• 수산해양기술연구
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• 제46권3호
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• pp.214-222
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• 2010

The paper presents investigations on to which degree the sinking speed of longlines is influenced by type of bait, bait sinking orientations and anchor weights. The main aim of this study is to obtain further insight in the ocean current displacement phenomena in demersal longlining. The sinking speed is one of the main factors deciding the current displacement. In an ongoing project, sinking speed experiments with longlines with 6 kg and 10 kg anchor weights have been carried out in the Trondheim fjord. The longlines used in the first experiments were rigged without bait and hook. The results of these experiments with two different anchor weights have revealed only a slight difference in the sinking speed, except for the part near to the anchors, even though the sinking speed of longlines in general is supposed to be much influenced by the anchor weights. The reason for the obtained result is supposed to be that the experiments have been carried out at relative shallow waters. Further studies have included bait sinking experiments in the flume tank. The experiments showed that the drag coefficient of "fillet type (flat)" bait varied from 0.763 to 1.735, while it for "elliptic type" bait varied from 0.62 to 1.483. Other activities have included calculation of the sinking speed of longlines as a function of the established resistance coefficients of bait of various shape and size for commercial longlining. The calculated sinking speed of a longline with the fillet type bait was found to be 12.4 to 16.5% lower than for a longline without bait.

• 생명과학회지
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• 제16권6호
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• pp.1044-1051
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• 2006

The barren ground is an abnormal phenomenon of coastal ecosystem in which seaweeds, are destroyed and mostly replaced by the coralline algae containing the calcium carbonate components. To restore the seaweed forest, We have exerted an effort in the local areas, Samchuck, Korea, where barren phenomena are profound. Two methods of seaweed forest construction developed in the present study are underwater longline and seed transplantation for the brown seaweed Costaria costata, a fast growing edible seaweed. The sizes of C. costata attached on the underwater longline were $96.7{\pm}2.2mm$ of blade length and $83.6{\pm}7.7g$ of blade weight in April. Thereafter the sizes declined from May. Similar pattern was obtained from in the transplantation method with maxima of $90.4{\pm}15.8mm$ and $70.1{\pm}31.7g$ for blade length and weight, respectively in April. It appeared totality maturation from two methods in May. This maturation time is the same like that of wild C. costata.

• Fisheries and Aquatic Sciences
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• 제13권3호
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• pp.257-259
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• 2010

This is the first report of Snyderina yamanokami, from the subfamily Tetraroginae of the family Scorpaenidae, collected in Korea. The specimen (175.3 mm long) was caught in the coastal waters of Jeju Island on a commercial longline hook on 9 September 2009. This species is characterized by the following morphological traits: 9-11 dorsal fin rays, 5-6 anal fin rays, 13-15 pectoral fin rays, 5 ventral fin rays, pectoral fin tip reaching or extending past the origin of the anal fin, palatines toothless, and four dark spots on the middle of the body. We suggest a new Korean name, "Keun-mi-yeok-chi," for S. yamanokami.

• Fisheries and Aquatic Sciences
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• 제15권3호
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• pp.251-253
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• 2012

A single specimen of Thyrsitoides marleyi (818 mm in standard length), belonging to the family Gempylidae, was collected for the first time in Korea from the coastal waters off Busan, Korea using longline with hooks on 27 January 2012. This species is characterized by the following morphological traits: palate with three fangs, dark dorsal spine membrane, ending part of soft dorsal and anal fin rays finlet-like, and tip of the jaw with a cartilaginous process. We suggest a new Korean name "Gal-chi-ggo-chi" for T. marleyi.

• Ocean and Polar Research
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• 제41권1호
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• pp.19-34
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• 2019

The present study obtained universal mathematical models of all elements and characteristics regarding hook and line fishing systems. To describe the hook and line fishing systems on site we used three kinds of coordinate systems: the earth based coordinate system, natural coordinate system, and flow (velocity) coordinate system. Mathematical models presented in this article allow us to define the shape of the fishing gear, the tension of the rope at different points, hydrodynamic resistance, diameter of the hook's wire, immersion depth of the fishing hooks, distance from hooks to the ground and the required lifting force of the floats. These models allow for the performance of computer simulations regarding any kinds of hook and line gears in still water or water where flow occurs.

