• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.1
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• pp.11-18
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• 2006

The behavior patterns of common octopus, Octopus minor to a cylindric trap were examined in the water tank using a video camera in order to know entering mechanism to the trap and to improve it. Fishing efficiency by 2 kinds of traps(A: 3 entrances, B: 2 entrances) was investigated in the coastal area of Deugryang Bay from May to July, 2005. Common octopus tends to approach by swimming more than walking towards trap. When they approached to the trap, they showed much more behaviors that sate at the around than upper part of it. Approaching behaviors of common octopus was more vigorous at nighttime than daytime on the trap, they showed the most vigorous action between 2 am and 4 am of the day. The rate of staying 30 seconds over around the trap was 41.5% in the nighttime. CPUE(g/trap) of common octopus caught by A type trap was 21.4% higher than the B type trap but there was no difference on the significance level of 5% by the ANOVA. Catch rate of common octopus and by-catch species caught by the A type trap were 97.2%, three and 98.7%, two for B type trap, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.2
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• pp.97-106
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• 2018

The objective of this study was to estimate physical properties and fishing performances of net twine with improved PBS copolymer resin (Bio-new), the existing PBS/PBAT blending resin (Bio-old) and commercial Nylon (Nylon). The tensile strength of Bio-new monofilament was equal to Bio-old and the elongation of Bio-new was about 6 % higher than that of Bio-old in wet condition. The physical properties tests were carried out to estimate breaking load and stiffness in dry and wet conditions, respectively. In the results, the breaking load of Nylon netting was the highest whereas the elongation of Bio-new was 1.4 times higher than that of Nylon netting in wet condition. The breaking load of Bio-old netting was about 9.2 % higher than that of Bio-new netting. However, the elongation of the Bio-new netting was about 3% higher than that of Bio-old. The stiffness of the Bio-new compared to Bio-old was improved about 34 % in dry condition and about 32 % in wet condition. The filed experiments of the fishing performance were conducted with three kinds of drift nets with different netting materials in the coastal sea of Jeju. The each experimental drift net made of different materials showed the similar fishing performance. Bio-old drift net yielded less catches of small sized yellow croaker than other drift nets. The netting materials affected the fishing performance and length distribution of catches in the drift nets.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.95-100
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• 2005

In order to improve the gill nets for croaker, Miichthys miiuy which is proper to the fishermen's income ans fisheries resource management, we had studied to the net height of present gill nets (mesh size 160mm, 50 mesh in depth), experimental gill nets-I(mesh size 150mm, 68 mesh in depth) and experimental gill nets-II(mesh size 142mm, 75 mesh in depth) in wter using the gill nets design ans analysis simulation system, and then investigated and analyzed the catch efficiency of each gill nets through the field fishing experiments. The net height of emperimental gill nets-I and experimental gill nets-II in water were estimated respectively about 1.5 times and 1.3 times higher than present gill nets which the net height is about 3.5m as the results of simulation considering the current of fishing fields. Total number of croakers which were caught by the persent gill nets was 62(body length 300~1,200mm), total catch weight was 398.7kg (mean 0.6kg/sheet). Total number of croakers which were caught by the experimental gill nets- I was 68(body length 600~1,100mm), total catch weight was 391.6kg (mean 1.2kg/sheet). Total number of croakers which were caught by the experimental gill nets-II was 28(body length 400~900mm), total catch weight was 99.2kg (mean 0.3kg/sheet).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.4
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• pp.195-202
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• 2006

