• 한국어병학회지
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• 제22권2호
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• pp.163-166
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• 2009

The ectoparasite ciliate Trichodina has been recorded from above 100 species of freshwater and marine fishes. In April 2009, we investigated the trichodia infection in 13 species of marine fishes captured by emplacement net and gill net in order to understand trichodina infection status among the natural fish populations along the Namhae-Gun coast area, the southen coast of Korea. Trichodina infection was observed in 10 out of 10 sea basses Lateolabrax japonicus, 2 out of 5 finespotted flounder Pleuronichthys cornutus and 1 out of a stone flounder Kareius bicoloratus. The sea bass infected with the parasite showed hypertrophy and exfoliation in gill epithelium. In addition, hyperplasia and lamellar fusion of gill filament were noticed among naturally affected sea bass.

• Fisheries and Aquatic Sciences
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• 제5권2호
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• pp.141-143
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• 2002

The treatment efficacy of oral administration of praziquantel against the blood-sucking monogenean Microcotyle sebastis under the commercial rockfish-culture conditions was evaluated. The quantity of praziquantel added to the food was calculated so that the amount of praziquantel ingested daily by fish was 200mg or 400mg/kg body weight (bw). The fish were fed a moist-pelleted fish meal supplemented with praziquantel at an rate of 0 (control), 200 or 400 mg of praziquantel per kg bw, respectively, for 3 times at an interval of 24 h. On 1 day to 8 days after the treatment, 10 fish were taken randomly from each net-pen daily (80 fish in each group in total), and the efficacy of each treatment was confirmed. Abundance of worms were significantly reduced in groups fed praziquantel-supplemented diets. The results clearly demonstrated that feeding the praziquantel-supplemented diet was effective for controlling M. sebastis infestation in practical commercial rockfish-culture systems without imposing any handling stress.

• 한국수산과학회지
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• 제12권4호
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• pp.217-224
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• 1979

조업중의 어선이나 어구로부터 발생되는 수중소음의 음향특성을 구하기 위하여 특별히 고안된 수중녹음장치를 이용하여 트로올어구의 수중소음을 녹음분석한 결과는 다음과 같다. 1. 조업중인 트로올어구에서 측정수 소음에는 어선이 발하는 소음의 영향을 극히 적다. 2. 소음의 주파수분포는 $DC\~6,300\;Hz$이고 그 중 우세한 주파수대는 $100Hz\~6,300Hz$이며 최대음압은 $137db(re\;1:{\mu}Pa$이었다. 3. 뜸줄부보다 발줄부에서 음압준위가 높고 자루부분에서의 음압준위가 가장 낮았다. 4. 예망중일 때보다 양망중일 때가 음압준위가 높고 투망중의 음압준위가 가장 낮았다. 5. 예망중의 트롤어구에서 발생되는 수중소음의 주된 음원은 어구의 ground rope와 해저의 마찰음 및 otter board와 해저와의 마찰음이라고 추정할 수 있다.

• 한국수산과학회지
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• 제47권6호
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• pp.997-1005
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• 2014

We analyzed annual and seasonal variations in fish species composition and distribution patterns using both daily catch and quantitative analysis data collected from a set-net fishery over a period of two years (2011-2012) on the coast of Dapo, Geoje Island. Set-net fishing season in this area is from May to November, and the annual yield based on the daily catch data was 171,412 kg in 2011, and 102,611 kg in 2012. In total, there were 46 species (belonging to 36 families and 12 orders) in 2011, and 41 species (belonging to 25 families and 9 orders) in 2012. The dominant species in terms of numbers were Trachurus japonicus, Engraulis japonicus, Clupea pallasii, Scomber japonicus, and Sphyraena pinguis. The range in fork length for T. japonicus and E. japonicus was from 3.2 to 23.9 cm, and from 2.6 to 13.3 cm, respectively. The fork length of recruiting juveniles to the Dapo set-net fishing ground ranged from 4.6 to 7.8 cm (median) for T. japonicus, and from 4.1 to 5.0 cm (median) for E. japonicus. The fact that most of the fish caught from the two species were at immature growth stages implies that the coast of Dapo can act as a nursery area for these migratory species.

