Choong-Sik Jang

An analysis on catch of the shrimp beam trawl fishery in Korea coastal sea

Experimental fishing operation by the shrimp beam trawl was carried out to investigate the bycatch in order to develop the selective fishing gear of the shrimp beam trawl fishery. The experimental trawling was performed by the prototype fishing gear in coast sea of Boryeong, Buan, Kangjin, Tongyeong and Geoje from 30 April to 13 November 2005. Bycatches of the experimental trawling were analyzed species composition, total length composition. The results obtained can be summarized as follows; Target fishes caught by the shrimp beam trawl were Palaemon gravieri, Crangon Hakodatei, Trachysalambria curvirostris, Parapenaeopsis tenellus, Rhynchocinetes uritai and Matapenaeus joyneri. And their fishing rate and total length range were 50.0%, 46.0%, 2.6%, 0.4%, 0.3%, 0.3% and 40-80mm, 40-80mm, 120-150mm, 60-80mm, 60-80mm, 60-120mm respectively. Bycatches caught by the shrimp beam trawl consisted of fishes of 30 kinds, 6 kinds of mollusk, 5 kinds of shellfishes and 3 kinds of crabs. The main fish was Engraulis japonicus, Platycephalus indicus, Paralichthys olivaceus, Leiognathus nuchalis and Conger myriaster, their occupied rate were 47.0%, 16.6%, 13.6%, 5.5%, 2.7% respectively, and their total length range were 60-150mm, 80-410mm, 80-600mm, 30-80mm and 150-460mm respectively. A number bycatch rates of shrimp beam trawl fishery were 99.7% in Buan, 60.0% in Kangjin, 14.6% in Boryeong, 10.6% in Tongyeong and 2.7% in Geoje, The weight bycatch rate were 99.9% in Buan, 75.1% in Kangjin, 57.1% in Tongyeong, 47.4% in Boryeong and 15.4% in Geoje.

Estimating the biomass of anchovy species off the coast of Tongyeong and Yeosu in South Korea in the spring and winter of 2013 and 2014

Anchovy (Engraulis japonicus) is one of the most important species in the South Sea of South Korea. In order to estimate the biomass of anchovy, acoustic surveys, concurrently with trawling, were conducted in April, July, and September of 2013 and February of 2014 off the coast of Tongyeong and Yeosu. However, anchovies were found only during spring (April) and winter (February) surveys. To display only anchovy species confirmed by trawls on empty spaced echograms, virtual echograms were created. Three target strength (TS) values of anchovy were used: TS_z

Opening efficiency and selectivity of Double-level type and Grid type in the shrimp beam trawl net

서 론 연안의 일정한 구획에서 새우만을 어획하도록 되어 있는 조망어업은 Jang et al., (2009)에서와 같이 새우와 어류들이 많이 어획되고 있으므로 새우만을 어획할 수 있는 선택적 어구를 개발하여 하루빨리 보급할 필요가 있다. 일반적으로 예망어법에 속하는 어업들의 부수어획률 이 다른 어법들에 비하여 월등히 높은데 그 중에서도 우 리나라에서 사용하고 있는 새우 조망어구는 유럽식 빔 트롤로 끝자루의 그물코가 매우 작기 때문에 부수어획 률이 어느 어업보다도 높은 실정이다. 그러므로 세계 각국에서는 부수어획률을 낮추기 위 하여 여러 가지 방안들을 채택하고 있는데, 현재 새우만 을 선택적으로 어획하기 위하여 사용하고 있는 어구로 는 자루그물을 상하로 분리하여 새우는 아래쪽 자루에 서 어획되도록 하는 새우의 서식수층을 활용하는 것과 상하식과 그리드식 새우조망 어구의 전개성능과 선택성

Species composition of the demersal fish assemblage in the coastal waters off Geomun island, Korea

The study aims at analyzing a species composition of the fish live in bottom of the coastal waters off Sejon island, Korea. To reach the goal of the study, a species composition and its seasonally fluctuation, a seasonally fluctuation of the dominant species and its appearance type were analyzed with the fishes caught by the bottom trawl in the coastal waters off Sejon island from May, 2011 to March, 2012. The results obtained can be summarized as follows; Fish caught in this area composes 10 orders, 25 families, and 37 species. The most dominant species in an number of fish was Pennahia argentata which was occupied at 42.1% from the whole number, the second most dominant species was Konosirus punctatus which was occupied at 14.2%. The most dominant species in a biomass of fish was Pennahia argentata which was 31.3% out of the whole catch, the next dominant species was Lophius litulonwhich which was 18.2%. The first group (Trichiurus lepturus, Zeus faber, Pennahia argentata, Chelidonichthys spinosus and Lophius litulon) was appeared at May, August, October, the second group (Sphyraena pinguis) was appeared at May and November, the third group (Pampus argenteus) was appeared at August, the fourth group (Pampus echinogaster, Leiognathus nuchalis, Konosirus punctatus and Engraulis japonicus) was appeared at March.

A study on the turning ability of a DWT 8,000-ton oil/chemical tanker by real sea trials - A comparison between the semi-balanced rudder and the flap rudder -

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test in ballast condition and full load condition, semi balanced rudder and flap rudder. The turning circle maneuvering were performed on the starboard and port sides with rudder angle at the normal continuous rating. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.

