• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.95-100
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• 2005

In order to improve the gill nets for croaker, Miichthys miiuy which is proper to the fishermen's income ans fisheries resource management, we had studied to the net height of present gill nets (mesh size 160mm, 50 mesh in depth), experimental gill nets-I(mesh size 150mm, 68 mesh in depth) and experimental gill nets-II(mesh size 142mm, 75 mesh in depth) in wter using the gill nets design ans analysis simulation system, and then investigated and analyzed the catch efficiency of each gill nets through the field fishing experiments. The net height of emperimental gill nets-I and experimental gill nets-II in water were estimated respectively about 1.5 times and 1.3 times higher than present gill nets which the net height is about 3.5m as the results of simulation considering the current of fishing fields. Total number of croakers which were caught by the persent gill nets was 62(body length 300~1,200mm), total catch weight was 398.7kg (mean 0.6kg/sheet). Total number of croakers which were caught by the experimental gill nets- I was 68(body length 600~1,100mm), total catch weight was 391.6kg (mean 1.2kg/sheet). Total number of croakers which were caught by the experimental gill nets-II was 28(body length 400~900mm), total catch weight was 99.2kg (mean 0.3kg/sheet).

• Environmental and Resource Economics Review
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• v.12 no.4
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• pp.663-686
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• 2003

This study is aimed at analyzing the effectiveness of TAC policy using a bioeconomic model. A surplus-production model is used as a population dynamic model, from which the yellowedge grouper is estimated to be overfished. As a result, a 10-year rebuilding plan using the TAC policy is established. According to the result of model, under the well-enforced system, the target stock biomass is achieved during the rebuilding period. Especially, in order to accomplish the target stock biomass, the annual quota should be allocated much less than 342 tons that NMFS recommended. The NPV over a 25-year under the TAC policy Is predicted to be less than under the status quo. The economic gains under the variable-catch TAC policy is less than under the constant-catch TAC policy as the interest rate decreases, while the NPV under the constant-catch is greater than under the variable-catch TAC policy when the interest rate is high.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.191-199
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• 2009

Fisheries resources collected by set net in the Mizo fishing ground off Namhae Island were studied from March to December 2004 to determine species composition and catch variation. The water temperature of the fishing ground ranged $10.9{\sim}25.1^{\circ}C$ A total of 69,147.5 kg comprising 39 species was caught during the survey period. Most of the catch was fishes (33 species); others included cephalopods (5 species) and crustaceans (1 species). The dominant species were migratory, such as Trichiurus lepturus, Ammodytes personatus, Engraulis japonicus, and Scomberomorus niphonius, and accounted for 81.2% of the total catch. Sub-dominant species were Sardinops melanostictus, Acanthopagrus schlegeli, shrimps, and Todarodes pacificus, but they accounted for only 12.1% of the total. The catch by set net during the fishing period was much higher in spring and in autumn than in summer, relating to the recruitment of dominant species. Although the number of species had a tendency to decreased after summer, the catch in autumn was also higher than that in spring due to high temperatures (>$17^{\circ}C$ and seasonal variation of dominant species. The dominant species in spring were A. personatus and E. japonicus and in autumn were T. lepturus, S. niphonius, and E. japonicus.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.171-178
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• 2015

Selectivity and by-catch are the main features used to define fish catch for fisheries management or to determine fishing gear efficiency. A fish girth distribution analysis was carried out to determine the retention rate of juveniles discarded and to establish common selectivity for a multispecies catch. Total body length, body weight, and girth of juvenile fish retained in the cod-end and cover net separately were collected using an 18-mm mesh cover net during 12 fishing trials with a 41-mm cod-end beam trawl. The by-catch weight ratio in the cod-end was twice that of the by-catch ratio in number. The 50% selectivity of body length and 50% girth of redfin velvet fish were not significantly different between the cod-end and cover net, whereas those of other fish species were significantly different between the cod-end and cover net. The difference in 50% selectivity girth of other fish between the cod-end and cover net was similar between cod-end mesh size and cover net mesh size. Furthermore, the difference in 50% body length selectivity of other fish between the cod-end and cover net was almost double the difference in girth. Girth selectivity in a multispecies catch using towed fishing gear was effectively used to determine fish and net mesh size.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.251-256
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• 2001

