Thousands of pelagic and demersal fishes inhabit the waters around Korea and many of them are overexploited. One of the reasons is technological development, which increases the efficiency of the vessels continuously. The analysis was conducted to identify the change of fishing power index to develop the vessel and gear technology that may have improved the fishing efficiency of the otter trawl fishery from 1960s to 2010s. Gross tonnage was decreased stably, but horse power was increased annually. The perimeter of net mouth was somewhat longer, but little changed. Color fish finder was utilized from the mid-1960s. Hydraulic net drum were introduced in the early 1990s, and supply rate was gradually increased. Surveys on the supply and upgrading of fishing equipment utilized visiting research. Therefore, the relative fishing power index in the trawl fishery increased about two to three times in the 2010s compared to the 1980s. The results are expected to contribute to reasonable fisheries stock management.

The species composition and abundance variations of fishery resources in the adjacent marine ranching area, Tongyeong, Korea, were investigated by shrimp trawl, gill net, and longline during the period of July, September, and October in 2016. During the study period, the total catch were 8,522.9 kg with 34 species from the shrimp trawl, 32 species from the gill net, and nine species from the longline. The dominant species were different by gear, which were Hypodytes rubripinnis and Parapercis sexfasciata in the shrimp trawl, Platycephalus indicus and Raja kenojei in the gill net, and Conger myriaster and Scomber Japonicus in the longline. In terms of spatial distribution, Yongchodo showed the highest total catch in number as well as of in weight while Jukdo showed the lowest total catch in number and Bijindo showed the lowest total catch in weight. The amount of demersal fish resources in the survey area estimated as 301 ha, was 99,396 individuals which was converted to be 8,552.9 kg. The amount of demersal fish resources by gear were of trawling area, which area is 127 ha, were 76,251 and 3,489.5 kg, 74 ha in the gill net and longline survey area was 16,213 and 3,457.3 kg, and the other 100 ha area was 6,932 and 1,606.1 kg. In this study, the minimum resources for demersal fish is 61,687 and 4,265.2 kg, and the maximum is 149,439 and 14,197.9 kg.

A study for species composition and abundance of the fish assemblages in the coastal Sacheon Bay, Korea were conducted using monthly collection by a shrimp beam trawl from March 2015 to February 2016. The number of individuals, biomass and species diversity indices fluctuated with the station and month. Of all 73 species collected, the dominant species in terms of numbers were Liparis tanakae, Zoarces gillii, Amblychaeturichthys hexanema, Ricuzenius pinetorum and Pleuronichys cornutus. The peak number of fishes occurred in March and April, whereas the biomass of fishes was highest in April. The numbers and biomass of fishes were lower in February corresponding with the low temperature, and diversity indices were highest in June. Due to those seasonal difference in abundance of the dominant species, fish community were divided into three main groups. In addition, seasonal difference by station of fish community were devided into four main groups. Juvenile fishes of coastal Sacheon were presented during the study period. It presented that the study area served as an important role in spawning and nursery ground for fisheries resource.

This study attempted to help determine Korean fishery policies by proposing improvement plans after examining the current regulations, fishing vessels, fishing gear and fishing methods of the middle sized trawl fishery in the East Sea for targeting only squid. In general, the size, engine horse power, and net length of the middle sized trawlers are between 50 and 60 GT, 1,200 and 1,600 PS, and approximately 165 m with four seamed trawl nets, respectively. While a jigging vessel attracted squids using lights, the trawler approached a jigging vessel. The trawler let the jigging vessel know its decision for fishing, and then jigging vessel rolled up jigs. The net of the trawler was casted at 45 degrees between the bow and the stern of the jigging vessel. Once the trawler towed close to the stern of the jigging vessel upon its passing of the jigging vessel, the bow of the trawler turned 45 degrees left again. Then, squid aggregations were entered into the net. When the cod end was passed a light vessel, the trawler hoisted the net up to the otter board. Then the trawler turned 180 degrees. It repeated three to five times of fishing operations as the previous method. We recommend that the regulations allow nineteen side trawlers to catch like stern trawler, as well as the cooperative trawler and jigging vessel operations.