• Fisheries and Aquatic Sciences
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• 제18권3호
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• pp.283-286
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• 2015

This is the first report of Pterygotrigla multiocellata from the family Triglidae, collected in Korea. The specimen (314 mm in standard length) was caught in a gill net in the coastal waters of Jeju Island on 11 February 2010. This species is characterized by the following morphological traits: head large and triangular, bony plates absent along the base of the second dorsal fin, antrorse rostral spine long, and cleithral spine long. We suggest a new Korean name, "Gin-ppul-mit-seong-dae" for P. multiocellata.

• 한국수산과학회지
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• 제1권2호
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• pp.129-133
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• 1968

The writer reviewed the cutting method of webbing practiced in major countries. Cutting rhythm Bar cutting to Point Cutting) should be chosen to approach as straight as possible, therefore the knot cuttings or the side cuttings should be 1, if possile. According to calculation, an arbitrary solution to a mixed cutting was undertaken, while another cutting method, of calculation 5 and 6, was taken by a prepared table. In no case, it was consequently possible to use an unmixed cutting rhythm. Sometimes, the cutting calculated from approximate value differs from desired result, tut this defference should not be taken too significant in practice.

• 한국양식학회지
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• 제16권3호
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• pp.171-178
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• 2003

Inorganic nutrients such as nitrogen and phosphate compounds accumulate in recirculating aquaculture systems. These nutrients must be removed from the system before they affect pH and fish health. For this purpose, aquatic plants are a simple and inexpensive method of removal. There are four commonly used aquatic plants: Eichhornia crassipes (water hyacinth), Pistia stratiotes (water lettuce), Hygrophila angustifolia, and Hydrocotyle leucocephala in freshwater recirculating aquaculture systems in Korea, but their efficiencies are not known. Therefore, removal efficiencies of inorganic nutrients from a freshwater recirculating aquaculture water with four commonly used aquatic plants were tested. Removing efficiencies of TAN, N $O_2$$^{[-10]}$ -N, and N $O_3$$^{[-10]}$ -N of the plants in 210 L aquaria for 48-hour period were tested. The removing efficiencies of TAN, N $O_3$$^{[-10]}$ -N, and P $O_4$$^{3-}$-P of the two most effective plants, water hyacinth and water lettuce, were also tested in 690 L (surface area of 1.55 $m^2$) tanks under 2 different initial stocking densities, 4 kg and 6 kg, for 22 days. Proximate analysis major nutrients and N and P contents of the all plants were analyzed for calculating net removal weight of N and P by the plants. Water lettuce was the most effective for removing TAN, N $O_2$$^{[-10]}$ -N, and N $O_3$$^{[-10]}$ -N from the water for 48-hour period tested followed by water hyacinth and Hygrophila angustifolia. Water lettuce reduced TAN, N $O_2$$^{[-10]}$ -N, and N $O_3$$^{[-10]}$ -N concentration from 2.3 mg/L, 0.197 mg/L, and 21.4 mg/L to 0.4 mg/L, 0.024 mg/L and 17.4 mg/L, respectively while water hyacinth reduced them down to 0.6 mg/L, 0.029 mg/L and 17.9 mg/L, respectively. The concentrations of TAN, N $O_2$$^{[-10]}$ -N, and N $O_3$$^{[-10]}$ -N in Hydrocotyle leucocephala group were rather increased up to 3.7 mg/L, 5.7 mg/L and 48.2 mg/L, respectively. This is because the creeping stem of Hydrocotyle leucocephala had to be cut to meet stocking weight resulting in decaying of the stem in the aquaria during experiment. The net growth in weight of water hycinth and water lettuce of 4 kg each in the 1.55 $m^2$ tanks for 22 days were 9.768 kg and 10.803 kg respectively, and those at initial weight of 6 kg each were 8.393 kg and 9.433 kg, respectively. The reason of lower net growth in the later group was restricted growth space. Nitrogen and phosphorus contents in water hyacinth were 2.89% and 0.27%, and those in water lettuce were 3.87% and 0.36%, respectively. Average quantities of removed N and P from 1.55 $m^2$ tanks by water hyacinth for 22 days were 18.9 g and 1.75 g, while those by water lettuce were 36.8 g and 3.5 g, respectively. Therefore water lettuce showed much higher efficiencies for removing both N and P from recirculating aquaculture water than water hyacinth.

