• 수산경영론집
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• 제35권1호
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• pp.23-56
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• 2004

The offshore trawl fishery is seeking its survival way to overcome current management conditions in red, resulted from the bilateral agreement with China and Japan. However, this movement magnifies conflicts between fisheries on the contrary and it is thought to be impossible to get over current situations. For all that, this study is aimed at investigating how this current situations have occurred. The management freedom as response to the change in fishing conditions of a certain fishery, in case of Korea, is affected by institutional regulations. The example of this is controls on fishing gears, fishing vessels, and fishing grounds. The most exposure of this control is a segmentation of institutional fisheries. The initial segmentation of the offshore trawl fishery in Korea was occurred in the period of Japan's colonization when the degree of use of fishing grounds was limited geographically. At that time, fisheries were divided by fishing areas, but it did not divide the fishery itself. The large - sized fishing vessels were developed politically to be more competative to Japanese fishing vessels since 1950s. During this time, the trawl fishery was merged into current Eastern trawl fishery and South - Western trawl fishery. It was also inevitable to divide into the pair trawl and single trawl fishery as a result of the physical mergency between Western trawl and Southern trawl fishery. In order to develop the trawl fishery, new licenses were issued on the shrimp trawl fishery, through which it was expected to boost the trawl fishery. As opposed, the shrimp trawl fishery was changed into the mid - sized trawl fishery, targeting on the eastern fishing areas and the large - sized trawl fishery was developed since the late of 1970s with the development of filefish processing industry. The large trawl fishery that led in development of offshore trawl fishery since the late of 1950s was started to divide into a pair trawl and single trawl according to the fishing method and capital power. It finally became an institutionally independent fishery in 1980s, respectively. Looking into these historical process, the segmentation of the trawl fishery is thought as a result of the lack of long - term perspective and as a production of trial and error resulted by unprepared policy. As a result, these segmentation of fisheries roles as critical obstacles in harmonization of fisheries and in overcoming of current situations. Therefore, the review of this institutional segmentation of the offshore trawl fishery should be taken for an optimal redistribution of fishing grounds suits with business and fishing technology. For this, the fishery must be divided into large capitalized fishery and small - mid fishery with consideration of capital, fishing method, and the condition of use of fishing grounds. In addition to this, by limiting outline of fishing ground that the large fishery can harvest, it must allow for the small - mid fishery to catch with its own boundary. Furthermore, by launching buyback programs on the trawl, eastern trawl, pair trawl, it can provide broader fishing grounds where the fishery can harvest with management freedom.

• 한국수산과학회지
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• 제41권6호
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• pp.485-492
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• 2008

To propose proper vessel characteristics for sustainable fisheries in Korean waters, we analyzed the fishing capacity, scale efficiency and utilization of large pair-trawl vessels based on the database of catch, effort and vessel characteristics (gross tonnage and engine power) in 1990 by applying data envelopment analysis (DEA). The input factors were gross tonnage, horse power and days operated; whereas the output factor was expected catch by vessel characteristics. The optimal vessel types, selected based on the input-oriented technical efficiency and gross tonnages, was 100 GT with engine power <600 HP. The output-oriented unbiased estimate of capacity utilization (CD) decreased with increasing vessel tonnage. For the same tonnage vessels, the CD decreased with increasing engine power.

• 한국수산과학회지
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• 제46권6호
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• pp.917-922
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• 2013

Changes in fishing ground of the large pair trawler were investigated by year, month and species off Korean waters. We used catch data by sea-block lat.${\times}$long.:$30^{\prime}{\times}30$) of the National Fisheries Research and Development Institute (NFRDI) and monthly fishing production statistics of Korean statistic information service from 1990 to 2007. In the 1990s, the demersal fish like Larimichthys polyactis, Collichthys sp, Portunus trituberculatus and Muraenesox cinereus were the dominant species, and in the 2000s, they were changed from demersal fish into pelagic fish like Scomberomorus niphonius, Scomber japonicus, Engraulis japonicus and Todarodes pacificus. Species composition of catch showed temporal variation by cluster analysis deviding into 4 period, 1990-1994, 1995-2000, 2001-2003 and 2004-2007. Fishing ground in the 2000s was decreased up to 2/3 in the 1990s, while the density of catch in the fishing ground in 2000s was higher than the 1990s.