Catch characteristics according to the tide and fishing time were analyzed through the fishing log data of trawls which work at Arafura Sea of Indonesia. This study aimed to provide basic data to make a fishing plan from the catch difference according to fishing time after analyzing the suitable fishing time of fish species. The results obtained are summarized as follows ; 1. Catches were the largest at the day of very weak tide as 22.8% of total catch and was the smallest at the day of a little strong tide as 16.9% of total catch. 2 Catches of croaker Argyrosomus sp. ＆ Johnius vogleri, silver hairtail Trichiurus lepturs and coachwhip ray Himantura sp. were the largest at the day of weak tide(20.8%), very weak tide(33.8%), a little strong tide(22.0%) and catch for croaker and silver hairtail were the smallest at the day of a little strong tide(18.7%-10.0%) and coachwhip ray was the smallest at the day of strong tide(16.8%). 3. Catches were the largest at the time of 08:00-12:00 as 19.7% of the total catch and were the smallest at the time of 20:00-24:00 as 14.1% of total catch. 4. Catches of croaker, silver hairtail and coachwhip ray were the largest at the time of 00:00- 04:00(21.0%), 08:00-12:00(35.0%) and 12:00-16:00 (21.2%) and were the smallest at the time of 12:00-16:00(12.7%), 20:00- 24:00(4.6%) and 20:00-24:00(13.4%).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.3
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• pp.407-415
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• 2014

Fish was caught by a set net in Gwideok, Jeju island that was studied to determine monthly variation of species composition and catch from May 2005 to October 2006. Total catch was 54 species, 44,118 individuals, and 2,152,423.7 g during survey period. Dominant species were Trachurus japonicus and Siganus fuscescens that held 91.3% of total individuals and 71.3% of total abundance. The highest individuals and abundance of catch were in July 2005, and the lowest individuals and abundance of catch were in October 2006 and in October 2005, respectively. As the result, temporal change in abundance have corresponded with changing water temperature.

• ETRI Journal
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• v.45 no.2
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• pp.267-276
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• 2023

R&D strategies of companies with low and high technological levels are discussed based on the concept of technology convergence and divergence. However, empirically detecting enterprise technology convergence in the distribution of enterprise technology (total productivity increase) over time and identifying key change factors are challenging. This study used a novel statistical indicator that captures the internal technology distribution change with a single number to clearly measure the technology distribution peak as a change in critical bandwidth for enterprise technology convergence and presented it as evidence of each technology convergence or divergence. Furthermore, this study applied the quantitative technology convergence identification method. Technology convergence appeared from the separation of total corporate productivity distribution of 69 IT companies in Korea in 2019-2020 rather than in 2015-2016. Results indicated that when the total technological level was separated from the technology leading and technology catch-up, IT companies were found to be pursuing R&D strategies for technology catch-up.

• 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.

• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.210-219
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• 2001

The fisheries resources of the set net fishery on four fishing grounds (Pyuong Dae, Gu Eum, Du Moah, Gang Jeong) in coastal waters of Jeju Island were studied to the determine catch-variation characteristics from January, 1998 to December, 1999. A total catch of 153,862 kg was made through the survey period. The large total was related mainly to the high catch of Trachurus japonicus, which comprised 58.2% of the total. Other dominant species which account for 23.0% of the total catch were Siganus fuscescens, Todarodes pacificus, Loligo chinesis, Seriola lalandi, Sepioteuthis lessoniana, and Seriola quinqueradiata. Catch density was high in Gu Eum (more than 100,000 kg), whereas those in Pyuong Dae, Du Moah, and Gang Jeong were less than 30,000 kg in total. The fishing period of the set net fishery was from April to December, which was also closely related to the variation of the sea water temperature in the fishing grounds. The ranges of water temperature in the four fishing grounds were $18{\sim}26^{\circ}C$ in Pyuong Dae, $16{\sim}26^{\circ}C$ in Du Moah, $15{\sim}26^{\circ}C$ in Gu Eum, and $15{\sim}26^{\circ}C$ in Gang Jeong.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.520-529
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• 2014

Experiment was set up to analyze bycatch and discards situation including snow crap Chionoecetes opilio of whelk trap. Four types of trap were used: drum type trap with PE net; drum type trap with PBS net; cylinder type trap with PE net; and cylinder type net with PBS net. Three funnels were attached in drum type trap and two funnels were used in cylinder type trap. A fleet of traps was consisted with one hundred traps. 25 traps of each type were set on a line in repeated sequence. Field experiments were conducted with 6 fishing operations in the Uljin waters, East Sea in July 2014. Catch of target whelks were 173,261 g and catch rate was 48.7% of total catch, while bycatch were 182,571 g, 51.3% of tatal catch. The catch rate of bycatch was 2.6% higher than that of target catch. Bycatch weight of snow crap was the highest as 142,987 g and formed about 40.2% of total catch, followed giant octopus, Enteroctopus dofleini, 31,762 g (8.9%). Bycatch rate of cylinder type trap was 2.3 times higher than that of drum type trap. Discard rate (discard/(discard+landing)) was 43.6%. Discard rate was the highest at cylinder type trap with PBS net as 63.1%, followed cylinder type trap with PE net as 47.9%, drum type trap with PE net as 33.4%, the lowest at drum type trap with PBS net as 22.1%.