• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.3
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• pp.43-52
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• 2005

Evaluations of the fish farm influences on stream water quality may provide basic informations on watershed management to reduce environmental impact due to fish farm development and to conserve stream water quality in forested watershed area. In this research influent, effluent water in the fish farm and stream water qualities around Mt. Baegun area were monitored seasonally for six years and the following results were obtained. Due to the increase of pH in effluent water from the fish farm it was believed that alkalization of stream water can be accelerated by large scale development of fish farms in the forested watershed area. Also, effluent water from the fish farm increase of EC higher than influent and stream water. As a result of regression analyses, pH, EC, DO, water temperature, total amount of cation and anion in influent and effluent water of fish farm show high significance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.13 no.2
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• pp.27-32
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• 1977

The paper deals the fishing condition of the stern trawlers operated in the Atlantic coast of Africa. The datas are gathered from the Korean stern trawlers operated in the area from June, 1975 to May, 1976. The obtained results are summarized as follows: 1. The mean catch per haul are calculated as, cuttle fish 14.5kg, large size squid(more than :lOOg of body weight) 28.2kg, small size squid(less than 300g) 36.4kg, octopus 47.0kg. 2. Small size cuttle fish(less than5OOg of body weight) are caught much during after spring tide in July to September, yet, large size ClIttle fish(more than 500g) are caught much during neap tide in October to January. 3. Small size squid(less than 300g of body weight) are cBught much during after spring tide in October to December, yet, large size squid(more than 3OOg) are caught much during before spring tide in October to March. 4. Octopus are caught during neap tide in July to August.

• Journal of Aquaculture
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• v.18 no.3
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• pp.154-159
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• 2005

This study was conducted to evaluate the effects of size grading on growth, feed efficiency and survival of juvenile olive flounder. Juvenile flounder were divided into four groups by initial average size; Small group $(1.3{\pm}0.23g)$, medium group $(3.1{\pm}0.45g)$, large group $(4.9{\pm}0.57g)$ and ungraded group $(3.3{\pm}1.66g)$. Triplicate groups of 100 fish were reared over 8 weeks. In final body weight distribution, frequency of the small size flounder (10 g) was markedly higher in the ungraded group than in the small group. Specific growth rate, feed efficiency and survival in the ungraded group were significantly lower (P<0.05) than those in the pooled data of the othor three graded groups, although feed intake in the ungraded group was significantly higher (P<0.05) than that of the pooled data of the other three graded groups. These results show that the small flounder gained significantly faster growth and higher survival in the absence of the large flounder. Therefore, size grading seems to be an important and necessary operation to improve the growth and survival of juvenile olive flounder (1-5 g).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.6-12
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• 1998

The moving behaviour of Yellowtail Seriola quinqueradiata schools in the main-net of a large scale set-net was investigated in relation to the catching function of the funnel-net by a scanning sonar. The investigation was took place in the Kishihata set-net fishing ground located in Nanao city Ishigawa prefecture, Japan from Nov. 9 to Nov. 13, 1992. The obtained results are summarized as follows; 1. Fish schools showed the greatest number at the playground in the morning and at the bag-net in the afternoon. The fish schools remained long time in the main-net. 2. The rate of fish school through the funnel-net was smaller than that of fish school which is though the playground and bag-net. Because the Yellowtail school changed the shape of school in passing the funnel-net. 3. The rate of entering the bag-net was 24%, among the fish school heading to the outer funnel-net. But, the rate of escaping to the playground was 27%, among the fish school heading to the inner funnel-net. It seems that the structure of the outer funnel-net was not enough to lead the fish to the bag-net. However, the structure of the inner funnel-net was very effective at preventing escape. 4. It is appropriate to haul the net in the morning in considering the number of accumulated fish in the bag-net during the survey.

• Journal of Aquaculture
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• v.7 no.3
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• pp.165-175
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• 1994

Attempts were made to find out nitrogen and phosphorus loads to aquatic environment resulting from feeding Nile tilapia (Oreochromis niloticus). Two different size groups, small and large, were used. The average sizes of small and large tilapia were 65.2 g and 389.2 g respectively, and three kinds of commercial diets were used for each size. The 3 kinds of commercial diets for tilapia contained in average 33.8% crude protein ($5.4\%$ nitrogen) and $1.4\%$ total phosphorus. The load of nitrogen and phosphorus were measured by subtracting the amounts of nutrients retained in the body of fish from consumed nutrients. Sixty, five percentage of total feces was excreted within 24 hours after feeding at $23^{\circ}C$. Nitrogen content in the feces was higher in large fish than small ones. The apparent digestibility of dietary protein for small and large tilapia was $90.0\%$ and $89.7\%$, respectively. Availability of dietary phosphorus for small and large tilapia was $44.7\%\;and\;51.4\%$, respectively. The total load of nitrogen and phosphorus per 1 metric ton of tilapia production was 49.5kg and 6.3kg, respectively, for small ones with feed conversion ratio (FCR) of 1.4, and 61.3 kg and 13.4kg, respectively, for large ones with the FCR of 1.8. Nitorgen balance appeared that small and large tilapia excreted $7.1\%\;and\;9.9\%$ of consumed nitrogen through fecal-nitrogen and $55.5\%\;and\;62.3\%$ through urine and gills, retaining $37.4\%\;and\;27.8\%$ in the body, respectively. These results show that small fish pollute less than large fish, excreting less and retaining more nutrients in the body.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.173-174
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• 2003