Annual and monthly pollock catches, CPUE and fishing grounds in the high seas of Bering Sea between 1984 and 1992 were analyzed for centroid distribution and bivariate ellipses of trawlers of South Korea, Japan, Poland and China. The catch amount differed by country as 56.1%, 21.7%, 20.4% and 1.8% were caught by Japan, Korea, Poland and China respectively. Japan recorded the highest mean CPUE at 5.7 ton/hour while it was 4.3 ton/hour for Poland, 3.9 ton/hour for Korea and 2.4 ton/hour for China. Cumulative catch varied by month, with the minimum of 137,000 ton in March and the maximum of 848,000 ton in December. Monthly mean of CPUE was the lowest in February (2.0 ton/hour) and the highest in November (6.3 ton/hour). The centroid distribution of monthly fishing ground was located at a southern spot (56° 05'N, 178° 55'E) in January, and it moved anti-clockwise toward 56° 37'N, 178° 24'E in December. Fishing grounds were scattered more by the east-west direction than by the south-north direction. The fishing grounds were similar for Korean, Japanese and Polish trawlers, but Chinese trawlers that fished only from July to December showed distinctively different fishing grounds from the others.

The study aims at a selective effect of the Grid and Window net in the shrimp beam trawl.The experimental trawling of the Proto type, Grid type and Grid and Window net type was performed in a sea area of Geo–je and Tong–yeong from Mar, 2006 to Apr, 2010. The obtained results are as follows; Catch per unit area (Number) of the Proto type net and Grid type net were 0.18/m2, 0.23/m2, respectively. The Grid type demonstrated 2.4% lower bycatch rate than the proto type (6.6% vs 4.2%, respectively). In addition, in terms of total weight, the bycatch rate of Grid type was 7.6% lower than the proto type (50.2% vs 42.6%, respectively). In the comparison of shrimp catch, the Proto type demonstrated better haul outcome (0.02 case/m2) than the Grid & Window type (0.02 case/m2). The Grid & Window net type demonstrated 16.4% lower bycatch rate than the Proto type (32.2% vs 48.6%, respectively). In addition, in terms of total weight, the bycatch rate of Grid & Window net type was 8.3% lower than the Proto type (85.9% vs 94.2% respectively).

The aims of this study are to access the status and problems and draft possible solutions of Korean trawl fishery in New Zealand sea. The main target fish species for Korean trawlers in this sea were barracouta, blue mackerel, hake, hoki, jack mackerel, ling, oreo, orange roughy, southern blue whiting, spiny dogfish, squid and silver warehou. The Korean trawl fishery are suffering from a supply of seaman, continuous increasing coast of the counter partner, repair of vessel and seaman supply. It may be useful for getting over these difficulties to build a new trawler with a automatic operation system.

본 연구에서는 충남 연안에서 연안조망의 어획 특성을 파악하기 위하여, 2008년 3월부터 2009년 2월까지 매월 2∼4회 연안조망을 사용하여 어획조사를 실시하였다. 조사 해역은 동경 125도 50분∼126도 05분, 북위 36도 15분∼36도 25분의 해역이었고, 총 19목 63과 96종이 채집되었다. 그 중 어류가 54종, 갑각류가 27종, 복족류 및 이매패류가 9종, 그리고 두족류가 6종이었다. 생체량은 어류가 51.4 %로 가장 많았으며, 갑각류는 34.2 %를 차지하였다. 꽃새우는 7월~11월에 출현량이 많았고, 12월부터 5월까지는 적은 양이 출현하였다. 연안조망의 목표종인 꽃새우는 전체 어획물의 2.1 %로 낮은 채집 비율로 출현하였으며, 꽃새우 이외 어종의 부수적 어획물의 양적 비율이 높아, 꽃새우 어획이 부수어획으로 어획되는 종들의 수산자원에 미치는 영향이 클 것으로 판단된다.

Experimental fishing operation by the shrimp beam trawl was carried out to investigate the bycatch in order to develop the selective fishing gear of the shrimp beam trawl fishery. The experimental trawling was performed by the prototype fishing gear in coast sea of Boryeong, Buan, Kangjin, Tongyeong and Geoje from 30 April to 13 November 2005. Bycatches of the experimental trawling were analyzed species composition, total length composition. The results obtained can be summarized as follows; Target fishes caught by the shrimp beam trawl were Palaemon gravieri, Crangon Hakodatei, Trachysalambria curvirostris, Parapenaeopsis tenellus, Rhynchocinetes uritai and Matapenaeus joyneri. And their fishing rate and total length range were 50.0%, 46.0%, 2.6%, 0.4%, 0.3%, 0.3% and 40-80mm, 40-80mm, 120-150mm, 60-80mm, 60-80mm, 60-120mm respectively. Bycatches caught by the shrimp beam trawl consisted of fishes of 30 kinds, 6 kinds of mollusk, 5 kinds of shellfishes and 3 kinds of crabs. The main fish was Engraulis japonicus, Platycephalus indicus, Paralichthys olivaceus, Leiognathus nuchalis and Conger myriaster, their occupied rate were 47.0%, 16.6%, 13.6%, 5.5%, 2.7% respectively, and their total length range were 60-150mm, 80-410mm, 80-600mm, 30-80mm and 150-460mm respectively. A number bycatch rates of shrimp beam trawl fishery were 99.7% in Buan, 60.0% in Kangjin, 14.6% in Boryeong, 10.6% in Tongyeong and 2.7% in Geoje, The weight bycatch rate were 99.9% in Buan, 75.1% in Kangjin, 57.1% in Tongyeong, 47.4% in Boryeong and 15.4% in Geoje.

