• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.259-266
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• 2011

To produce cupped oyster sprat consistently, we investigated the efficiency of nine settlement substrates using selective breeding of Pacific oyster Crassostrea gigas, with the goal of popularizing off-bottom culture on the west coast of Korea. We also compared the growth and survival of selectively bred sprat (diploid) with triploid sprat from an off-bottom culture system. Considering, the attachment rate and detachment efficiency, producing cupped oyster in a polypropylene gunny bag proved to be the most effective method. There were no differences in shell growth or total weight between the diploids from selective breeding and triploids from off-bottom culture for 5 months. However, the survival rate was 8 times higher in the diploids than the triploids. Transplanting sprat from selective breeding is one way to restore oyster farms and nurture off-bottom culture along the west coast.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.818-823
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• 2017

The diet composition of juvenile gold-eye rockfish, Sebastes thompsoni (40-50 mm SL), was examined based on 121 individuals collected in the Yellow Sea Bottom Cold Water in August 2016. The Yellow Sea Bottom Cold Water is characterized a by water mass of <$10.0^{\circ}C$ and 33 psu. The juvenile gold-eye rockfish fed on Amphipods [57.3% index of relative importance (IRI)] and Euphausiacea (32.9%). Most of the point in the prey-specific abundance plot indicated a high between-phenotype component (BPC).

• Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.337-343
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• 2012

The Korean bottom trawl survey was conducted using a trawl designed by the National Fisheries Research and Development Institute (NFRDI). The capture efficiency and size selectivity of this trawl for snow crab Chionoecetes opilio was investigated by experimental tows. An auxiliary sampling net (underbag) was attached beneath the trawl net to capture crabs escaping under the trawl footrope. Experimental tows were made by the same vessel speed (3.4 knots) as in the bottom trawl survey, but toing time was shortened from the standard 30 min to 10 min to reduce possible trawl distortion due to the high catch rate of mud and debris in the underbag. In averaged over 17 tows conducted between 110-383 m depth, trawl efficiency of both males and females combined increased from about 10% at 20 mm (carapace width) to about 70% at 100 mm, with a width of 50% capture equal to 78 mm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.4
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• pp.397-409
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• 2024

To evaluate the recent trophic state of Jinhae Bay, field campaigns were conducted in June and August during 2020-2023, measuring environmental factors in both the surface and bottom layers. Temperature differences between layers were greater in August than in June. Surface salinity was decreased in August, probably due to runoff, while bottom salinity remained stable. Dissolved oxygen levels showed a more pronounced stratification in August, leading to hypoxic conditions in the bottom layer. Chemical oxygen demand (COD) was higher at the surface, with rainfall contributing to elevated levels. The eutrophication index (EI) was consistently higher at the bottom across all stations, driven by dissolved inorganic nitrogen (DIN) and phosphate (DIP), with a notable increase in August due to organic matter decomposition. The trophic index (TRIX) was also higher in the bottom layer, with surface TRIX influenced by DIN and salinity, and bottom TRIX by salinity, rainfall, COD, and DIN. The average TRIX for Jinhae Bay was 4.21±1.30, classified as "poor", but comparable to values from other regions. Continuous monitoring of the trophic state is essential for the sustainable management of Jinhae Bay's fisheries.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.111-119
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• 2015

The negative factors of fishery in environmental aspect of view are Greenhouse gas emission problems by high usage of fossil fuel, destruction of underwater ecosystem by bottom trawls, reduction of resources by fishing and damage of ecosystem diversity. Especially, the Greenhouse gas emission from fisheries is an important issue due to Canc$\acute{u}$n meeting, Mexico in 1992 and Kyoto protocol in 2005. However, the investigation on the GHG emissions from Korean fisheries did not much carry out. Therefore, the quantitative analysis of GHG emissions from Korean fishery industry is needed as a first step to find a relevant way to reduce GHG emissions from fisheries. The purpose of this research is to investigate which degree of GHG emitted from fishery. Here, we calculated the GHG emission from Korean bottom pair trawl fishery using the LCA (Life Cycle Assessment) method. The system boundary and input parameters for each process level are defined for LCA analysis. The fuel use coefficient of the fishery is also calculated. The GHG emissions from the representative fishes caught by bottom pair trawl will be dealt with. Furthermore, the GHG emissions for the edible weight of fishes are calculated with consideration to the different consuming areas and slaughtering process also. The results will be helpful to understand the circumstances of GHG emissions from Korean fisheries.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.97-103
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• 2009

It is a research that free floating larva of Ruditapes philippinarum in compliance with infiltration flow of tidal accumulation and bottom-clinging system in high density also, It is a precondition this for the continuous augmentation of Ruditapes philippinarum resources. So in flow field of tidal the free floating larva produced the infiltration water tank that can possibly bottom-clinging and experiment the water tank which uses free floating larva, It evaluates that the acceleration effect of free floating larva by infiltration in objective. As a result, 1) The experiment on free floating larva's bottom sediment grain diameter came to be high recording as bottom-clinging rate at the static water field and even biologically it selects bottom-clinging substrate it will be able to confirm. 2) About occurrence of infiltration flow field is in case of that: the drift of a current 10cm/s, bottom sediment grain 1.21mm infiltration flow 0.3cm/s increase of 3~5 times was confirmed. 3) From free floating larva of Ruditapes philippinarum the choice of bottom sediment grain diameter depends in the biological factor and form the flow field the bottom-clinging acceleration effect was controled over physical stable condition. 4) In case of density of Ruditapes philippinarum free floating larva of sea area, bottom sediment grain diameter, flow condition which are very cleanly in the research that possibly could conjecture the free floating larva's bottom-clinging rate.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.3
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• pp.179-187
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• 2005