Feeding habits of white croaker, Pennahia argentata in the coastal waters off Sejon island, Korea

Eun-Hye KOH, Young-Su AN, Gun-Wook BAECK and Choong-Sik JANG* Department of Marine Production System / Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Cheondaegukchi-Gil 38, Tongyeong 650-160, Korea 1Department of Marine Biology & Aquaculture / Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Cheondaegukchi-Gil 38, Tongyeong 650-160, Korea

A study on the maneuverabilities of the marine research vessel CHARMBADA

This study was intended to determine the maneuverability of the vessel CHARMBADA. When the rudderangle was at 10, 20 and 30 , the maximum advance by slow, half and full ahead were varied in the rangeof 523.6 131.3m, 528.8177.2m and 530.6219.7m, respectively. The maximum transfer was 799.9181.3m, 792.1232.8m and 807.7316.9m, respectively. The turning circle ability was better duringstarboard turning. When the rudder angle was 10, 20 and 30, variation in the maximum advances was392.0m, 245.0m and 153.0m. The maximum transfer was 528.0m, 339.0m and 218.0m, respectively basedon the regression equations. As the rudder angle became bigger, the maximum advance or maximum transferbecame smaller by the exponential function. The advance inertia took 127sec, 145sec, 181sec each until thevessel speed was 7.0konts, 12.0konts, 17.0konts. The static inertia took 245sec, 269sec, 300sec each untilthe vessel speed was under 2.0konts and the advance distance was 114.4m, 181.2m, 197.0m each.Accordingly, the static inertia was inclined to increase to scale according to the increase in vessel speed. Forthe CHARMBADA, the smaller the rudder angle was, the much bigger the turning circle became due toadhesion to the skeg, thereby lowering the vessel s turning ability.Key words: Rudder angle, Maximum advance, Maximum transfer, Turning circle

The Opening Efficiency of Labor Saving net for the Anchovy Boat Seine

This study was conducted in order to improvement of fishing gear and fishing operating system for anchovy boat seine by labor saving improved nets. Field experiments were carried out observe geometry of nets and fishing operating system by catcher boats. The obtained results are summarized as follows : The Vertical net opening of fore wing net, wing net, inside wing net, square, fore bag net, flapper, after bag net of the labor saving improved net according to the distance between catcher boats were varied in the range of 5.07.8, 14.421.1, 16.221.2, 14.017.3, 11.713.9, 5.46.9, 8.29.8m respectively, varied in the range of 5078, 2536, 2431, 3138, 6173, 7191, 87104% of the actual ratio of net opening in each part. Labor saving improved net was performed instant net opening in fore wing net and maintained stable net opening and towing depth by means of attached net pendant. Also, it was minimized as net pocket phenomenon leading to guide anchovy for more catch by means of attached body net. The opening in accordance with distance between catcher boats and towing speed. The catch of labor saving improved net was increased than traditional net due to decrement of net resistance by improvement of bag net leading to increasement of towing speed and reduction of escape anchovy as well as improve nets of whole operation system.

Development of the Automatic Hauling Operation System by Three boats for Anchovy Boat Seine

This study was conducted in order to improve the automatic fishing operation system for anchovy boat seine by comparison with the fishing gear geometry and efficiency using the labor saving nets and the combined type net with midwater trawl. Field experiments were carried out to observe the geometry of nets and improve the fishing operation system by catcher boats. The vertical net opening of fore wing net, square, fore bag net and after bag net of the combined type net were varied in the range of 9.9~12.9. 16.2~28.2, 6.8~12.1 and 9.5~15.2m respectively, when the towing speed was 1.0m/sec and the distance between boats were 100m, 200m, 300m. The vertical net opening of the combined type nets was gradually decreased as function of with increasing the distance between catcher boats. Labor saving net which was maintained the net opening and towing depth stable was more suitable for the automatic hauling operation system by improvement of bag net rather than the combined type nets which was impossible in swallow depth and near to anchovy school. 3 boats hauling operation system of the labor saving net was carried out by crane with power block in 2 catcher boats for improvement of hauling operation and pushing equipment of anchovy cooking system in the processing boat for maintain more anchovy in dry frame. From the results of field experiments, 3 boats hauling operation system with power block and improved cooking system was very 3 boats hauling operation system with power block and improved cooking system was very useful and more practical as hauling time 20~35min and No. of fishermen 12~13 in comparison with the traditional system such as hauling time 30~50 min and No. of fishmen 28~38.

Underwater Geometry of the Anchovy Boat Seine in Process of the Fishing Operation

This study was carried out to observe the underwater geometry of the anchovy boat seine by two fishing operation systems. One was a traditional operation system that used a fish detecting boat, another was a new operation system that used the same fishing gear with floats and sinkers in comparison with a fish detecting boat. Vertical opening of the fishing gear that used a casting net, working depth of each part of the fishing gear that used a new operation system was almost canstant, but was gradually shallow in a traditional operation system. Just before hauling net, working depth of each part of the fishing gear that used a new operation system was maintained stable, but was vertically unstable in a traditional operation system because as rear part of the fishing gear was risen up the upper layer. Just after hauling net, working depth of the fishing gear that used a new operation system was also maintained stable, and then anchovy school could be lead to bag net.