동해구 트롤 어구어법을 개발하기 위하여 생력화 조업시스템을 개발하고, 생산성을 높이는 선택형 개량어구를 개발하는데 연구목표를 두었다. 생력화 조업시스템으로 폭 2.0m 1.8m인 네트드럼을 제작하고, 현용 와이어드럼에 와이어리더를 설비하여 생력화를 도모하였고, 선미에 겔로스를 설비하였다. 그 결과, 투양망시에 인력에 의한 그물을 들어올리거나 적재하는 일이 조업시스템으로 대체되어 선원들의 노동력은 기존의 것에 비하여 80% 정도 낮게 개선되었다. 또한, 중\ulcorner저층 겸용어구 A형과 저층용어구 B형을 개발하고, 단일 슬롯 V-만곡형 전개판을 설계\ulcorner제작하고, 네트레코더를 설치하여 1999년 9월말부터 2000년 5월까지 시험조업한 결과를 요약하면 다음과 같다. 1. A형의 망고는 중층예망시 약 30-35 m이나 저층예망에서는 19-20 m이며, 망폭은 29-31 m 정도로 추정되었으며, 저층예망시 전개판의 수중위치는 해저에서 10 m 정도 위쪽에 위치하고 있는 것이 확인되었다. 2. A형의 저층예망시의 기관 부하는 어구의 유체저항이 커서 재래식에서 보다 10rpm 정도가 더 요구되었다. 3. A형의 어획성능은 4시간 정도 예망하였을 때 분홍새우의 어획량이 재래식 어구에 비하여 약 3배정도가 더 많았고, 선택성이 매우 강한 특성을 보였다. 4. A형 어구에 의하여 어획된 분홍새우는 상품성이 우수하여 타선의 것보다 상자당 3,000-7,000원 정도 고가로 위판되었으며, 동급의 기존 트롤선에 비하여 생산성이 약 30%정도 향상된 것으로 나타났다. 5. A형 어구에 의한 조업에서는 펄을 뜨는 일은 전혀 없으며, 재래식 그물에서 대량으로 올라오는 불가사리나 기타 쓰레기 등이 거의 입망되지 않으므로, 어획물의 처리과정이 용이하여 선원의 노동력도 크게 절감할 수 있었다. 6. 천장망 길이가 약 23 m인 B형은 망고가 약 10 m, 망폭이 약 33m로 각각 추정되었으며, 예망시의 기관 부하도 예망속도 2.5노트까지는 큰 무리 없이 조업이 가능하였다. 7. B형의 어획성능은 새우의 어획량이 재래식 어구를 사용하는 어선에 비하여 5배 이상으로 나타났고, 청어는 약 2배정도 많은 것으로 확인되었으며, 기타 어류의 어획도 약 2배가 많았으나, 고등류, 문어류, 그리고 게류의 어획은 거의 없어서 선택성이 큰 것으로 나타났다. 8. B형의 생산량과 생산액은 재래식에 비하여 약 1.1배와 1.7배로 크게 나타나서 어업의 생산성이 크게 개선되었다. 동해구트롤어업의 합리적인 운용을 위하여 청어, 가자미, 게, 오징어 등의 어종을 효율적으로 어획할 수 있도록 어구의 기능을 확대하여야 할 것이고, 조업에 막대한 지장을 주고 있는 해파리의 탈출을 위한 그리드(grid)의 적용이 필요하다. 나아가 이 개량어구의 보급이 확산되면 분홍새우의 남획은 피할 수 없을 것이므로 합리적인 어획을 위한 자원관리방안이 확립되어야 할 것으로 보아진다.