Bong-Jin Cha

Development and physical properties on the monofilament for gill nets and traps using biodegradable aliphatic polybutylene succinate resin

This study was aimed not only to develop the gill net and trap made of biodegradable monofilaments in order to prevent a ghost fishing and to protect marine ecosystem, but also to analyze their spinning process and physical properties. Results showed that the spinning speed of biodegradable polybutylene succinate(PBS) monofilament was estimated to be approximately 100m/min when spinning temperature and cooling water temperature were adjusted at and , respectively. The breaking loads of PBS monofilaments were estimated to be at , at , and at in the dry condition, respectively. However, its breaking loads in the wet condition were reduced by 2.4-5.5%, compared to those in the dry condition. The knotted strength of PBS monofilament at was estimated to be 98.6% of PE in the dry condition. The breaking load of PBS monofilament at was evaluated to be 81.8% of PA, and its softness showed 3 times less than that of PA in the wet condition. The breaking load of PBS monofilament at was 95.3% of PA, and its softness showed 1.6 times less than that of PA in the wet state. However, the load elastic elongations of two kinds of monofilaments were estimated to be 1% higher than that of PA.

The development of basic structure of jellyfish separator system for a trawl net

The purpose of this study is to develop the jellyfish separator system(JSS) for reducing fishery damage bythe increase of jellyfish in the sea area of Korea in summer. First of all, to find the optimum structure of aJSS, six types of JSS in trawl fishery were designed and manufactured, the underwater shape of JSS and theseparating process by JSS were observed in the circulating water channel(CWC). And the field experimentswere carried out in July and September 2004 in the southern sea of Korea. For the moving path of thejellyfish model in the CWC, in case that the model was larger than the mesh size of the separator net, it wasguided toward the lower part of the separator net by the guiding net and discharged through the outlet. Incase that the model was smaller than the mesh size of the separator net, some models which passed throughthe upper part of the guiding net were smaller than the mesh size of the guiding net and discharged throughthe outlet and most of the model which passed through the lower part of the guiding net moved to the cod-end passing through the separator net. According to the field experiment result, the optimum tilt angle ofseparator net was inferred 20that the discharge rate of jellyfish was higher than the other tilt angle ofseparator net and the optimum structure of JSS was inferred GS type(consists of guiding net and separatornet) that the discharge rate of jellyfish was higher than S type(consists of separator net). It was demamded tocarry out more study for the countermeasure to reduce loss of fish.Key words : Trawl, Jellyfish, Separator system, Guiding net, Separator net

Comparison of fishing gears and catches by areas in the Gape net with wings in Jeonnam, Korea

서 론 낭장망 어업은 조류의 흐름이 빠른 해역에 날개그물 이 있는 자루그물을 말뚝이나 닻으로 고정 부설하여 조 류를 따라 회유하던 수산생물이 자루그물 속으로 들어 가도록 하여 어획하는 어업으로 우리나라 서해와 남서 해역을 중심으로 발달하였다. 낭장망 어업의 최근 10년간 생산량 변동을 살펴보면, 2003년 6,451톤에서 점점 증가 추세를 보이다가 2008년 18,988톤을 정점으로 생산량은 점점 감소 추세에 있다. 지역별 생산량은 전라남도 지역이 우리나라 전체 어획 량의 79.1%로 가장 많은 어획량을 차지하고 있으며, 지 역별 낭장망 허가건수로는 진도군이 489건으로 전국에 서 가장 많으며, 다음으로 완도군, 여수시 순으로 나타 났다 (KOSTAT, 2012). 우리나라 연안에서 멸치 등을 어획하는 낭장망 어업 은 조류를 이용하는 어업이므로 유영 능력이 크지 않은 어류나 갑각류, 두족류가 어획되나, 현실적으로는 멸치 의 회유량이 많고 경제성도 높으므로 끝자루 부분에 세 목망을 사용하여 조업하고 있는 실정이다. 따라서 세목 망을 사용하는 낭장망 어업에서는 멸치 (Engraulis japon전남지역 낭장망의 어구 및 어획물 비교

Catching efficiency of biodegradable trammel net for swimming crab (Portunus trituberculatus) in the Yeonpyeong fishing ground of Korea

To study the catching efficiency of biodegradable trammel net for swimming crab (Portunus trituberculatus), three types (biodegradable, monofilament and multifilament) of trammel nets were used in the field test, and the tests were carried out 16 times with two different mesh sizes (105mm and 160mm) in the Yeonpyeong fishing ground of Korea, 2009~2011. The catching efficiency of three type nets was analyzed by catch in number, catch in weight and average weight per individual of small and large size swimming crab by net types and mesh sizes. Statistical T-test was also carried out to verify the efficiency between the three types of nets. The results are as follows. The catch in number of swimming crab was 24,667 and formed about 81.0% of total catch. Of all swimming crab catch, small swimming crabs with less than 64mm in carapace length which is a prohibited landing size by law formed 48.1%, larger swimming crabs with more than 64mm in carapace length which is a landing size formed 51.9%. In 105mm mesh size trammel net test, the catch share in number of small size swimming crab by biodegradable trammel net was 47.5% in comparison with multifilament trammel net and 74.2% in comparison with monofilament trammel net, so biodegradable trammel net has more protective effects on small size swimming crab than other types of trammel nets. The protective effects for small size swimming crab by biodegradable trammel net was 25.8~52.5% in comparison with other types of trammel nets. The catch share in weight of large size swimming crab by biodegradable trammel net was 98.3% in comparison with multifilament trammel net and 92.3% in comparison with monofilament trammel net, so biodegradable trammel net has a similar catch efficiency to multifilament trammel net. The results of 160mm mesh size trammel net test have shown similar results of 105mm mesh size trammel net test. This study shows that biodegradable trammel net is a more useful fishing gear than multifilament and monofilament trammel net because biodegradable trammel net has lower catch rate than other types of nets in small size swimming crab and similar catch rate than multifilament trammel net which is a well used net by fishermen.

