• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.281-289
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• 2016

Spinyhead sculpin Dasycottus setiger, a species of cold water fish, is distributed along the eastern coastal waters of Korea. A series of fishing experiments was carried out in the waters near Uljin from June, 2002 to November, 2004, using the experimental monofilament gill nets of different mesh sizes (82.2, 89.4, 104.8, and 120.2 mm) to describe the selectivity of the gill net for the fish. The SELECT (Share Each Length's Catch Total) analysis with maximum likelihood method was applied to fit the different functional models (normal, lognormal, and bi-normal models) for selection curves to the catch data. The bi-normal model with the fixed relative fishing intensity was selected as the best-fit selection curve by AIC (Akaike's Information Criterion) comparison. For the best-fit selection curve, the optimum relative length (the ratio of fish total length to mesh size) with the maximum efficiency and the selection range ($R_{50%,large}-R_{50%,small}$) of 50% retention were obtained as 2.363 and 0.851, respectively. The ratios of body girth to mesh perimeter at 100% retention where the selection curve of each mesh size represented the optimum total length were calculated as the range of 0.86 ~ 0.87.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.274-280
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• 2007

The mesh selectivity of gill net for Japanese sandfish (Arctoscopus japonicus) caught in the East Sea, Korea was described. The experiment was conducted with five different kinds of mesh size (39.4, 45.5, 51.5, 53.0, 57.6mm) between November and December 2006 in spawning season. The catch was mostly Japanese sandfish (93.3%) and some others (6.7%), and almost all of the female Japanese sandfish were larger than the fork length at 50% maturity (16.7cm). The selection curve for the female Japanese sandfish caught from the experiments was fitted by the Kitahara's method to a polynomial equation which was $s(R)={\exp}\{(0.2584R^3-5.3445R^2+32.269R-59.868)-0.6585\}$ where R＝l/m, and l and m are fork length and mesh size, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.143-151
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• 2003

A series of fishing experiments was carried out in the waters off the east coast of Korea from January, 2002 to March, 2003, using gill nets of different mesh sizes (m = 180, 210, 240, 270, and 300 ㎜) to determine the size selectivity of gill net for male snow crab Chionoecetes opilio. The maximum carapace length (RL) of each male snow crab caught in the fishing experiment was measured. The master curve of mesh selectivity was estimated by applying the extended Kitahara's method. Two kinds of functional models, quadratic function and cubic function were used to express logarithmic selectivity curve and were fitted to the data using the method of least squares. The obtained results were summarized as follows; 1. The cubic function of asymmetry was chosen to determine the selectivity curve of gill net for male snow crab from the model deviance comparison. 2. The result of size selectivity showed that the catch number of small male crab was getting decreased according to the increase of mesh size. 3. The optimum value (RL/m) was 0.549 and the RL/m was estimated to be 0.281, 0.296, and 0.356 when the retention probability were 0.2, 0.25 and 0.5, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.506-510
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• 1985

It is an important work to determine the mesh size of gill net for efficient catch. For investigating the suitable mesh size, the gill net for anchovy, Engraulis japonica was made and operated in the bay of Ulsan in July. 1983. The gill net for anchovy was composed of six different mesh size, 23.1mm (H=0.65), 21.6mm (H=0.65), 20.0mm (H=0.65), 23.1mm (H=0.55), 21.6mm (H=0.55) and 20.0mm(H=0.55). The parts of body caught by the gill net was examined, and the selectivity curves (for reference Ishida's method) with respect to the each mesh size were estimated using the data obtained through the operation of research gill net. The main results of this study are as follows: 1. The number of anchovy whose neck was in net was 148, more than $90\%$ of all, 161 2. The coefficient of relationship between the circumference of neck and the fork length were 0.70. 3. Fork length that the relative fishing efficiency of 23.1 mm mesh size (H=0.55) was maximum value was about 11.1 centimeter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.174-180
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• 2003

This study investigated the size selectivity of the round traps for greenling (Hexagrammos otakii) in the western sea of Korea. The selection curve for the greenling from the experiments on Oct. 2000 and Ar. 2001 was fitted by Kitahara's method to a polynomial equation and two parameter logistic selection curve. The selectio curve of the latter was more reasonable than that of the former. The equation of selectivity curve obtained using a logistic function with least square method was , s(R)=1/1+exp(-1.1169R+6.4565), where R=1/m, and 1 and m are total length and mesh size, respectively. The size selectivity curve showed that the current regulated mesh size(35mm) in case of the round trap was close to the L50 (37.0mm) of the selection curve for the biological minimum length (21.4cm) of the greenling.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.368-376
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• 2013

Fishing experiments were carried out in the adjacent sea of Yeongil Bay, the eastern cost of Korea from 2003 to 2004 using the dome-shaped pots with different five mesh sizes (17.1, 24.8, 35.3, 39.8, and 48.3mm) in order to determine the size selectivity of pots for the whelk, Buccinum opisthoplectum. The catch species were composed of Buccinum opisthoplectum (45.4%), Buccinum striatissimum (30.1%), Pandalopsis japonica (9.3%), Chionoecetes opilio (8.9%), and so on. The shell height (l) of Buccinum opisthoplectum caught in the experimental fishing pots was measured. The SELECT (Share Each Length's Catch Total) analysis method was applied with fishing data to obtain master selection curve. The model with the estimated split parameter was found to fit the catch data best. The master selection curve was estimated to be s (R)〓exp (7.833R-10.871)/[1 + exp (7.833R-10.871], where R is the ratio of shell height to mesh size. The relative shell length for 50% retention was 1.388, and the selection range was 0.281. It means that the pots of larger mesh size allow more whelks of small size to escape.

