Sam-Kwang Cho

Mesh Selectivity of Durm Net Fish Trap for Elkhorn sculpin(Alcichthys alcicornis) in the Eastern Sea of Korea

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

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

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

Catch characteristics of the biodegradable gill net for flounder

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

There are many studies of the biodegradable net for fishing to prevent marine pollution in Korea and the snow crab gill nets is developed effectively. Recently, the biodegradable gill net for fishes is being developed. This study is the experiment of the catch characteristics for the biodegradable flounder gill net. The 8 experiments were carried out using the nylon gill net and the biodegradable gill net in from August to October, 2011 in the southern East Sea. The results obtained from the above approaches are summarized as follows; A total of 16 species was caught with most dominant species of Cleisthenes pinetorum followed by Liparis tanakai, Glyptocephalus stelleri, Buccinum striatissimum and Dasycottus setiger. A total of catch of the nylon net was 342,885g and that of the biodegradable net was 236,857g. Thus catch of the nylon net was 1.45 times more than that of the biodegradable net. The length composition of Cleisthenes pinetorum, caught by the biodegradable net was very similar to that of nylon. As a result of analysis on the effect of submerged time, small fish escaped more easily than large fish as the submerged time is getting longer. And catches of the biodegradable net was less than the nylon net`s as higher as wave height. Wave height was more influential factor for fishing capacity than submerged time based on the results of a comparison between catch difference of two kinds of gill nets and catch characteristics.

Entering behavior and fishing efficiency of common octopus, Octopus minor to cylindric trap

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

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.

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

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.

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

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.

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