This study was conducted in order to the experiment of bottom trawl fisheries in the sea mount of central northern pacific($30^{\circ}-40^{\circ}N$, $170^{\circ}-175^{\circ}E$), during the period of July 1 to August 25, 2004 by commercial trawl ship. Fishing experiment was carried out by bottom trawl, with the codend of 110mm mesh size. The number of 101 test fishing was done in the sea mount of central northern pacific during 56 days and the total catches were 198,593kg as 18 fish species, and CPUE/day and catches/day were 8.3 hours towing time and 3,546kg. Catch ratio according to each fishing ground was higher with the order of B, C, and E, and catches for B was 7,171.0kg during the towing time of 13.2 hours. Main target species were Pseudopentaceros richardsoni and Beryx splendens, there was 14.9% of damage ratio for fishing gears on catching the target fishes inhabiting on the rough sea bottom. Catches by water depth was the order of 300m below, 301-350m, 451-500m and 351-400m. It is thought that there was no problem on the mesh size because most of fishes caught from the experimental fishing was 30cm over.

• The Journal of Fisheries Business Administration
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• v.42 no.1
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• pp.1-18
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• 2011

This paper analyze a description of Korean fleet using bottom gears on the high seas. The need for this study arises from international moves to address the effects of fishing with bottom gears on vulnerable marine ecosystems (VMEs) and in view of a communication on the Korean policy in respect of this. There is growing concern over the impact of fishing using gears that come into contact with the seabed (bottom gears), in particular in deep-sea areas where vulnerable marine ecosystems including seamounts, hydrothermal vents and cold water corals are located. Korea is an important stakeholder in high seas bottom gear fisheries. For the past eight years, the issue of protecting biodiversity in the deep-sea in areas beyond national jurisdiction has been extensively debated by the United Nations General Assembly (UNGA) and in other international fora. As a result of the report and a review by the UNGA of the effectiveness of the measures called for in resolution 59/25, the UN General Assembly called for a series of specific actions to be taken by States and RFMOs in UNGA resolutions 61/105 in 2006 and 64/72 in 2009 adopted by consensus. Korea attaches great importance to the protection of marine ecosystems and has made active efforts to implement the UNGA Resolution 61/105 in areas where there is a regional fisheries management organization, a process of establishing such organization or no such multilateral regime. For the effective implementation of the UNGA Resolution 61/105 and 64/72, Korea views that the development of support tools and, most importantly, the development of a global database on VMEs are urgently needed because many countries lack the ability to identify VMEs and to assess whether individual bottom fishing activities would have significant adverse impacts on their own.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.4
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• pp.304-311
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• 2008

Patagonian toothfish(Dissostichus eleginoides) was investigated in the southeastern Atlantic Ocean during the period of 19 March to 7 July 2007 by commercial bottom longliners. The number of 116 hauls were carried out individually in this study area by two bottom longliners during 111 days. The total catches were 89,559kg(9.91kg/100hooks) and 66,758kg(7.38kg/100hooks), respectively. Most Patagonian toothfishes were caught on the $46-48^{\circ}S$, $6-11^{\circ}E$ of southeastern Atlantic Ocean. Patagonian toothfish comprised 67.01-92.49%(by weight) of the catches in the southeastern Atlantic Ocean. No Antarctic toothfish (Dissostichus mawsoni) was caught during the surveys. Patagonian toothfish was found throughout the experimental area, but the density was considerably greater in the layer of 1,300-1,900m, where 49.88% of the fishes were caught. Smaller fishes were generally distributed to the shallow waters and larger fish were more frequently caught with the depth. Mean size of Patagonian toothfish increased with depth of capture. Accordingly economically profitable fishing activities for the Patagonian toothfish fishery requires an understanding of the size distribution of the Patagonian toothfish by depth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.393-403
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• 2016

A steady, strong southward flow was observed in the lower layer beneath the Tsushima Warm Current in the deepest trough of the Korea Strait. Known as the Korea Strait Bottom Cold Water (KSBCW), this bottom current had a mean velocity of 24 cm/s and temperatures below 8–10℃. The direction of the bottom current was highly stable due to the topographic effects of the elongated trough. To determine the path of the southward bottom current, ADCP (Acoustic Doppler Current Profiler) data from 14 stations between 1999 and 2005 were examined. Persistent southward flows with average speeds of 4–10 cm/s were observed at only three places to the north of the strait where the bottom depths were 100–124 m. The collected data suggest a possible course of the southward bottom current along the southeast Korean coast before entering the deep trough of the Strait.