• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.1
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• pp.9-16
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• 2016

This study was conducted to analyze fishing capacity and bycatch by mesh size and entrance size of spring net pot conducted by water tank and field experiment. The water tank experiments were conducted by using traps with mesh size of 22 mm and entrance size of 120 mm and 140 mm, respectively in the water tank of NIFS. The field experiment was conducted using 5 kinds of spring net pot with mesh sizes of 20 mm, 22 mm, 35 mm and entrance size of 120 mm, 130 mm, 140 mm, 360 mm by coastal trap fishery vessel operating around the area of Geoje island. In the result of water tank experiments, the catch of conger eel was 1.5 times higher when using trap with entrance size of 140 mm than that of 120 mm. In the field experiment, when using same mesh size, the larger the entrance size, the higher amount of conger eel catch, bycatch and number of bycatch species. When using the same entrance size, the larger the mesh size, the lower amount of conger eel catch and number of bycatch species, whereas the amount of bycatch showed increasing trend.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.3
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• pp.195-203
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• 2010

Recently, Fishermen have required to expand the circumference of trap entrance for conger eel because it was difficult to take the catch out as well as to put the baits into. A series of fishing experiments was carried out in coastal areas of Tongyoung, Korea in 2008 and 2009 using the traps to describe the effect of the entrance size on the catch. The experimental traps (five types) were used in filed experiments with four types circumference size traps (140, 180, 220 and 260mm) with mesh size 22mm and another type was used the same one usually using in filed with mesh size 35mm (750mm circumference). The experiment results were, the conger eels of total length 35mm more or so were caught 85, 93, 142 and 176 individual by the experiment traps with mesh size 22mm as increase circumference size from 140mm to 260mm, respectively. And the small conger eels of the total length below 35mm to be prohibited to catch by law were caught 145, 160, 288 and 304 individual according to increase the circumference size of trap, respectively. In addition, in case of the trap with mesh size 22mm, bycatches were 230 - 260 individuals and much more than bycatches of the trap with mesh size 35mm. In conclusion, when we expand the circumference size of trap according to fishermen's requirement, we should review not only economic of fishery but also increasement the bycatch of non-target fishes and small size fishes.

• Applied Microscopy
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• v.40 no.4
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• pp.237-244
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• 2010

Utricularia forms small, but complex carnivorous trap along the stem either in water or in soil depending upon species. The shapes and sizes of the traps, appendages, and trichomes are known to differ among aquatic, terrestrial and epiphytic species. In the present study, the morphology and microstructure of the trap in aquatic Utricularia japonica and terrestrial U. livida were examined using light and electron microscopy. The aim of this study was to compare the characteristics of trap features between the aquatic and terrestrial species. The trap was found to be comprised of a thin walled bladder with numerous capitate trichomes, two-armed bifid and four-armed quadrifid glands in both species; however, the traps of the two species were different in size, and number and morphology of the trichomes and glands. Aquatic Utricularia was chlorenchymatous with chloroplasts distributed throughout the body, whereas the terrestrial species was translucent without plastids due to an adaptation to underground habitats. Furthermore, the former differed considerably in that the traps developed antenna and appendages around the entrance area. A peculiar trap entrance was also noted in U. livida, which exhibited radiating rows of various trichomes within funnel-shaped tissue. A large number of glandular trichomes covered the entrance area and door surface with four trigger hairs each in the aquatic form but only two in the terrestrial form. The glandular trichomes near the door secreted a large amount of mucilage that temporarily composed the velum in the U. japonica, however, it was not observed in the terrestrial species. All of the aforementioned features were highly related in their structure and function during carnivorous mechanism in Utricularia. The current findings provide important data for further comparison of the different life forms within Utricularia.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.85-91
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• 1983

