• Animal cells and systems
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• v.8 no.3
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• pp.231-233
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• 2004

Sequences of cytochrome b gene and control region of mitochondrial DNA from Korean common otters (Lutra lutra lutra L.) were examined to provide the genetic information for the conservation of this subspecies. Two haplotypes and one haplotype were revealed in cytochrome b gene and control region, respectively. The available sequences of European common otter (L. l. lutra) from GenBank were compared together with those of Korean common otter in order to determine the degree of sequence variation between them. In cytochrome b gene sequences, two haplotypes from Korea and two haplotypes of Europe showed differences in 12 of 1,045 sites. The Tamura-Nei nucleotide distances between two European haplotypes was 0.10% and those between two Korean haplotypes was also 0.10%, but those between Korean haplotypes and European ones ranged from 0.96% to 1.16%. In the control region, one Korean haplotype and seven European ones showed differences in seven of 300 sites; the Tamura-Nei distances among seven European haplotypes were 0.34% to 1.01%, but those between Korean haplotype and European ones ranged from 1.01% to 1.69%. Although further molecular and morphological studies with specimens from eastern Asia including Amur region and northeast China are needed, it is possible that the Korean common otter might be closer or identical to the far-eastern Asian common otter, L. l. amurensis Dybowski.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.49-55
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• 1986

The authors carried out an experiment to determine the horizontal opening of the mid water trawl gear, which is the same as was used in the foreward experiment concerned to the attitude and opening efficiency of otter board. The trawl net .used in the experiment was designed to have a square sectional four-seamed body with two three-sepenlted wings. Each wing tip was rigged with a net pendant of 70 m long and the fore ends of the pendants were directly jointed to the otter pendant without inserting hand rope, and a front weight of 200 kg weigh was rigged with in front of the lowest wing tip. To determine the opening between otter boards ani between wing tips, two 50 KHz fish finders were set sideways on the otter board and on the port middle wing tip so as to detect the distance froa the finders to the starboard otter board and to the wing tip respectively, and the informations were transmitted to the indicators onboard the ship through water-tight cables. The results obtained can be summarized as follows: 1. The openings between otter borads were 43-45 m in case of the warp 100 m, 53-55 m in the war;> 150 m and 54-59 m in the warp 200 m. It was increased in linear according to the increase of towin; speed in the range of 1. 1-1. 8 mlscc. 2. The determined values of the openings between otter boards were greater than the estimated values. which were calculated by the opening between warps at the gallows of the ship and the length of tt~ warp, assuming that the warps from the top rollers to the otter boards were straight. The rates of the determined values to the estimated values were 1. 23-11. 0 in case of the warp 100 m, 1. 23-1. 12 in the warp 150 m and 1. 23-1. 15 in the warp 200 m respectively. The rates were almost the same at the slow towing speed of 1. 3 mlscc or so, then the higher the speed, the less the rate, and the longer the warp, the greater the rate. 3. The rates of the openings between otter boards to the total length of net pendant and the net (excluded cod end) showed 43-43% in case of the warp 150-200 m. It was a little smaller than th~ standard. which is 50%. in the common bottom trawl. 4. The determined openings between wing tips were 18-19 m in case of the warp 100m, 21-22 m in the warp 150 rn, They showed that the higher the speed, the greater the openings even though its range was no more than 1 m or so. 5. The rates of openings between otter boards to th~ openings betwee:l wing tips were almost invariably 38%. 6. The rates of openigs b2tween otter boards to the lenth of h~ad rope were 60-65% in cas': of th~ warp lOa-150m. It were much larg2r than th~ standard. which is 50%. in the common botto:n trawl.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.66-73
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• 2014

In order to determine whether vegetation would be one of the factors for the selection of otter home range, vegetation structure and other potential factors were studied in Hwacheon, Korea. Thirteen sites, otter's activity found and not found, were investigated in North Han River and connected tributary streams of Hwacheon-gun. Three types of vegetation were classified by cluster analysis, which is short grass, tall grass and shrub type. Vegetation zone of each channel is composed of either one type, or mosaic of tall grass and shrub type. Short grass type is common in Lake Paro and upper North Han-river where water level is highly variable throughout a year. Therefore, annual species such as Persicaria nodosa, Fimbristylis dichotomam and Chenopodium ficifolium are the most dominant. Shrub type is common at the downstream sites of Jichon stream and along mainstream of North Han River down Lake Paro. A shrub species, Salix koreensis, is the most common. Tall grass type is dominant occupying the most vegetation zone of the tributary channels. Phragmites japonica is absolutely dominant. Due to its dense cover, a few plant species are co-existed. Otter activity was found in all three vegetation types and no marked activity was found at some sites of tall grass type. There is no difference in species composition and physiognomy between tall grass sites with and without otter activity, while it shows significant difference in fish availability between two groups. Overall we found that home range of otters in the region is along the mainstream and downstream of tributary streams with high fish availability in all vegetation types and in various human activity levels.

• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.297-305
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• 2009

The Asian paddle crab, Charybdis japonica (A. Milne-Edwards) is an important fishery resource in Korea. Despite its common occurrence and commercial importance, few studies have been carried out on the life cycle and trophic ecology of these populations inhabiting on the tidal flat. Food habits of C. japonica populations were investigated on the Jangbong tidal flat, Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. Based on the examination of stomach contents from 257 individuals, the frequencies of occurrence and the relative volumes of food items were analysed. As a result, the crustaceans (the brachyura, the cirripedia and the harpacticoid copepoda), the echinoderms (the ophiuroidea) and the molluscs (the cephalopoda Loligo beka, the bivalves Bivalvia unid. and Mytilus galloprovincialis) were important food for this species. To examine ontogenetic shifts in diets, individuals of C. japonica were categorized into 2 different size classes (${\leq}60mm$ and ${\geq}61mm$ in carapace width) representing sexually premature and mature stages. The food items of the small crabs (${\leq}60mm$) were dominated by the crustaceans with the harpacticoid copepods constituting 84.6% of total prey number. The next group was the bivalves and the brachyurans. On the other hand, the large crabs (${\geq}61mm$) mainly feed on the bivalvia (Mytilus galloprovincialis and Bivalvia unid.), the brachyurans (Crab unid.) and occasionally the cephalopods and fishes. The difference in proportions of the main prey items among these two size classes was statistically significant. Therefore, the feeding habits of the portunid crab, C. japonica changed with growth.

• Journal of Fisheries and Marine Sciences Education
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• v.6 no.1
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• pp.11-19
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• 1994

The North Pacific midwater trawling which is one of the important fishing methods for Korean fishing industry is working in the Bering Sea and the sea near Kamchaka Peninsula. The catch by Korean midwater trawlers had been recorded about 300 thousands $^{M/_T}$ a year. Six types of midwater trawl net-ordinary midwater trawl net, super-V trawl net, super mesh trawl net, rope trawl net, super plus trawl net and kite trawl net-have been widely used by large trawlers above 1,500gt in size since 1982. Regarding the fishing efficiency, the super plus trawl net and kite trawl net were acknowledged as higher than other nets. Maximum mesh size of super-plus trawl net and kite trawl net ranges about 20m, whereas the length of net about 150m, and high-tech polyethylene is used as the material of rope part. The problems involved in the North Pacific midwater trawl net may be summarized as follows ; (1) The dimension of fishing gear is too big compared with the towing power of trawler. (2) The mesh size of the rope part is too big compared with that of the common netting part. (3) The net is often torn out in the connecting position of the rope part and the netting part. (4) The net is not matched with the trawler and the otter board in many trawlers, so the shape of the trawl gear in the water is instable. (5) The fish school located near head rope, ground rope and side rope in the net recorder is not caught in practice because of the net instability.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.3
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• pp.51-58
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• 2006

The purpose of this research presents a method to position and makes the structure for eco-corridors reasonably with collectable analysing results of various effects shown in mammals' road-kill at 429 points. Target animals of this research are Leopard cat, Siberian weasel, Raccoon dog, Korean hare, Eurasian red squirrel, Siberian chipmunk and Water deer. The results derived from the empirical analysis on the contents above are followed. First, according to the results as for Leopard cat road kill analysis, which is designated as Endangered Species Class II, the eco-corridor might be located at near village having stead food in order to decrease the frequencies of road-kill, because its road kill points were mainly collected at 4 lane hilly road with mountain-road-farm area geological type of. Second, because Siberian weasel's road kill was detected at 2 lane hilly road with mountain-road-stream geological type, the eco-corridor might be located at near a mill to decrease road-kill frequencies. Third, the road-kill frequency of Eurasian red squirrel can be reduced when the eco-corridor is located at the area across coniferous tree near 4 lane west sea freeway with mountain-road-mountain. Fourth, the road-kill of Raccoon dog can be reduced when the eco-corridor is located at 4 lane mountain road or hilly road with the geological type having farm land-road-mountain(stream). Fifth, Korean hare's road-kill can be reduced when the eco-corridor is located at grass land across ridge line of mountain, because wild rabbit road kill was happened at 4 lane mountain road or 2 lane mountain road(mountain-road-mountain). Sixth, As for Siberian chipmunk, the eco-corridor might be located at the side slope of mountain road at 2 lane mountain road under the speed of 60km/h with mountain-road-mountain. Seventh, For Water deer, the eco-corridor might be located at 4 lane hilly road with mountain-road-farm land. As for Common otter, Amur hedgehog, Yellow-throated marten, Weasel, it is difficult to specify the proper site of eco-corridor due to the lack of data. Eco-corridors for carnivores might be well located at 4 lane hilly road or 2 lane hilly road with mountain-road-farm land, and the track for herbivores might be well located as a overhead bridge on mountain-road-mountain type across mountains. In order to position eco-corridors for wildlife properly, we have to research animal's behavior with ecological background, and to consider the local uniqueness and regularly collect the empirical road-kill data in long term 3 to 5 year, which can be the foundation for the more suitable place of wild life eco-corridors.