In-Ok Kim

Effect of tooth spacing on the contact selection and available selection of a dredge for the equilateral Venus clam Gomphina melanaegis

The effect of various tooth spacing on the contact selection and the net-mouth available selection of a dredge for the equilateral Venus clam Gomphina melanaegis is evaluated by applying a contact-probability model based on the SELECT method to the data of paired-gear tests with a control dredge of 12-mm tooth spacing and four test dredges of tooth spacing 16, 20, 24 and 35 mm. A master selection curve was estimated to be s(R)=exp(−11.23R+4.799)/(1+exp[−11.23R+4.799]) where, R is l/d, the ratio of the shell length, l, to the tooth spacing, d. The shell width of 50% retention was slightly smaller than the tooth spacing, which means that size selectivity of teeth was a type of contact selection which was dependent on the tooth spacing. Contact probability, δ, of the clams coming into contact with the teeth were 0.625, 0.467, 0.563, 0.670 and 0.976 for tooth spacing 12, 16, 20, 24 and 35 mm, respectively. This indicates that some clams entered the dredge bagnet without contacting the teeth as the sand clogging the tooth spacing carried them into the bagnet. Available selection curve of the dredge net-mouth with teeth was obtained as δ s(R)+1−δ, and examined in terms of the legal landing size of the Venus clam.

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.

The performance of a wedge type jellyfish excluder device inserted in a trawl net

In order to describe the performance of a wedge type jellyfish excluder device, a series of fishing experiments was carried out in the coastal areas of Yokji Island, southern Korea in 2009, using a trawl net with a cover net. The body size and weight of each individual (fish or jellyfish) caught in the experimental fishing were measured. In the case of giant jellyfish the bell diameter and weight were measured. The catch species was composed of giant jellyfish (Nemopilema nomurai), silver croaker (Pennahia argentata), yellow croaker (Larimichthys polyactics), finespotted flounder (Pleuronichthys cornutus), largehead hairtail (Trichiuruslepturus), melon seed (Psenopsisanomala) and so on. The weight ratio and individual ratio of total fish escaped through the outlet of the excluder device were 0.322 and 0.320, respectively. The weight ratios of giant jellyfish excluded from the trawl net ranged from 0.740 to 0.921 (average 0.852/haul). It means that the wedge type jellyfish excluder device performed well and allowed the most of the giant jellyfish to exclude through the trawl net. The approximately 70% of fish entered in trawl net was caught. The wedge type excluder device needs some improvements to minimize the fish escape from the trawl nets in the future.

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 (

Hydroacoustic Survey of Fish Distribution and Aggregation Characteristics in the Yongdam Reservoir, Korea

국내 내수면은 하천의 수위 유지 및 농업용수 공급을 위한 보 부터 수자원의 효율적인 관리 및 발전소 운영을 위한 다목적 댐 에 이르기까지 다양한 규모의 수리 구조물이 축조되어 있다. 그 중 용담호는 2001년 용담댐이 준공되어 생성된 인공호수로 서 해안 지역의 효율적인 수자원으로 사용되고 있다. 2000년 이전 용담호는 얕은 수심 및 빠른 유속의 계류성 하천이었으나, 용담 댐 완공 이후 완만한 유속 및 정체로 인한 오염 물질의 퇴적 현 상으로 생태계 큰 변화가 진행되고 있는 수역이다(Lee et al., 2009). 특히 용담댐 건설 이후 서식지의 수몰로 인한 고유 어종 의 서식지 감소와 블루길과 배스 등 외래종의 유입으로 생태계 교란이 진행되고 있다(Yang et al., 2012). 국내에서 육상 담수역 및 해양에서 어류의 시·공간적인 분포 파악을 위한 조사는 1960년 이후 현재까지 주로 어구어업으로 진행되고 있다(Choi, 1971; Huh, 1986; Cha et al., 2004). 용담 호 또한 2000년 이후 낚시, 투망, 족대, 일각망 등의 어구 조사 를 통해서 어류의 종조성 및 분포 특성에 대한 연구가 진행되고 있다(Lee et al., 2009; Yang et al., 2012). 이러한 전통적인 채집 방법은 정성적인 자료 측면에서 많은 장점이 있지만, 한정된 채 집 면적 및 수층 제한성이라는 측면에서 정량적인 자료 도출에 오차를 만들어 낼 가능성이 높다. 정성 분석이 치우친 어구 채집 방법의 문제점을 극복하기 위한 방법 중 하나인 생물 음향 기법 은 1980년대 초 제시되어 국내에서는 1990년대 이후 주로 해양 생물의 분포 및 자원량 조사에 활발히 적용되고 있다(Kang et al., 2003; Lee et al., 2014). 생물 음향조사는 국외에서 해양 생태계뿐만 아니라 호수 및 저수지와 같은 담수 환경에서 어류 분포의 정량적인 평가와 대 상 어류의 모니터링 및 생태학에 관한 연구에 적용되고 있다 (Godleska and Jelonek, 2006; Knudsen and Larsson, 2009). 생물 음향 기법의 특징은 연구자의 주관을 배제시키고 사전에 설정된 음향 조사 정선으로부터 연속적이며 전 수층에 대한 객 수중음향기법을 이용한 용담호의 어류 분포특성 연구 이형빈·이경훈*·김성훈·김인옥·강돈혁

