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MODEL EXPERIMENT OF STOW NET (안강망어구의 모형실험)

  • KO Kwan Soh;KIM Yong Hae
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.12 no.4
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    • pp.201-207
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    • 1979
  • The stow net now used in the Yellow Sea, are traditional bag net with the opening held by a lighter upper and a weighted lower beams standing against the current. Such bag net anchored at the bottom are known in many countries, particularly in the estuaries of large rivers, but more rarely in sea fisheries, because they are too much affected by the weather, moreover a permanent strong current is necessary. Some scientists intended to improve this fishing gear, using the shearing devices instead of a lighter upper and a weighted lower beams in order to widen mouth of the stow net however they are unsuccessful. One-fortieth scale model net of the stow net was tested in a circular water tank with an effective volume of $5.67m\times1.76m\times1.00m$ of observing the configuration and tension of the net. Experiments were carried out under the various combination including water velocity, spherical floats and elevating floats with the shearing hoods instead of the upper beam. We found those devices offered a very low resistance per net area to current compared with the spherical floats or upper beam, and had a fairly good shearing power at any velocity and direction of the current. The total resistance (R) of the model net to which shearing hoods and floats are attached can be induced by the following formula under the condition of 0.25m/sec to 0.5m/sec, $$R(kg)=3.11V^{1.54}$$ The height (h) of the improved model net (m-B) is higher than traditional model net(m-A) with upper and lower beams, m-A: h(cm)=89.22-2.42(V-15). $V\geqq15,\;cm/sec$ m-B: h(cm)=89.20-0.78V (V:cm/sec) The catch efficiency of improved model net is 1.5 times traditional model net.

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A Study on the Basic-Design of Inside-Sea Fishing Vessel by Economic Optimization Technique (경제성 최적화 기법에 의한 연근해 어선설계에 관한 연구)

  • 박제웅
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.3
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    • pp.287-295
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    • 1995
  • fishing boat is a specialized vessel which is intended to perform certain well defined tasks. Its size, deck-layout, carrying capacity and equipment are all related to its function in carrying out its planned operations. Therefore the process of fishing boat design is inherently combined with optimization of the design variables called the economic optimization criteria. Optimization then is a process in which minimum value of weight or cost is established through evaluation of consecutive designs in which one or more design parameters are varied. This paper is to study the basic-design of Stow-net fishing vessel in the Mok-Po region. The main task is developed the preliminary design model of engineering economic system in order to use optimization techniques from operation research the design problem needs to be expressed in terms of objective function and numerous constrains like : speed, fish hold capacity, fishing range, displacement and weight, ratio of main dimensions, etc. The objective function represents the criterion which is NPV such as the ratio of revene/cost. When using computers of limited capacity like P/C, the developed basic-design model of the economic optimization procedure must be simplified to V, Cb, L/B, Dv, Db and less than 15 constraint equations. The main conclusions of this study have attempted to show that economic considerations are essential in Stow-net fishing vessel basic design and operations, and that techno-economic evaluation is an important tool for the design of Stow-net fishing vessel in 69ton and 79ton.

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Catches of main species and bycatch according to the codend mesh sizes of stow net on anchor in the West Sea of Korea (서해안 안강망의 끝자루 망목크기에 따른 주요 어종의 어획과 혼획)

  • Cho, Sam-Kwang;Cha, Bong-Jin;Kim, Hyun-Young
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.2
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    • pp.88-98
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    • 2011
  • Experimental fishing was carried out to compare the catches of main species and bycatch according to the codend mesh size (raschel, 15mm, 25mm, 35mm, 45mm) of stow net on anchor in the coastal waters of Seocheon after manufacturing five kinds of fishing gears and commercial fishing boat (7.93 tons) was used for it. Anchovy (Engraulis japonicus), southern rough shrimp (Trachysalambria curvirostris), beka squid (Loligo beka), cuttle fish (Sepia esculenta), swimming crab (Portunus trituberculatus) were dominant on the five kinds of experimental fishing gears. Southern rough shrimp was caught from all kinds of fishing gears and catches of anchovy was highest in the raschel codend, southern rough shrimp for 15mm, 25mm, 35mm codend and beka squid for 45mm codend. Bycatch proportion against total catches was 623,376g (28.7%) for 2,171,844g in raschel, 11,932g (1.7%) for 704,451g in 15mm, 3,616g (1.6%) for 221,432g in 25mm, 9,276g (4.9%) for 191,052g in 35mm and 2,724g (5.3%) for 51,431g in 45mm.