To determine the relative efficiency and mesh selectivity of gill net for the Pacific saury, Cololabis saira, a series of fishing experiments was carried out in the Northwest Pacific Ocean from August 13 to October 13 in 2002, using gill nets of different mesh size(30, 33, 35, 37, 39 and 42mm) constructed from two kinds of twine material(monofilament, twisted multifilament nylon web). The relative efficiency of two material gears was expressed as the ratio obtained by dividing monofilament catch by multifilament catch in number. The master selection curve of each material gear was estimated by applying the extended Kitahara's method. The catch of experimental gears is mostly Pacific saury(98.6%), Cololabis saira. The kinds of bycatch are common squid(0.7%), Pacific mackerel(0.6%), etc. Catch comparisons in the two gears showed that monofilament nylon nets are 1.7 times more efficient. The optimum values in monofilament and multifilament gill net for Pacific saury are 8.28 and 8.23, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.290-299
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• 2011

Field tests were carried out with five different mesh sizes (86.6, 101.0, 121.2, 137.7, 151.5mm) to study the relative efficiency of monofilament and multifilament gill net for Marbled sole, Pleuronectes yokohamae, in the western sea of Korea, 2007-2009. The relative efficiency was analyzed by length distribution, catch in number, catch in weight and weight per individual for Marbled sole. Statistical T-test was done to verify the efficiency between two gears. In the field tests, the total body length range, catch in number and weight of Marbled sole was 15.8-48.2cm, 728 and 254,939g, respectively. During the field tests, Marbled sole less than 15cm length which is prohibition size of fishing was not caught, but the caught number of Marbled sole less than 19.5cm length which is first maturity length was 13 (1.8%) and the caught number of Marbled sole more than 19.5cm was 715 (98.2%). Catches of monofilament gill net was average 1.4 times more efficient than multifilament gill net. The weight per individual and total length by mesh sizes in the two gears tended to gradually increase according to mesh size increasing. But there was little difference of weight per individual and total length by mesh sizes between two gears.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.2
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• pp.96-105
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• 2009

For an effective management of fisheries resources, we need fisheries informations necessary for the establishment of reasonable fishing effort and TAC distribution. We carried out fishing research using trammel nets in the coastal sea of Susan-port(Yangyang, Gangwondo, Korea) and Hupo-port(Uljin, Gyeongbukdo, Korea) and analyzed fishing power variation of the fishing gear in terms of species composition, condition and so on for both sites. A total of 29 species were caught with most dominant species of Hippoglossoides dubius followed by Pseudopleuronectes herzensteini, Lophius litulon and Alcichthys elongatus in Susan. The total number of species caught in Hupo was 37 species with most dominant species of Todarodes pacifius followed by Lophius litulon, Hexagrammos agrammus and Pseudopleuronectes herzensteini. CPUE of Susan fishing area per trammel net was 12.74 fish and 2.00kg on average, while it was 6.80 fish and 2.27kg on average for Hupo. The fishing power index for both sites was 1, placing the two fishing grounds in a same level.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.385-394
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• 2013

This study has conducted a comparative analysis on the fishing efficiency of LED fishing lamps by squid jigging vessels, the Yeongrak-ho (16 tons) and Somang-ho (9.77 tons), which operated during September and October 2010 and during October 2011, comparing with MH (Metal Halide) fishing lamp-equipped fishing vessels. This study has also examined vessel's fuel consumption level. The light powers of LED fishing lamps of the Yeongrak-ho and Somang-ho were 25.8kW and 32kW, respectively. Those of the MH fishing vessels, that is, the MH fishing lamp-equipped fishing vessels, were 105kW and 81kW, respectively. The average squid catch in number of an LED vessel, Yeongrak-ho, was 39.2% of the MH fishing lamp-equipped fishing vessels; however, that of the Somang-ho improved to 78.7% of the MH fishing lamp-equipped vessels. Average catch in number by Yeongrak-ho crew was 2.6 times more than catch in number by automatic jigging machines. Average catch in number by MH fishing vessel crew was 1.8 times more than that by automatic jigging machines. An LED vessel, Yeongrak-ho's fishing rate was 17.5%~152.2% of the MH fishing vessels, that is, 61.1% on average, in comparison of combined catch in number per automatic jigging machine and per crewmember. Somang-ho's fishing rate was 6.7%~127.6% of the MH fishing vessels, that is, 73.1% on average. The average fuel consumption level of the Somang-ho, throughout its departure from to arrival at the port, was 475.7l, and that during fishing hours was 109.6l, or 23.0% of the total fuel consumption level. Somang-ho's fuel consumption level per fishing hour was 9.7l on average.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.218-226
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• 2013