Mesh selectivity of a dome-shaped pot for finely-striate buccinum Buccinum striatissimum in the eastern coastal waters of Korea

)은수심 200 ∼500 =의사니질 어장에 분포하고 있다 (NFRDI , 2000 ; O;ED1>9 , 2000). 이종은 주로통발 어구에 어획되어 고가로 유통되므로 연안 통발 어업인들의 중요 소득원이 되고 있다 . 물레고둥의 어획에사용되는 통발의 형태는 반구형 또는 원통형이다(NFRDI , 2008 ; P1B; 5D 1< ., 2007).어업생산통계 (8DD@ :// 6C .69@C .7? .;B ) 자료에 의하면 우리나라 고둥류의 연간 어획량은 6,000 ∼7,000 M/T이며 어획량의 약60% 가통발에 의해 어획되고 있다 . 우리나라동해안에서 어획되는 물레고둥의 어획량 변동에 관한정확한 통계 자료는 없으나 , 소형 개체의 보호 , 가격 안정등의 지속적 이용 방안을 강구하기 위한 노력이 필요하다 .일반적으로 어구와 조우하는 대상 생물의 크기는 다

Mesh selectivity of drum net traps for Buccinum opisoplectum Dall using SELECT model with unequal fishing and sampling efforts: A preliminary analysis

The mesh selectivity of drum net traps for Buccinum opisoplectum Dall caught in the eastern sea of Korea was described. Several experiments were conducted between July 2003 and March 2004 and the data obtained from the experiment was fitted by SELECT (Share Each Length class`s Catch Total) model with unequal fishing and sampling efforts. The selection curve was determined to be `estimated fishing efficiency` by model deviance rather than AIC. However the fishing efficiency between 20mm and 35mm mesh size did not seem to be different. The lengths of the selectivity for the 55mm and 75mm mesh size were 65.4mm and 96.0mm, respectively.

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

Backscattering Strength and Vertical Distribution of dominant fishes in inland waters by Hydroacoustics

This study is aimed to understand the vertical distribution of fish in the daytime and nighttime using an acoustic survey in Yondam reservoir of Jeollabuk-do, and an acoustical backscattering strength of dominant species, bass (Micropterus salmoides) and a bluegill (Lepomis macrochirus), which are classified as the ecosystem disturbing species. The results showed that the fish school was distributed in the shallow areas of less than 10 m depth during the period of Aug. and Oct. where it had a strong thermocline, otherwise, it was distributed over 10-times density under stable water temperatures as 13℃ in Nov. There was no vertical patchiness difference between daytime and nighttime unlike the typical marine ecosystem. The dominant species were crucian carp, bluegill, bass. The hydroacoustic method can provide the spatial distribution and effective removal ways of the ecosystem disturbing species in inland fisheries.