Species Composition and Community Structure of Fish by Coastal Stow Net Catch from the Coastal Waters Off Boryeong, Korea (서해 보령 연안 연안개량안강망에 어획된 어류의 종조성 및 군집구조)

  • Choi, Dong hyuk;Yoon, Byoung il;Kim, Maeng jin;Lee, Seung jong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.53 no.5
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    • pp.761-772
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    • 2020
  • In order to study about species composition and community structure of fish in the coastal water off Boryeong were investigated from January 2018 to December 2019. A total of 10,863 individuals of 87 species of 44 families were collected. The dominant species were Liparis tanakai accounted for 19.8 percent of the total with Amblychaeturichthys hexanema and Collichthys niveatus accounted for 12.4 percent and 11.0 percent of the total number. A cluster analysis based on the Bray-Curtis similarity revealed that the fish community divided into two groups, According to season. The fish species that appeared summer and autumn were mainly migratory, while the fish species that appeared in spring and winter were mainly resident species. Fish caught by stow net had a high percentage of immature fish. It presented that coastal water off Boryeong is located an important spawning and nursery for fisheries resource.

Seasonal Fluctuations and Species Composition of Fish Collected by Long-bag Stow Net in Nang-island, Yeosu (여수 낭도 연안에서 낭장망에 어획된 어류의 종조성 및 계절변동)

  • Yu, Tae-Sik;Youn, Byoung-Il;Kim, Joon;Han, Kyeong-Ho
    • Korean Journal of Ichthyology
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    • v.32 no.2
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    • pp.91-96
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    • 2020
  • Seasonal fluctuation in abundance and species composition of fish in coastal waters off Nang island were investigated using seasonal samples collected by long-bag stow net in 2017. A total 10,208 fish were sampled and classified into 37 species, 26 families, and 9 orders. The dominant species were Engraulis japonicus (4,886 individuals, 47.9%), Pennahia argentata (842 individuals, 8.2%), and Ilisha elongata (369 individuals, 3.6%). The diversity index was the highest in May (H'=3.23) and the lowest in November (H'=1.24). The dominance index was the highest in November (D=78.7%) and the lowest in May (D=22.4%).

Classification of Fishing Gear (어구의 분류)