• 한국수산과학회지
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• 제10권1호
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• pp.37-47
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• 1977

대서양 황다랭이(Yellowfin tuna)어업에 대한 최근의 자료를 국제대서양 참치 보존위원회(ICCAT)로부터 수집하며, 자원생물학적으로 분석하여 얻은 결과를 요약하면 아래와 같다. 1. 대서양에서의 상업적인 황다랭이 어업은 1955년에 시작되었으며, 한국은 1964년 연승에 의해 입어하기 시작하였고, 1972년 부터는 채낚기 어선도 출어하여 참치 어업이 이원화되었으나 아직은 연승에 의해 주로 어획하고 있다. 2. 대서양의 황다랭이 전체 어획량추이로 보면 어업이 시작된 이래, 연승어업의 portion이 극히 높았으나, 1966년부터 표층어업이 앞질러 1975년의 경우에는 전체 114.0천MT 중 연승은 25.5천 MT로 $23\%$에 불과하다. 그러나 한국은 연승어획국중에서는 1위를 마크하고 있다. 1. 대서양에서 황다랭이를 어획하기 위해 투입되는 모든 어획노력량을 연승의 낚시수로 환산한 바, 1974년의 경우 약 476백만 hooks 이었는데, 이중 연승은 163백만 hooks로 $34\%$이었다. 4. 황다랭이 어획량을 어획미수로 환산한바, 1973년에 8.6백만미로 평균 10.9kg짜리가 어획되었다. 5. 최근에 들어 오면서, 표층어업에서는 주군이 2세어군에서 1세어군으로, 그리고 연승에서는 3세어군에서 2세어군으로 야년화되어 가는 현상이 뚜렷했다. 6. 최근의 황다랭이의 평균 총사망계수(Z)는 1.5로 계산되었는데, 자연사망 계수를 0.8로 간주할 때 어획사망계수(F)는 0.7로 나왔다. 7. 1973년의 가입시 체중 계산은 2.7kg으로 나왔는데, 이는 ICCAT의 황다랭이 규제체중인 3.2kg 보다 훨씬 작다. 우리나라의 입장에서 볼 때, 연승은 별문제가 없으나 채낚기 어업의 경우, 이들 규제체중 미달어체의 혼획을 낮추는 문제를 조사${\cdot}$연구할 필요가 있다. 8. 가입량크기(Recruitment strength)를 비교한 결과, 강한 년급군의 가입량은 약한 년급군의 가입량에 비해 3배나 컸으나, 이들이 번갈아 나타나므로서 어획량에 미치는 영향을 최소화시켰다고 생각된다. 9. 대서양 황다랭이와 최대특속적 어획량은 95-145천 MT로 계산되었다. 이는 현재의 어획수준에 해당하는 값으로, 현재 이상의 어획노력의 투입은 오히려 어획량을 감소시키거나, 혹은 희망적인 경우라 할지라도, 잉여의 노력량 투입공에 해당하는 만큼의 어획량 증가는 어렵다고 생각된다. 10. 오늘날까지의 우리나라의 입장은 원양어업의 신장을 위해 어떠한 형태로 든지의 국제적인 자원규제조치를 부정적인 측면에서 받아들여 왔음이 사실이다. 그러나 최근의 연안국의 전관수역의 확산 움직임과 우리가 현재 사용하는 채낚기 및 연승의 선망에 비한 어법의 열세 및 어획량 portion의 상대적 감소등을 감안할 때, 적어도 표층어업과 연승별 어획량 quota 제의 실현이 장기적인 안목에서는 우리에게 안정적인 조업을 할 수 있는 길이 될것이라 생각한다.

