Gun-Ho Lee

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.

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 (

Catching efficiency of biodegradable trap for swimming crab (Portunus trituberculatus) in the western sea of Korea

To investigate the catching efficiency of a biodegradable round trap for a swimming crab (Portunus trituberculatus), four types of material (two types of biodegradable net, one type of biodegradable plus polyethylene net and one type of polyethylene net) for traps were used in the field test, and the field tests were carried out 11 times in the Boryeong fishing ground of Korea, 2012~2013. The catching efficiency of four type traps was analyzed by catch per trap, weight per trap and mean weight per individual of small and large size swimming crab. Statistical Kruskal-Wallis test was carried out to verify the significant difference for the efficiency between types of material. The catch in number of swimming crab was 9,015 and formed about 94.3% of total catch. In the results of catching efficiency of traps, there was a little difference in catch per trap, weight per trap and mean weight per individual of swimming crab in-situ data. But there was no significant difference in catching efficiency between the biodegradable traps and the PE trap (P>0.05), so it`s needed to use widely a biodegradable trap for the conservation and sustainable management of swimming crab resources.

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

Development for auto lightening buoy system using solenoid

This study investigates the development of an automatic lightening buoy that can indicate an aquaculture cage at night or in rough weather. The energy for the light is generated by the linear motion of a magnet along with a coil inside the buoy as the waves cause the buoy to oscillate up and down. The principle of the magnet motion is different between the magnet and body of the buoy because the movement of the latter is dependent on the surface wave, while the former is affected by the damper. To obtain a quantitative performance of the buoy, the voltage as well as up and down motion produced by several waves were measured in the wave tank. A shorter wave period, i.e., faster motion, of the magnet produced a brighter light. It is expected that this study can aid in deciding the optimum design of a buoy capable of producing a bright light at any aquaculture site affected by sea or fresh water waves.

Analysis of submerging characteristics and stability of the model submersible fish cage operated by buoyancy control

This study aims to analyze the performance of a submersible fish cage which was designed for developing an economical cage system can be applied in korean aquaculture environment easily . To analyze the performance of the designed cage a model test was carried out . In the test , inclination changes of the upper frame and mooring tensions of model cage were measured during the submerging and surfacing motion in still water and wave condition (period : 2 s, wave height : 0.1, 0.2, 0.3 m). As a result , in the still water condition the model cage kept horizontal balance and inclination degree of the upper frame was about 1。 . In the wave condition , the model cage showed bilateral symmetric up-and-down motion but the average inclination degree of the upper frame was about 0 。 . When the model cage reached at a depth of 1m, the upand-down motion of the cage was decreased by 12% compared with that of at the surface (period 2s, height 0.3 m). In the same wave condition , the maximum and average line tension under the bottom position were about 8% and 11% respectively compared with that of at surface .

Difference of tension on mooring line by buoy type

자망 및통발 어구의 구성 요소 중하나인 부이는 어구구성 특성상 해수면에 위치하기 때문에 풍랑이 발생할때파랑의 영향을 직접 받는 부분이다 우리나라 연안에서 사용하는 자망과 통발 어구는 보통 부이를 수면에띄우고 부이줄을 연결한 뒤그물 또는 모릿줄을 부이줄끝에 연결하여 어구를 전개하는 구조로 되어 있다 일반적으로 파랑의 영향은 수심이 깊어질수록 감소하므로 자망어구의 그물부나 통발 등의 모릿줄 등과 같이수면 아래 설치되는 요소들은 부이에 비해 파랑의 영향을 적게 받는다 따라서 부이는 파랑 발생 시어구의위치나 구조에 많은 변화를 주는 요소 중하나로 볼수

Mesh selectivity of multifilament nylon gillnet for ocellate spot skate (Okamejei kenojei) in the western sea of Korea

To estimate the mesh selectivity of gillnet for ocellate spot skate (Okamejei kenojei), the field tests were carried out 12 times with six different mesh sizes (121.2mm, 137.7mm, 151.5mm, 168.3mm, 178.2mm, 189.4mm) in the coastal waters of Taean, Chungcheongnamdo of Korea, 2010~2011. In the field tests, the total number of species was 31, and that of catch was 1,410 and the total weight was 618,006g. The number and weight of ocellate spot skate which is main target in this study were 1,004 and 434,592g, respectively. The catch in number of ocellate spot skate occupied about 71.2% in total catch. The others of catch species were marbled sole (8.4%), sea raven (4.4%), japanese swimming crab (4.2%) and flatfish (4.1%) and so on. The range of body disk width (DW) of ocellate spot skates which were caught in this study was 15.2~35cm and the mode was 27~29cm. The estimation equation of mesh selectivity using the extended Kitahara`s method was expressed as s

Dynamic simulation of the behavior of purse seine gear and sea-trial verification

(R)