Relative efficiency of monofilament and multifilament nylon gill net forMarbled sole (Pleuronectes yokohamae) in the western sea of Korea

To estimate the mesh selectivity of monofilament and multifilament gill net for Marbled sole, Pleuronectes yokohamae, the field testes were carried out 12 times with five different mesh sizes (86.6, 101.0, 121.2, 137.7, 151.5mm) in the western sea of Korea, 2007-2009. The master curve of selectivity was estimated by the extended Kitahara`s method. In the field testes, the total number of species and catch were 26 and 987, respectively. The catch number of marbled sole was 728 and occupied 73.8% in total catch. The optimum values of l/m for 1.0 of retention probability in monofilament and multifilament gill net were estimated 0.288 and 0.307, respectively and l/m was estimated to be 0.189, 0.203, 0.213, 0.222 and 0.230 in case of monofilament gill net and 0.171, 0.191, 0.205, 0.216 and 0.227 in case of multifilament gill net when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. The 0.5 selection range of multifilament gill net was wider about 1.5 times than that of monofilament gill net according as multifilament gill net was 0.216 and monofilament gill net was 0.148. So the multifilament gill net has a low selectivity than that of the monofilament gill net. To estimate the optimum mesh size on first maturity length 19.5cm of marbled sole, the retention probability value of 0.1 was adopted in consideration of using the gill net for marbled sole at present. The optimum mesh size were estimated to be 103.2mm and 114.0mm in monofilament gill net and multifilament gill net, respectively, on first maturity length 19.5cm of marbled sole.

Size selectivity of the dome-shaped pot for whelk Buccinum opisthoplectum in the eastern coastal waters of Korea

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.

The study on the Anchovy`s (Engraulis japonica) reaction to several light colors in a tank

This study was conducted to develop energy-efficient LED lamps with an excellent fishing performance for an anchovy scoop net by comparing the functions of 6 different lamps- incandescent, blue LED, green LED, white LED, yellow LED and red LED lamp. We used incandescent and red LED lamps only for the initial test and then excluded because those showed the lowest herding capacity. According to the result, yellow LED showed lower herding capacity in comparison with the blue, green and white one. Although the herding performance of the blue, green and white LED was similar in almost tests, herding speed to the each light was different. The anchovies were gathered into the blue LED as the speed of 39.88cm/s that was the fastest. Green LED was the second as the speed of 33.28cm/s. White LED was the slowest as the speed of 26.73cm/s. We will have field tests because we found the result that yellow LED`s herding performance was better than green LED`s for 5 seconds comparing after starting in some tests.

A study on the bycatches by mesh size of spring-net-pot in Geo-je & Tong-young waters of Korea

Test fishing was carried out using six kinds of different mesh sizes (20, 22, 24, 28, 35, 40mm) for spring-net-pot to study bycatches according to the mesh size and catches survey was done for another one (meshsize : 22mm, entrance round : 350mm) in Geo-je Tong-young waters of Korea. On the first seaexperiment, it was thought that suitable mesh size of spring-net-pot catching conger-eel over 35cm withdecreasing the catches of conger-eel (

Catches comparison according to the codend mesh size of stow net on anchor in the West Sea of Korea

Experimental fishing was carried out to compare fishing status according to the codend mesh size (raschel,15mm, 25mm, 35mm, 45mm) of stow net on anchor in the coastal waters of Seocheon after manufacturingfive kinds of fishing gears and commercial fishing boat (7.93 tons) was used for it. Total catches of raschel,15mm, 25mm, 35mm, 45mm codend were 816,949g, 203,994g, 1,405g, 51,576g, 194g in September and40,545g, 66,974g, 14,692g, 12,647g, 12,655g in October. Dominance species were anchovy (

Development of the biodegradable octopus pot and its catch ability comparison with a Polyethylene (PE ) pot

Biodegradable octopus pot was developed to reduce plastic pollution problem in the sea and fishing troublebetween fishermen . It can be expect to recycle other wasted biodegrade fishing gear . Experimental fishingwas carried out to understand the difference in fishing efficiency between Polyethylene (PE ) octopus potsand biodegradable (Polybutylene Succinate and Polybutylene adipate -co -terephthalate ) octopus pots whichwas tried to make in this study in the sea . There were caught by 237 numbers of fishing during theexperimental period . Among the 237 numbers of fishing , 160 or 67.5% were PE pots which were more thanthe biodegradable pots . A comparison of the monthly catches between the PE pots and biodegradable potsshows that the catches were overall higher in the PE pots than in the other pots . The result is very similarwith the comparison of total catches by each type of the pots . In terms of bycatch , the number of species ,amount of catches and the number of fishing with bycatch were more significant in the biodegradable potsthan in the PE pots . Keywords: Biodegradable , Polybutylene -succinate (PBS ), Polybutylene adipate -co -terephthalate (PBAT ),Octopus trap , Catch ability