The objective of this study is to estimate the optimal net twine thickness of drift net for yellow croaker. The filed experiments of the fishing performance were conducted with three kinds of drift net with different monofilament diameters (No.3=0.284mm, No.4=0.330mm, No.5=0.370mm) the total eight times in the southwest coastal sea of Korea. And the physical properties tests on the monofilaments of experimental net were carried out to estimated breaking load and softness in dry and wet conditions, respectively. From the results, the No.3 mono. was the strongest break load per unit area in dry and wet conditions. And the softness showed that the No. 3 mono. was the most soft than another experimental monofilaments. The fishing performance was; the No. 3 drift net showed the most catches. Conversely, the catches of No. 4 and No. 5 drift net showed the half on the catches of No. 3 drift net. Consequently, the diameter of monofilament in the drift net for yellow croaker should carefully choose to consider the economic sides such as the amount of catches and the cost of catches.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.208-217
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• 2013

Decoys for automatic jigging machines, the body part of a squid hook, have been developed in small and existing sizes in consideration of squid food, color blindness, and retinomotor responses and in utilization of pearl pigment, PP of high transparency, and combined mixture. In comparison of the developed silver-white decoy and existing decoys, the optical characteristics were examined, and the fishing performance of small size silver-white squid hooks was assessed in application of 4 fishing boats with the squid automatic jigging machine and metal halide fishing lamp in July, 2012. The luminances of the three squid hook colors-green, dark green and silver-white-increased as the intensity of illumination increased. Among these, the increase of silver-white was particularly distinguished. As to the average contrast of squid hooks, that of silver-white was 10.33, which was the highest, and then green 1.86 and dark green -0.10 in the order. As to the fishing performance of the silver-white hook, that of the 202 Geumyeong-ho and 101Yongjin-ho which caught squids were similar to that of the existing green hook and was relatively low in the case of the Dongbu-ho. However, that of the Haengbok-ho which caught relatively small squids whose average length was 19.9cm and installed silver-white hook in all automatic jigging machines was significantly excellent. In order to enhance the fishing performance of small size silver-white hooks, therefore, it would be effective to install in every automatic jigging machines of fishing boat and to start fishing before July by which small squids are caught.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.292-301
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• 2010

For an effective management of fisheries resources, it is very important that to make clean inhabitation environment and to preserve fisheries resources. The material which is mainly used as fishing gear in modern times, is polyethylene, polypropylene, polyamide, etc., chemical fiber. And lost fishing gears which are make of these, occur ghost fishing and ocean pollution. To solve these problem, we development biodegradable fishing trap using the polybutylene succinate (PBS). Developed traps are for red snow crab (Chionoecetes japonicus) and shrimp, major traps in the East Sea, and we carried out fishing research using two kind traps in the coastal sea of Ayajin-port (Goseong) to analysis fishing efficiency of PE trap and PBS trap. As a result for fishing experiment (year 2005-2006) of red snow crab trap, two kind traps were almost the same in catches and length composition. During a experiment, parts of meshes, used for over 1 year, were cut by biodegradation. As a result for fishing experiment (year 2007) of shrimp trap, northern shrimp (Pandalus eous), coonstripe shrimp (Pandalus hypsinotus) and morotoge shrimp (Pandalopsis japonica) were catched, and the almost is northern shrimp. Two kind traps were almost the same in catches and length composition. In accordance with these result, it is recommended that the developed traps are have to commercialized because the fishing powers of PE traps and PBS traps were same. But biodegradation speed is have to controled in consideration of ocean microorganism volume and traps life.