The behaviour of shrimp in response to the trap was much influenced by the type, size and the dimensions of entrance as well as physiological and ecological conditions. The entry and the escape behaviour of shrimp to the model trap were observed in accordance with netting materials, baits, type and slope of entrance, and gathering response were also investigated on the odour of bait extracts in the aquarium from June to August, 1983. Entering shrimp to the circular entrance was significantly more than to the triangular or the square; however, no differences were found in the entry behacior among netting materials i e., P. A, P. E. and cotton. According as the slope of entrance was increased its angle from 0$^{\circ}$ to 90$^{\circ}$, number of entering shrimp was decreased; however, number of escaping shrimp at 30$^{\circ}$or 60$^{\circ}$ with time was fewer than at 0$^{\circ}$ or 90$^{\circ}$. Gathering responses of shrimp on the odours were more sensitive to the flesh of mackerel or the shrimp than to the pickled anchovy, or the pettitioes, while no differences were found between another bait extracts, i e., the shrimp and the flesh of mackerel, the short-necked clam and the horse mackerel, the flesh and the viscera of mackerel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.61-70
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• 1986

In accordance with a rapid growth of demani on aquatic animals, researches of the unused fishery resources On the deep sea b~d in the Korean Waters has been and will be required. The authors carried out a series of fishing experiments to investigate the available resources and to find the effective fishing method on the deep sea bed of the Korean East Sea. In the experiments, 19 kinds of traps which are different from each other in shape, mesh size and entrance diameter were used. The fishing experiments w~r;; carried out in four areas of 20Dm, 600.'11, 800m and 1000.'11 deep respectively, by the Pusan 402 (30:) GT) and the Pusan 403 (279GT), the training ships of National Fisheries University of Pusan, during August, 1986. The catc~ were analyzed with the size, the depth and the construction of traps. The results obtained can be summarized as follows: 1. Main species of the catch w~re pink shrimp, Pandalus bolelis, a kind of welks, Buccimum striatissimum and a kind of larg~ crabs. Chiono8cetes japonicus and the another species were few. 2. The CPUE value (expressed by the number of catch per trap in this paper) of pink shrimp was the highest in the depth of 20J-n around, and the value in the depth of 600.'11 or more decreased gradually with an increase of the depth. But, the value of Buccimum straitissimum was much higher in the depth of 6:J:)!1I or more than that in the depth of 200m around. On the other hand, the value of Chion:Jecetes japonjcus was very low in general. 3. The iniividual body size of the catch differed with the depth. Pink shrimps caught in the depth of 200m around were smaller than those in the depth of 600.'11 or more. In contrast with this, Baccimum striatissim:t.m caught in the depth of 200m around were larger than those in the depth of 600.'11 or more. 4. Depending on the selection curve in Ishida's method for the mesh size of trap webbing, the carapace length of pink shrimp and the shell length of Buccimum striatissimum which are equivalent to 100% relative catching efficiency can be estimated about 3.5cm and 6.5cm or so respectively. 5. The number of catch of pink shrimp and Buccimum striatissimum by the 60.'1'1.'11 entrance diameter of trap were less than that by the 90mm, 120mm and 150mm, even thogh the diffierence am~r, g 9:Jmm, 120.'11.'11 and 150:1'.'11 are not so large.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.247-254
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• 2004

The mesh selectivity of the drum net fish trap for elkhorn sculpin(Alcichthys alcicornis) in the estern sea of Korea was described. The selection curve for the elkhorn sculpin caught from the experiments between June 2003 and December 2003 was by SELECT(Share Each Length Class's Catch Total)model and by Kitahaa's method to a polynomial equation and two parameter logistic selection curve. The selection curve by SELECT model showed to be equal probability of entrance of the elkhorn sculpin in the large(55mm) and small(20mm) mesh traps by minimum AIC (Akaike Information Criteria). The equation of selectivity curve obtained by Kitahara's method using a logistic function with least square method was $s(R)\;=\;\frac{1}{1+exp(-0.3545R+2.141)$, where R=1/m, and/and m are total length and mesh size, respectively. The mesh selectivity curve showed that the current regulated mesh size(35mm) for the trap was corresponded to 21.4cm in the $L_{50}$of the selection curve for the elkhorn sculpin.