• 수산경영론집
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• 제40권1호
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• pp.153-172
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• 2009

Developing foreign fishing ground executed in various uncertainty such as fishing price, oil price, exchange rate. But traditional economic evaluation method, CVP(Cost-Volume-Profit) analysis doesn't consider uncertainty of foreign fishing ground. So we need new approach about economic evaluation that can take into account uncertainty. This study focus on the economic evaluation about experimental survey of tuna fishing grounds in the north pacific ocean by sensitive analysis and simulation. The results of the economic evaluation can be summarized as follows. First, when we take it for granted that the other uncertainty factors except for each fishing price, oil price, and exchange rate are constant. CVP gross sales has positive relation to the increasing rate of oil price, exchange rate(W/$) and negative relation to the increasing rate of fishing price and exchange rate(W/${\yen}$). Second, when we are supposing that fishing price, oil price, and exchange rate are followed. the probability of less than CVP gross sales is A ship(48.87%), B ship(49.64%), C ship(50.55%). Consequently, the economic evaluation by sensitive analysis and simulation is more useful tool than CVP(Cost-Volume-Profit) analysis under uncertainty.

• 한국수산과학회지
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• 제42권6호
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• pp.695-702
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• 2009

This study includes spatial variations in the catch of billfishes in the Pacific Ocean and examines factors affecting interannual changes in the catch. Main billfish species caught by Korean tuna longline fishery were blue marlin and swordfish. A main fishing ground of the species was the tropical Pacific Ocean, while additional fishing ground of billfishes tended to be formed in the Pacific coast of Mexico in the El Nino periods. Further, the catch of billfishes was significantly related to CPUE (tons/average of the used hooks/vessel) in the entire Pacific Ocean as an index of stock abundance and equatorial SOI (EQSOI) as an index of El Nino event. Annual changes in the catch of billfishes in the Pacific Ocean could be regulated mainly by variations of stock abundance. In addition, increase of the density of billfishes in the tropical Pacific and additional formation of fishing ground by El Nino event possibly contribute to increase of the catch of billfishes in the Pacific Ocean. On the other hand, linear regression model may be more adequate in the analysis of relationships between fisheries data and indices made from using some environmental factors.

• 수산해양기술연구
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• 제56권2호
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• pp.126-137
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• 2020

This study collected and analyzed the fishing process of existing fishing boat and newly built fishing boat by using the video observation methods to understand the improvement of fishing operation efficiency and safety according to the scale change of coastal composite fishing boat. The fishing operation efficiency was calculated by analyzing the frequency of movement, the movement distance and the moving time per basket used in the fishing process to derive the improvement of the newly built fishing boat compared to the existing fishing boat. It was confirmed that the mean frequency of movements decreased to 13.9%, the average moving time decreased to 21.8%, the mean movement distance increased to 20.5% and the movement through the top of gunwale did not occur. Movement of frequency, increased and time according to the fishing operation were directly affected by the width of side passages and the presence or absence of walking obstruction such as bulwark stay, hatch coaming and fishing gears on deck. The results of this study are expected to be used as basic data for redesigning into a safe and efficient coastal composite fishing boat in the future.

• 수산경영론집
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• 제35권1호
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• pp.1-22
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• 2004

Since the red grouper stock was initially declared to be overfished by the NMFS in September 2002, the Gulf of Mexico Fishery Management Council must prepare for the red grouper rebuilding plan considering the following alternative management policies: Total Allowable Catch(TAC), 5 - month season closure, 1800 - pound trip limit, and 50 - fathom longline boundary. The first concern the Council has is to evaluate the effects of recommended policies and the second is to analyze the impact of management policies on yellow edge grouper. This is because the fleets harvest red grouper also catch yellowedge grouper, the regulations on red grouper are likely to allow fishing effort to be distributed into yellowedge grouper. Therefore, this study is aimed at evaluating the biological and economic effects of management policies considering simultaneously the impact of red grouper regulations on yellow edge grouper by developing a combined red grouper and yellowedge grouper bioeconomic model. The overall results indicate that management policies for red grouper would adversely affect the yellowedge grouper stock if yellowedge grouper is not protected by its regulations. The TAC policy has the most serious impact on the yellowedge grouper stock, while the 1800 - pound trip limit policy minimizes the reduction in the yellowedge grouper stock. However, the target stock size of red grouper is achieved as well as the largest net present value of returns is gained in the TAC policy.