• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.11-16
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• 1972

During the period from 1966 to 1968, total catches of Spanish mackerel averaged 6,000 to 7,000M/T per annual in Korea, and approximately 70 per cent of this amount was captured by drift nets. In an effort to improve the efficiency of drift nets, some experiments were conducted in 1969 to investigate the selectivity of material and mesh sizes. Seven different mesh sizes (80,85,95,100,105,110 and 115 mm) of both multi- and mono-filament netting were used, and the following results were obtained : 1, The body weight of Spanish mackerel taken with the seven different mesh sizes ranges from 0.5kg to 2.9kg, and the mode of body weight consists of three groups, 1kg ($21%$), 1.3kg($15\%$) and 1.5kg($19\%$). 2. For multi-filament net, 80 to 105mm mesh sizes were suitable to catch those three groups, and a little smalter than these for mono-filament net. 3. For Spanish mackerel only, the mono-filament material proved to have 1.5 times better selectivity than multi-filament : however, the latter proved superior for miscellaneous fish species due to its different size and shape. 4. Multi-filament net showed better selectivity for smaller species than mono-filament. (and mono-filament in general indicated opposite phenomenon.)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.341-351
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• 2013

Physical characteristics of PA (Polyamide) gill net and biodegradable gill net made by PBS (Polybutylene succinate) (mesh size 63mm, mesh thickness number 2, 2.5, 3) were analyzed to investigate catching efficiency of the biodegradable gill net for Pacific herring. Total 11 numbers of catching efficiency tests were carried out using commercial fishing vessel at Imwon port in Kangwon province from May to June 2013. The amount of catches were 1,535.7kg (18 species) through the catching efficiency tests and it is expected that the practicalization of biodegradable gillnet is possible because there is no difference for catches between PA gillnet and PBS gillnet. Catches of herring according to the thickness of net twine was the highest at No.2 and the thicker net twine tends to decrease the catches.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.78-82
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• 2009

We describe a catch experiment and the size selectivity of gill nets for male Japanese sandfish (Arctoscopus japonicus) caught near Gosung, Korea. The experiment, which was conducted between October and December 2007, examined six different mesh sizes: 36.4, 39.4, 45.5, 51.5, 53.0, and 57.6 mm. The catch was mostly Japanese sandfish (91.3%) and some others (8.7%). More male Japanese sandfish were caught with smaller mesh sizes and more females with larger mesh sizes. Relationships between the weight and fork length of the male and female Japanese sandfish were obtained. The relationship between the catch (Y) and mesh size of the gill net (X) was $Y=0.1773X^3-5.3753X^2+40.042X+26.846$ ($R^2=0.99$). The selection curve for male Japanese sandfish caught in the experiment was fit, via Kitahara's method, to a polynomial equation, which was $s(R={\exp}\{(-2.1391\;R^3+24.294\;R^2-88.289\;R+105.5)-5.180\}$, where R=l/m, and l and m are the fork length and mesh size, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.834-840
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• 2019

Recently, due to increased tourism and leisure activities, falls by fishers from coastal wave-dissipating blocks (breakwaters) in Korea have been rising. We investigated the optimal mesh size for use in safety nets designed to cover Tetrapod (TTP) breakwaters to prevent casualties from falls. This is a prerequisite for considering the scale and economics of safety net facilities. The optimal mesh size was determined based on the fisher gender and age, and the bodily features of Koreans. The optimal mesh size was found to be 18.6-27.0 cm, derived based on the femoral length and chest circumference.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.245-256
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• 2006

Fish community in the Hoengseong Reservoir was investigated from April to October 2005. The total number of fish caught from the period was 8,626 fish representing 22 species and 8 families, using tyke net and trammel net. Besides biomass was 122.9 kg. In the fyke net, 8,168 individuals caught during the period represented 21 species belonged to 8 families, its biomass was 90.6 kg. On the other hand, 458 individuals caught in the trammel net during the period represented 16species belonged to 6 families, its biomass was 26.3 kg. The results showed that the trammel net had lower number of species, individuals, and less biomass compared to those of the tyke net. Number of species confirmed was increased according as mesh size of the net was smaller. Besides, the fyke net with small mesh size was able to collect not only small-sized fish but also large-sized fish so that it was suitable to study qualitative and quantitative analysis of fish fauna in detail. Whereas, the trammel net with proper mesh size was effective to determine composition of fish species in the studied area.