  • 김대안
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.32 no.1
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    • pp.33-41
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    • 1996
  • In order to obtain the most favourable classification system for fishing gears, the problems in the existing systems were investigated and a new system in which the fishing method was adopted as the criterion of classification and the kinds of fishing gears were obtained by exchanging the word method into gear in the fishing methods classified newly for eliminating the problems was established. The new system to which the actual gears are arranged is as follows ; (1)Harvesting gear \circled1Plucking gears : Clamp, Tong, Wrench, etc. \circled2Sweeping gears : Push net, Coral sweep net, etc. \circled3Dredging gears : Hand dredge net, Boat dredge net, etc. (2)Sticking gears \circled1Shot sticking gears : Spear, Sharp plummet, Harpoon, etc. \circled2Pulled sticking gears : Gaff, Comb, Rake, Hook harrow, Jerking hook, etc. \circled3Left sticking gears : Rip - hook set line. (3)Angling gears \circled1Jerky angling gears (a)Single - jerky angling gears : Hand line, Pole line, etc. (b)Multiple - jerky angling gears : squid hook. \circled2Idly angling gears (a)Set angling gears : Set long line. (b)Drifted angling gears : Drift long line, Drift vertical line, etc. \circled3Dragged angling gears : Troll line. (4)Shelter gears : Eel tube, Webfoot - octopus pot, Octopus pot, etc. (5)Attracting gears : Fishing basket. (6)Cutoff gears : Wall, Screen net, Window net, etc. (7)Guiding gears \circled1Horizontally guiding gears : Triangular set net, Elliptic set net, Rectangular set net, Fish weir, etc. \circled2Vertically guiding gears : Pound net. \circled3Deeply guiding gears : Funnel net. (8)Receiving gears \circled1Jumping - fish receiving gears : Fish - receiving scoop net, Fish - receiving raft, etc. \circled2Drifting - fish receiving gears (a)Set drifting - fish receiving gears : Bamboo screen, Pillar stow net, Long stow net, etc. (b)Movable drifting - fish receiving gears : Stow net. (9)Bagging gears \circled1Drag - bagging gears (a)Bottom - drag bagging gears : Bottom otter trawl, Bottom beam trawl, Bottom pair trawl, etc. (b)Midwater - drag gagging gears : Midwater otter trawl, Midwater pair trawl, etc. (c)Surface - drag gagging gears : Anchovy drag net. \circled2Seine - bagging gears (a)Beach - seine bagging gears : Skimming scoop net, Beach seine, etc. (b)Boat - seine bagging gears : Boat seine, Danish seine, etc. \circled3Drive - bagging gears : Drive - in dustpan net, Inner drive - in net, etc. (10)Surrounding gears \circled1Incomplete surrounding gears : Lampara net, Ring net, etc. \circled2Complete surrounding gears : Purse seine, Round haul net, etc. (11)Covering gears \circled1Drop - type covering gears : Wooden cover, Lantern net, etc. \circled2Spread - type covering gears : Cast net. (12)Lifting gears \circled1Wait - lifting gears : Scoop net, Scrape net, etc. \circled2Gatherable lifting gears : Saury lift net, Anchovy lift net, etc. (13)Adherent gears \circled1Gilling gears (a)Set gilling gears : Bottom gill net, Floating gill net. (b)Drifted gilling gears : Drift gill net. (c)Encircled gilling gears : Encircled gill net. (d)Seine - gilling gears : Seining gill net. (e)Dragged gilling gears : Dragged gill net. \circled2Tangling gears (a)Set tangling gears : Double trammel net, Triple trammel net, etc. (b)Encircled tangling gears : Encircled tangle net. (c)Dragged tangling gears : Dragged tangle net. \circled3Restrainting gears (a)Drifted restrainting gears : Pocket net(Gen - type net). (b)Dragged restrainting gears : Dragged pocket net. (14)Sucking gears : Fish pumps.

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A Fish Community Caught by a Stow Net in the Water off Hwaseong City, the West Sea, Korea (경기도 화성 연안 안강망 어장의 어류군집)

  • Cha, Byung-Yul;Im, Yang-Jae;Jo, Hyun-Su;Kwon, Dae-Hyeon
    • Korean Journal of Ichthyology
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    • v.25 no.2
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    • pp.119-134
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    • 2013
  • Species composition, abundance and seasonal variation of the fish community in the water off Hwaseong City, the West Sea, Korea were determined using monthly samples collected by a stow net from March 2011 to February 2012. A total of 71 species, 608,801 individuals and 795,503.3 g of fish were collected during the study. Dominant species were Engraulis japonicus accounting for 97.3% (592,926 individuals) in total number of individuals and 78.2% (622,815.8 g) in total biomass. The other major species were Pholis fangi, Chaeturichthys stigmatias, Konosirus punctatus, Hyporhamphus intermedius, Amblychaeturichthys hexanema, Liparis tanakai, Pleuronectes yokohamae and Okamejei kenojei. Fish collected were 59 species, 190,406 individuals and 241,113.4 g in the surface stow net and 61 species, 418,395 individuals and 554,389.9 g in the bottom stow net. Catch rate was low from March to May although the number of species was high. Catch rate significantly increased from June, but the number of species was relatively low.