• 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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.3
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• pp.189-195
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• 2023

This study quantitatively evaluated size selectivity for three netting shapes (T0; regular, T45, T90) and hanging ratio (35%, 70%) of T0 netting used for trawl codend. The size selectivity experiment was performed in a tank using a cube experimental model with a length of 50 cm on one side and 389 experimental individuals, jack mackerel (Trachurus japonicus). In the selectivity analysis, a selectivity curve was created based on the selection ratio using a logistic function, and the 25%, 50%, and 70% selection length and selection range (SR) were obtained. The T0 netting was 19.54 cm when the 50% selective length, which is a selectivity evaluation index, had a hanging ratio of 35%, a selection range of 0.51 cm, and 22.70 cm and 3.08 cm for the hanging ratio of 70%. The T45 netting was 24.34 cm and 2.13 cm, and the T90 netting was 23.51 cm and 2.84 cm. The results of the T45 netting and the T90 netting are similar, and the 50% selection length and selection range were relatively larger than the T0 netting. There was a significant difference in the correlation between the circumference of the inner circle of the mesh by the shape of the netting and the body girth of the experimental individual (Pearson test, r = 0.86, p < 0.05). There was no significant difference in the correlation between the selection ratio by the T0 netting, T45 netting, and T90 netting with a 70% hanging ratio (one-way ANOVA, p > 0.05). The results of this study showed that selectivity such as T45 netting and T90 netting appeared when the hanging ratio, which maximizes the area of T0 netting, was maintained at 70%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.161-171
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• 1994

Mesh selection analysis for the trawl net were carried out at the Southern Korean Sea and the East China Sea during the 1992-1994 years by the training ship Seabada of the National Fisheries University of Pusan, using A type (51.2mm), B type (70.2mm), C type (77.6mm), D type (88.0mm) square mesh cod-ends. The fishing trials were made using bottom trawl of the trouser type cod-end with cover net. Selection curves and selection parameters were calculated by a logistic model for Sphyraena pinguis, Pampus argenteus, Trachurus japonicus, Pagrus major, Callanthias japonicus, Trichiurus lepturus. The results obtained are summarized as follows: 1. Red barracuda : Selection range and fifty percent selection length in the A type was 115.8mm, 292.8mm, respectively. 2. Harvest fish : Each selection range and fifty percent selection length in the B. C. and D type was 37.7mm, 113.8mm : 40.1mm, 131.7mm and 64.8mm, 148.6mm, respectively. Selection parameters of master curve were : slope, 3.81 : intercept, -6.4. Optimum mesh size was 89.3mm. 3. Horse mackerel : Each selection range and fifty percent selection length in the A, B, C and D type was 43.0mm, 148.3mm : 60.7mm, 183.2mm, 214.5mm and 91.4mm, 254.9mm, respectively. Selection parameters of master curve were : slope 2.30 : intercept, -6.4. Optimum mesh size was 66.8mm. 4. Red seabrem : Selection range and fifty percent selection length in the D type was 42.7mm, 203.4mm, respectively. 5. Yellowsail red bass : Selection range and fifty percent selection length in the A type was 84.0mm, 110.6mm, respectively. 6. Hair tail : Each selection range and fifty percent selection length in the A, B and C type was 59.7mm, 176.0mm : 100.9mm, 250.7mm and 178.6mm, 307.0mm, respectively. Selection parameters of master curve were : slope, 1.54 : intercept, -5.4. Optimum mesh size was 57.5mm.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.3
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• pp.181-189
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• 2019

Discarding juvenile fishes under girth 16 cm nearly equal to inner perimeter of codend mesh size collected by a cover net method in bottom trawl. The body size of the main five species (mackerel, horse mackerel, sea bream, melon seed and black throat seaperch) was measured for their body length, girth, weight, height and width and analyzed size selectivity. Frequency of penetrating fish as retention in a cover net was less than 40% of total number of juvenile discarding fish. The most of body length or girth of five species were significantly different between in the codend and in the cover net. The 50% selection girth in the cover net ranged 8-11 cm were smaller than those in the codend ranged 9-13 cm by the species respectively. The 50% selection body length was significantly related with the ratio of body height (H) by body width (W) both for in the codend or in the cover net while 50% selection girth was not significantly related with H/W. Furthermore 50% selection fish size by fish species between in the codend and in the cover net was not significantly different both in body length or girth. Therefore, the girth selectivity represented possibly as one unique value regarding fish body shape was considered as more useful method for multi-species catch in trawl.