• 한국수산과학회지
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• 제47권6호
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• pp.1037-1054
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• 2014

In this study, the status of coastal fisheries was examined based on the catch and number of fishing vessels of coastal fisheries in Korea. Comparing the status on coastal fisheries of the East Sea, Yellow Sea and South Sea in Korea, scientific evidence was made for fisheries management on coastal fisheries based on characteristics of each sea area. From 1990 to 2011, the catch of coastal fisheries in Korean waters ranged from 150,000 mt to 230,000 mt, with an average of 190,000 mt, and it accounted for 15% in average of total catch fished in adjacent waters of Korea. In order of catch by coastal fisheries, gillnet (36.7%) was the primary fishery, followed by coastal complex (24.7%), stow net (18.3%), trap (12.9%), lift net (3.9%), purse seine (3.0%) and beam trawl (0.4%) fisheries. In order of catch by species, anchovy (15.0%) had the largest proportion of total catch, followed by common squid (10.3%), akiami paste shrimp (5.2%), blue crab (3.9%) and octopus (3.7%). Of the average catch by sea area from 1990 to 2011, Yellow Sea, South Sea and East Sea were 37.4%, 34.6% and 28.0%, respectively. Since 2000s, however, the average catch of South Sea has accounted for the largest proportion. The number of permitted fishing vessels involved in 8 coastal fisheries was 55,336 vessels in average from 1997 to 2011. The number of vessels was about 47,000 vessels in 1997, and increased to 61,300 vessels until 2000, then has decreased to 44,000 vessels operating in 2011. In order of the number of permitted fishing vessels by fisheries, complex (52.4%) took the first place, followed by gillnet (31.5%), trap (13.4%), stow net (0.8%), beam trawl (0.8%), purse seine (0.6%), lift net (0.4%) and seine net (0.0%). In order of the number of permitted fishing vessels by sea area, South Sea (29,994 vessels) took the first place, followed by Yellow Sea (18,185 vessels) and East Sea (7,158 vessels). In order of the catch per unit effort (CPUE, mt/vessels) which was analyzed using catch and number of vessels in average by fishery, stow net is the highest followed by lift net, trap, purse seine, gill net, beam trawl and complex fisheries. In particular, the CPUE of complex and gill net fisheries, which accounted for the largest number of vessels were 4.0 mt/vessels and 1.6 mt/vessels, respectively. Since those are too low relative to other fisheries, it was judged to need systematical management on both fisheries.

• 한국수산과학회지
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• 제41권4호
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• pp.272-281
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• 2008

Seasonal and annual variation in the species composition of bag-net catch in the coastal waters of Incheon, Korea were examined from April 2000 to November 2004. To analyze seasonal variation of the fisheries data, we implemented a self-organizing map(SOM), an unsupervised artificial neural network, with the catch amount of 97 species. Over 5 years, we caught 68 species of fish, 23 species of crustaceans and six species of cephalopods. The total number of fish species were gradually increased during the study period. The number of species was higher during the spring than the autumn. The SOM identified four groups of the sampling months based on seasonal changes in communities. In the spring, the dominant species were Leptochela gracilis and Pholis fangi; whereas, in the autumn, Engraulis japonicus and Portunus trituberculatus were dominant species in bag-net catch. Our results will be used to estimate seasonal and annual variation in fisheries resources of Korean coastal waters.

• 한국수산과학회지
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• 제30권1호
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• pp.105-113
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• 1997

흥해 연안에서 1989년 5월에서 1990년 10월 사이 삼중자망으로 어류를 채집하여 채집시기에 따른 종조성을 파악하고, 우점종의 체장 분석을 통하여 망목에 따른 어종별 체장 선택성을 분석하였다. 총 28종의 어류가 채집되었으며, 개체수와 생물량은 뚜렷한 계절 변화를 보이지 않았다. 겨울에서 여름 사이에는 주거종인 볼락, 노래미 및 쥐노래미가 우점하였고, 가을에는 회유종인 쥐치와 말쥐치가 우점하였으며 주거종의 수는 감소하였다. 자망 100m 당 12시간 평균 어획량은 11마리, 1,938 g이었으며, 채집된 주어종들은 3세 이상의 체장 20cm 이상의 개체가 주를 이루었다.