Design of Unification of Power device of Stow-Net Fishing System -Unification of Power Device by Hydraulic Power- (안강망 어로 시스템 동력장치의 통합화 설계 -유압동력을 사용한 동력장치의 통합-)

  • 문덕홍
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.35 no.1
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    • pp.65-76
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    • 1999
  • Our status of off-shore stow-net fishery is in face with many difficult problems; the lack of fisherman by evading the 3-D occupation, the safety accident by unskilled crew and old type fishing system. In order to solve those problems, it is necessary to save the man power and ensure the safety of fishing work by the effective utilization of power and automatization of fishing gear system. This is consists of the side drum driven by main engine, the net hauler, the bow and stern capstan, jib crane etc. Therefore, we suggest the design on unification of power device of fishing gear system as follows; (1) fishing system by uni-hydraulic power and (2) fishing system by electric motor and electro-hydraulic power.

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Study on the Improvement of Stow Net Fishing Technique and the Enlargement of Fishing Ground to the Distant Waters - 1 . Model Experiment of the Net - (안강망어법의 개량과 어장의 원해로의 확대를 위한 연구 - 1 . 어구의 모형실험 -)

  • Lee, Byoung-Gee;Kim, Jin-Kun;Lee, Ju-Hee
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.24 no.2
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    • pp.55-64
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    • 1988
  • Stow nets have widely been used in the western sea of Korea from the olden age. The original structure of a stow net is a large square-sectional bag net made of 4 netting panels, and the front fringes of top and bottom panels are connected to the top and bottom beams respectively. Wire ropes, which is originated from the holding anchor are gradually forked and biforked, and finally 4 pieces of wire rope (biforked pendants) are jointed to each beam. Much convenience caused by long and heavy beams were problemed, then some studies have been carried out to improve the net since 1930's. The most effective improvement were achieved in 1980 by Mr. Han and his colleagues. The key point of improvement was that the beams were removed and the belt shaped shearing device made by canvas was attached to the side panels, the head rope and ground rope to the front fringe of top and bottom panel, and biforked pendants are joined to the shearing device. Even though this is the epoch-making improvement of a stow net, the further study should be required to find out more effective method. The authors carried out a model experiment on the stow net to determine the vertical and horizontal opening of a net mouth, and also examine the front, top and side-view configuration of the net. The model net was constructed depending on the Similarity Law of Fishing Gear in 1/10 and 1/20 scale and set against to the current at shallow and speedy flowing channel. The vertical and horizontal openings were determined by using scaled bamboo poles, and the configuration was observed by using specially prepared observation platform and underwater observation glass, and also photographed by using specially prepared underwater photographic equipment. The results obtained can be summarized as follows: 1. The opening height and width of the shearing device varied in accordance with the relative length of the biforked pendants. Considering the height and width of shearing device in 6 cases of the arrangement system of biforked pendants, the best result was obtained in the case that the 2nd, 3rd and 4th pendents from the bottom-most was 5%, 9% and 4% longer than that. 2. On the top-view configuration the excessive deformation of head rope and ground rope were observed. In the actual net, 54m long head rope and ground rope were attached to the front fringe of top and bottom panels so that the head rope may be lifted to make the net mouth open highly. But actually the head rope and the ground rope are streamed backward without any lift, and also the netting followed the ropes were deformed until the 2/5 in the whole length of the net. This deformation may be guessed to disturb the entrance of fish school into the net and also caused the net to get caught by obstacles in the sea bed and to be broken largely. 3. Hydrodynamic resistance R of the actual net may be deduced as R(kg)=29.2$\times$103 v1.65. It is also expressed as R(kg)=5.9$\times$d/l$\times$ab v1.65. depending on the formula deduced by Koyama to estimate the resistance of trawl nets, where d/l denote the ratio between diameter of netting twine and length of mesh leg in every part of side panel, a and b, the stretched circumference of the mouth and the stretched length of the net, respectively.

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