• 수산해양기술연구
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• 제39권1호
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• pp.33-43
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• 2003

본 연구는 현재 국내에서 사용되는 쌍끌이 중층망 어구어법에서 문제점으로 지적되고 있는 고속예망에서 망고의 제어가 어렵다는 점, 망목에 뜸이 걸려서 파망이 자주 일어나는 점, 네트드럼에 감기는 어구부피가 너무 크다는 점 등의 해결방법으로 무부자 쌍끌이 중층망의 모형실험을 통하여 우리 나라 쌍끌이 중층망에 대한 적용 가능성을 검토하는데 있다. 이를 위하여 850ps급 쌍끌이 기선저인망어선에서 현재 사용되는 실물망을 1/100로 축소 제작한 모형망에서 뜸을 모두 제거하고 끌줄을 양쪽으로 각각 두가닥으로 분리한 후 추를 부착하여 아래끌줄의 길이를 조절함으로써 망고를 제어할 수 있는 무부자 쌍끌이 중층망의 모형어구를 제작하여 회류수조에서 유속에 대한 아래끌줄의 길이에 따른 어구의 전개성능 등을 규명하고 기준형과 비교 분석한 결과를 요약하면 다음과 같다. 1. 유체저항은 무부자망이 기준형보다 약 10∼20%정도 작았으며, 무부자망의 유체저항은 동일유속에서 아래끌줄이 길어짐에 따라 약 1ton씩 증가하였다. 또, 동일유속에서 dL이 10m씩 증가함에 따라 아래끌줄에 작용하는 저항은 약 5%씩 감소하고, 그 반면에 윗 끌줄에 작용하는 저항이 증가하였다. 2. 망고는 직선에 가까운 지수함수적으로 감소하는 경향을 보였으며, 동일유속에서 아래끌줄이 길어짐에 따라 증가하여 로그함수적인 경향을 보였다. 또한, 망고감소율은 무부자망의 경우가 기준형보다 작게 나타났으며, 그 차이는 유속이 증가함에 따라 더욱 커져 dL이 30m인 무부자망을 기준으로 3.0knot일 때 12%, 4.0knot일 때 25%로 나타났다. 3. 망폭은 유속이 증가함에 따라 약 2m 내외로 거의 일정하였으며 무부자망이 기준형보다 크게 나타났다. 4. 망구면적은 유속이 증가함에 따라 지수함수적으로 감소하는 경향을 보였으며, 망구면적의 감소율은 기준형보다 무부자망이 더 작게 나타났다. 여과량은 유속이 증가함에 따라 로그함수적인 경향을 보였으며 기준형이 3.0knot 이상에서 급격히 감소하였지만, 무부자망은 4.0knot까지 증가하였다가 완만하게 감소하였다. 5. dL의 최대적정길이는 망구면적 및 여과량이 최대인 30m일 때이며, 추의 최적위치는 4개의 그물목줄이 연결되는 지점이었다.

• 한국수산과학회지
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• 제41권5호
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• pp.346-352
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• 2008

Yellow croaker (Larimichthys polyactis) is a major target species of large pair trawl fishery in the East China Sea. To standardize catch per unit effort (CPUE) of yellow croaker for the large pair trawl fishery, generalized linear model (GLM) was applied to evaluate and eliminate the influence of the explanatory factors (year, month, horse power and gross tonnage of vessel) on daily catches per boat collected and compiled by National Fisheries Research and Development Institute (NFRDI) from 1990 to 2007 at the fishery auction places of Busan, Masan and Incheon in Korea. Results of GLM showed that all of the factors significantly influenced on CPUE, explaining 36% of the total deviance. The standardized CPUE indicated that the abundance of yellow croaker in 2000's was 1.7 times higher than the CPUE in 1990's.

• 수산해양기술연구
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• 제51권2호
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• pp.203-211
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• 2015

The purpose of this study is to identify the flow resistance of the bottom pair trawl nets. The bottom pair trawl nets being used in fishing vessel (100G/T, 550ps) was selected as a full-scale net, and 1/10, 1/25 and 1/50 of the model nets were made. Converted into the full-scale net by Tauti's modeling rule and Kim's modeling rule, when resistance coefficient k of each net was calculated by substituting into above equation for flow resistance R and wall area of nets S values of each net ${\upsilon}$. Because resistant coefficient k decreases exponentially according as flow velocity ${\upsilon}$ increases to make $k=c{\upsilon}^{-m}$, c and m values of each net were compared. As a result, as the model was smaller, c and m values was smaller in the two rule into standard of 1/10 model value, decrease degree of 1/25 model was almost same in the two rule, decrease degree of 1/50 model was very big in Tauti's modeling rule. Therefore, in the result of experiment, because average of c and m values for similarly 1/10 and 1/25 model were given $c=4.9(kgf{\cdot}s^2/m^4)$ and m=0.45, R (kgf) of bottom pair trawl net could show $R=4.9S{\upsilon}^{1.55}$ using these values. As in the order of cod-end, wing and bag part for 1/25 and 1/50 model net were removed in turn, measured flow resistance of each, converted into the full-scale, total resistance of the net and the resistance of each part net were calculated. The resistance ratio of each part for total net was not same in 1/25 and 1/50 model each other, but average of two nets was perfectly same area ratio of each part as the wing, bag and cod-end part was 43%, 45% and 12%. However, the resistance of each part divided area of the part, calculated the resistance of per unit area, wing and bag part were not big difference each other, while the resistance of cod-end part was very large.