Dietary proteins are the most important factors affecting growth performance of fish and feed cost. Generally, most of the formulated diets for marine fish include a large amount of fish meal as a protein source because of its high nutritive value and palatability. Quality of fish meal in diet may affect on growth and feed efficiency of fish. Therefore, this study was conducted to evaluate the effect of various fish meals as dietary protein source on growth and feed utilization of the juvenile flounder. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.638-644
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• 2022

The measurement of morphological features is essential in aquaculture, fish industry and the management of fishery resources. The measurement of fish requires a large investment of manpower and time. To save time and labor for fish measurement, automated and reliable measurement methods have been developed. Automation was achieved by applying computer vision and machine learning techniques. Recently, machine learning methods based on deep learning have been used for most automatic fish measurement studies. Here, we review the current status of automatic fish measurement with traditional computer vision methods and deep learning-based methods.

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.8-18
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• 2005

A total of 33 fish species were collected by a small beam trawl from an eelgrass bed in Myoungjuri of Jindong Bay, Korea. The dominant fish species were Hexagrammos otakii, Pholis fangi, Repomucenus valenciennei, Pseudoblennus cottoides, Pholis nebulosa, Rudarius ercodes, Syngnathus schlegeli, and Sebastes schlegeli. These 8 fish species accounted for 79.5% of the total number of individuals collected. The fishes collected in the study area were primarily small fish species or juveniles of large fish species. Seasonal variations in both species composition and abundance were large; higher numbers of fish occurred from April to June 2002, while biomass was the highest in September 2001 and 2002. Seasonal changes in fish abundance corresponded with eelgrass biomass and abundance of food organisms.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.358-365
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• 2000

To evaluate the influences of stocking and removal of silver carp on plankton communities and physicochemical parameters, fish biomanipulation was conducted in six enclosures constructed on the coast of a hypertrophic lake during the summer of 1997. Of these, three enclosures were established for the fish-stocking experiment; one fishless enclosure used as a control and two enclosures with high and low densities of fish. The other three enclosures for the fish-removal experiment were prepared in an entirely converse process compared to that for fish stocking. The results of randomized intervention analysis (${\alpha}=0.05$) showed significant changes in several physicochemical parameters and plankton communities after fish stocking and removal. Fish stocking decreased water transparency, DO, pH and chi-a (> $40\;{\mu}m$), while increasing the concentration of nitrogen and chi-a (<$2\;{\mu}m$). However, water transparency did not increase by fish removal. Small plankton communities, such as picocyanobacteria, eukaryotic picoplankton and ciliates (<$2\;{\mu}m$) showed significant reciprocal changes after both fish treatments: increase by the presence of fish and decrease by the absence of fish. No count of large sized phytoplankton and zooplankton showed significant change in the presence of fish, while large zooplankton, Diaphanosoma, Cyclopida and nauplii were significantly increased by fish removal. Although the frequent heavy-winds and endless supply of phosphorus from the lake sediment strongly disturbed the fish behavior and enclosure management, the stocking and removal of silver carp showed an obvious reciprocal influences on plankton communities and its physico-chemical parameters in a shallow-hypertrophic lake.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.13-20
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• 1998

The moving behaviour of Yellowtail Seriola quinqueradiata schools in the main-net of a large scale set-net was investigated in relation to the catching function of the funnel-net by a scanning sonar. The investigation was took place in the Kishihata set-net fishing ground located in Nanao city Ishigawa prefecture, Japan from Nov. 9 to Nov. 13, 1992. The obtained results are summarized as follows; 1. Fish schools showed the greatest number at the playground in the morning and at the bag-net in the afternoon. The fish schools remained long time in the main-net. 2. The rate of fish school through the funnel-net was smaller than that of fish school which is though the playground and bag-net. Because the Yellowtail school changed the shape of school in passing the funnel-net. 3. The rate of entering the bag-net was 24%, among the fish school heading to the outer funnel-net. But, the rate of escaping to the playground was 27%, among the fish school heading to the inner funnel-net. It seems that the structure of the outer funnel-net was not enough to lead the fish to the bag-net. However, the structure of the inner funnel-net was very effective at preventing escape. 4. It is appropriate to haul the net in the morning in considering the number of accumulated fish in the bag-net during the survey.