• 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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.279-286
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• 2018

The objective of this study was to quantitatively evaluate the influence of the netting hanging ratio on fishing performance of gillnet. A total of six tests was carried out using three kinds of gillnets with different horizontal hanging ratios (0.3, 0.5 and 0.7) on the basis commercial gillnet of mesh size of 60 mm used in Yeosu Dolsan. As a result of the test fishing operation, catches of the net with hanging ratio 0.3 and the shortest float length was 1.34 times larger than the net with hanging ratio 0.7. The caught species in experimental testes was lager in the net with hanging ratio 0.3 than the net with hanging ratio 0.7. The catch rate per unit area (CPUE) is on the silver croaker with the largest catches in tests as follows. The net with hanging ratio 0.3 net was $89.45g/m^2$, hanging ratio 0.5 net was $41.63g/m^2$, and hanging ratio 0.7 net was $24.50g/m^2$. The net with hanging ratio 0.3 (float line length of 45 m) exhibited the largest CPUE value.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.302-311
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• 2015

A series of field tests to estimate the size selectivity of monofilament and multifilament gill net for marbled sole, Pleuronectes yokohamae, were carried out 12 times with five different mesh sizes (86.6, 101.0, 121.2, 137.7 and 151.5mm) in the western sea of Korea from 2007 to 2009. The master selection curve was estimated by the extended Kitahara's method. The total number of catch species was 23 and that of catch was 1,688 in the field tests. Marbled sole of total catch was 1,150 with 68.1 percent. In the monofilament trammel net, the optimum value of total length (TL) per mesh size (m) for 1.0 of retention probability was estimated 0.280 and the values of TL/m were estimated to be 0.187, 0.201, 0.210, 0.218 and 0.226 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. In the multifilament trammel net, the optimum value of TL/m for 1.0 of retention probability was estimated 0.307 and the values of TL/m were estimated to be 0.195, 0.211, 0.222, 0.232 and 0.241 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively.

• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.61-69
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• 2008

Using empirical data of fish performance and physiological limits as well as physical stimuli and environmental data, a cod-end selectivity model based on a chaotic behavior model using the psycho-hydraulic wheel and neural-network approach was established to predict fish escape or herding responses in trawl and cod-end designs. Fish responses in the cod-end were categorized as escape or herding reactions based on their relative positions and reactions to the net wall. Fish movements were regulated by three factors: escape time, a visual looming effect, and an index of body girth-mesh size. The model was applied to haddock in a North Sea bottom trawl including frequencies of movement components, swimming speed, angular velocity, distance to net wall, and the caught-fish ratio; simulation results were similar to field observations. The ratio of retained fish in the cod-end was limited to 37-95% by optomotor coefficient values of 0.3-1.0 and to 13-67% by looming coefficient values of 0.1-1.0. The selectivity curves generated by this model were sensitive to changes in mesh size, towing speed, mesh type, and mesh shape.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.916-922
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• 1997

This paper attempted to estimate mesh selectivity of gill nets for neon flying squid in the north Pacific Ocean. The 11 linear regressions, (P<0.05) were obtained using the data on catch ratios derived from mesh size combinations between two slightly different mesh sizes of 12 kinds of research gillnet (namely 33, 37, 42, 48, 55, 63, 72. 76, 86, 96, 105 and 115 mm in stretched mesh size). There was an increase in the optimum length with the increase in mesh size but standard deviation showed somewhat increase with the increase in the mesh size. The selectivity curves were well fitted to the length frequency distributions obtained from samples for the mesh sizes from 48 mm through 86 mm. For the mesh sizes of 33, 37 and 42 mm the DML (Dorsal Mantle Length) compositions were distributed towards the right hand-limb of the curves. The DML distributions from the 96 mm and larger meshes showed a trend towards the left hand-limb of the curves. The selectivity curves for different mesh sizes indicate that large mesh sizes catch a greater size range of squid, and the gill net fishery in the north Pacific Ocean captures effectively neon flying squid within the range of $9\~43cm$ DML.