• 수산해양기술연구
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• 제57권2호
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• pp.93-106
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• 2021

Changes in the fishing grounds for four drag-bagnet fisheries (large trawl, large pair trawl, large Danish seine and middle Danish seine) were investigated by year and sea-blocks in Korean waters. We used catch and effort data by sea-block (latitude × longitude: 30' × 30') of the National Institute of Fisheries Science (NIFS) and yearly fishing production statistics of the Korean statistic information service from 2008 to 2014. The main benthic habitat of fishing ground was sand and sandy mud material. The average swept areas for the four fisheries were 181.7 km², 606.4 km², 2,720.9 km² and 252.8 km², respectively. The main fishing ground was around Jeju Island and the eastern South Sea. The main fishing ground moved to the northern part of the South Sea during the study period due to a closure of fishing grounds and changes in the target species.

• Ocean and Polar Research
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• 제39권1호
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• pp.61-71
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• 2017

This study estimates the cost function through offshore fishery cost data and analyzed the economies of scale of Korea's offshore fishery. For the estimation of the cost function, translog cost function was used, and the analysis implemented the panel analysis of the panel data. Also, annual economies of scale of the offshore fishery and economies of scale of 14 offshore fisheries in 2015 were analyzed using translog cost function coefficient estimation. The analysis result of economies of scale of Korea's offshore fishery showed that with the exception of 2003, economies of scale exist in all periods of time. However, as it almost reaches the minimum efficient scale, it was revealed that further scale expansion will bring inefficiency. Thus, according to the analysis result, Korea's offshore fishery requires a scale reduction policy rather than scale expansion policy, and this seems to coincide with the current government's fishery reconstruction policy and its practice such as the fishing vessel buyback program. The analysis result of economies of scale of each offshore fishery in 2015 showed that economies of scale of each offshore fishery exists with the exception of five trawl fisheries such as large pair-trawl and large otter trawl and large purse seines. This strongly suggests that the five fisheries and Large Purse Seines with non performing economies of scale need urgent scale reduction and should be the first target for the government's fishery reconstruction policy.

• 한국수산과학회지
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• 제56권6호
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• pp.916-922
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• 2023

An abnormal shape of Bathyraja brachyurops was first reported from the catch of a bottom trawl in the southwest Atlantic Ocean in June 2022. Both pectoral fins of the specimen did not fuse with the head, resulting in a horn-like structure separated from the sides of the eyes. Analysis of mitochondrial DNA cytochrome c oxidase subunit I sequences showed that our specimen was perfectly matched to Bathyraja brachyurops registered with the National Center for Biotechnology Information. Our specimen possessed the following morphological features: a pair of flexible but elongated and pointed horns on the head; rough dorsal disc, densely covered with numerous small denticles on the head, anterior margin of pectoral fins and median line of the disc; a thorn between the first and second dorsal fins; and a pair of large ocelli at the base of pectoral fins. Unlike the normal B. brachyurops, our specimen had a slender clasper and no nuchal thorns, which may be related to the morphological abnormality. The horn-like structure on the head may be owing to the lack of fusion between the pectoral fins and head during early embryonic development.

• 한국수산과학회지
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• 제49권3호
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• pp.376-384
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• 2016

Seasonal catch distributions of large purse seines and daily landings of coastal set nets were analyzed to understand the migration path of the Spanish mackerel Scomberomorus niphonius around Korean waters. The Spanish mackerel start to move toward the coastal region in the South and West Sea in May for spawning and stay until July, when spawning finishes. Afterwards, they start to migrate to the East China Sea and the southern East Sea and are found irrespective of the onshore and offshore regions. Therefore, they disappear from the offshore region during the spawning season in June and July, and a new recruitment population of age 0 begins to inflow into the coastal fishing grounds in the South Sea and West Sea in August, one month earlier than in the Japanese coastal region of the East Sea.