. The result of the study showed that reducing the catch ratio of juvenile mackerel from 44.4% to 30.0% would increase fishers' revenue by 60.6 billion KRW. We suggest the changing of purse seine fishery's catching methods from night operation to day operation, relocation of fishing vessels to move to other fishing grounds when fishing vessels meet high density of juvenile mackerel, and consumers' clever choice of consuming adult mackerel in order to accelerate the move toward protecting juvenile mackerel in Korea.

• 수산해양기술연구
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• 제47권2호
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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.

• 수산해양기술연구
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• 제55권3호
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• pp.198-205
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• 2019

The small yellow croaker (Larimichthys polyactis) is one of the representative high-class fish species in Korea. The catch of small yellow croaker in adjacent water fisheries has been continuously decreasing from 59,226 tons in 2011 to 19,271 tons in 2016. The small yellow croaker is caught by gillnet, stow net and bottom trawl, among which about 55~65% is caught by gillnet. For the sustainable use of small yellow croaker, the fishing power of small yellow croaker drift gillnet is very important. Therefore, the change of fishing power index were analyzed to identify the development of the vessel and gear technology that may have improved the fishing efficiency of the small yellow croaker drift gillnet fishery from 1960s to 2010s. Gross tonnage and horse power per fishing vessel was increased annually. The mesh size was 75.0 mm in the 1960s, but reduced to 60.6 mm in the 1980s and to 51.0 mm in the 2000s. In the 1960s, it was hauled out by manpower. However, the net hauler were modernized and supply rate was also increased since 1970. Due to the mechanization of the net hauler, the number (length) of used net gradually increased from 1.5 km in the 1960s to 7.5 km in the mid-1980s and to 15 km in 2010. Colour fish finders and positioning system were introduced and utilized from the mid-1980s. Surveys on the supply and upgrading of fishing equipment utilized visiting research. Therefore, the relative fishing power index in the small yellow croaker drift gillnet fishery increased from 1.0 in 1980 to 0.8 in 1970, to 1.1 in 1990, to 1.6 in 2000 and to 1.9 in 2010. The results are expected to contribute to reasonable fisheries stock management of the small yellow croaker drift gillnet fishery.

• 한국수산과학회지
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• 제46권2호
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• pp.168-175
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• 2013

The feeding habits of the black-edged sculpin Gymnocanthus herzensteini were studied using 944 specimens collected from February 2011 to January 2012 in the coastal waters off Mukho, Gangwondo, Korea. The G. herzensteini ranged from 11.8 to 36.3 cm in total length (TL). The percentage of empty stomachs in G. herzensteini was 40.2%, and the main prey items were Pisces, Euphausiasea, and Macrura. The smallest size group (11.8-15.0 cm TL) consumed mainly Polychaeta and Amphipoda. The quantity of prey increased in proportion to sculpin size. The composition of prey items and feeding habits of G. herzensteini exhibited seasonal fluctuations, that is, the main prey items during spring were Euphausiasea, whereas those during other seasons were Pisces.

• 수산해양기술연구
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• 제42권4호
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• pp.195-202
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• 2006

To determine the relative efficiency and mesh selectivity of gill net for the Pacific saury, Cololabis saira, a series of fishing experiments was carried out in the Northwest Pacific Ocean from August 13 to October 13 in 2002, using gill nets of different mesh size(30, 33, 35, 37, 39 and 42mm) constructed from two kinds of twine material(monofilament, twisted multifilament nylon web). The relative efficiency of two material gears was expressed as the ratio obtained by dividing monofilament catch by multifilament catch in number. The master selection curve of each material gear was estimated by applying the extended Kitahara's method. The catch of experimental gears is mostly Pacific saury(98.6%), Cololabis saira. The kinds of bycatch are common squid(0.7%), Pacific mackerel(0.6%), etc. Catch comparisons in the two gears showed that monofilament nylon nets are 1.7 times more efficient. The optimum values in monofilament and multifilament gill net for Pacific saury are 8.28 and 8.23, respectively.

• 한국수산과학회지
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• 제56권4호
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• pp.419-427
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• 2023

This study, analyzed the stomach contents, stable isotope signatures (δ¹³C and δ¹⁵N) in muscle tissue, and potential food sources (particulate organic matter, Zostera marina, epiphytes, and zooplankton) of Sardinops melanostictus in the southern coast of Korea to evaluate its dietary changes across seasons (summer and autumn 2022). The diet of S. melanostictus predominantly comprised organic detritus (99%) regardless of the season. The isotope results showed that S. melanostictus had mean δ¹³C and δ¹⁵N values of -17.7±0.4‰ and 10.6±0.5‰, respectively and seasonal variations were observed (t-test, P=0.010, P=0.002). However, the isotopic mixing model showed that particulate organic matter was a major nutritional source for S. melanostictus in summer and autumn (88.7% and 90.2%, respectively). Based on the stomach contents and stable isotope signatures, these results may help improve the understanding of S. melanostictus and establish the management measures for their conservation.

• 한국수산과학회지
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• 제54권1호
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• pp.129-134
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• 2021

This study used the commercial fishing data of Korean high sea bottom longline vessels in the South West Atlantic Ocean from 2013 to 2019 to identify the distribution of fishing grounds of Korean longline vessels. We estimated the CPUE of the Patagonian toothfish Dissostichus eleginoides and the changes in its stock status. The fishing grounds of Korean longline vessels were observed to concentrate on the exclusive economic zone (EEZ) boundary between Argentina, Uruguay, and Falkland owing to the high seas of 41-55 °S in the south and 49-60 °W in the west. A high intensity of fishing was seen in the middle area, which was horizontal from the 3.1 subarea. In all the three subareas, CPUEs have had the tendency to decline since 2013. Although the CPUEs in the 3.2.1-2 subareas were the highest in each subarea, there was no significant difference in each subarea (P>0.05). It is believed that the establishment of a regional fisheries organization or the strengthening of the management of FAO is necessary for the management of Southwest Atlantic fisheries and sustainable fishing, because the portion and scope of Korean longline vessels are very low in the Southwest Atlantic; however, the CPUE is estimated to have declined.