• Journal of Ecology and Environment
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• v.47 no.2
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• pp.42-48
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• 2023

An adult male Eurasian river otter (Lutra lutra) with ataxia and lethargy was rescued. Through the necropsy of this otter with neurological symptoms, a broad range of vascular damage caused by mercury toxicity in several organs, hepatocellular necrosis, and vacuolation in the brain. In mercury examination, liver, kidney, and hair showed values of 0.878 ± 0.027, 1.807 ± 0.049, and 5.712 ± 0.102 ㎍/g, respectively. Compared with certified reference material, it was confirmed that the concentration of mercury were 6.7 times, 13.7 times, and 43.3 times higher, respectively. When the symptoms and diagnosis results were comprehensively reviewed, this otter's demise was revealed due to mercury poisoning. The mercury concentration in the liver does not exceed the lowest observed effect level of 3.4 ㎍/g. However, even at low concentrations, long-term accumulation can cause symptoms including neuropathy, and the possibility that these heavy metals have accumulated in other wild animals cannot be ruled out. It seems that continuous monitoring using sentinel animals is necessary.

• Journal of Veterinary Clinics
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• v.41 no.1
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• pp.54-59
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• 2024

A 12-year-old female small-clawed Asian otter (Anoyx cinereus) with a one-week history of anorexia, chills, and abdominal distension was found dead. Grossly, yellowish-brown turbid fluids accumulated in abdominal cavity of the otter, and yellowish thread-like fibrinous materials were found on the surface of abdominal organs. Several variable sized yellowish-white crystalloids were scattered on the medullary space of kidneys. Histologically, diffuse serositis (peritonitis) characterized by the fibrinous exudates, thickened serosal capsule and the swelling of mesothelial cells were observed in the serosa of liver, spleen, stomach, and intestine. Multifocal necrosis, hemorrhage, infiltration of macrophage, and brown pigments were presented in the liver. Isolated bacteria from ascites and fibrinous materials in abdominal visceral surface were white, smooth and convex with characteristic mousy odor on blood agar plate. These bacteria were confirmed as Pasteurella (P.) multocida type A by polymerase chain reaction analysis. Based on the gross examination, histopathologic findings and bacterial experiments, this otter was diagnosed as severe peritonitis associated with P. multocida and necrotic hepatitis.

• Journal of Species Research
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• v.1 no.2
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• pp.240-248
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• 2012

We used a non-invasive technique with microsatellite primers to investigate genetic variation among Eurasian otters Lutra lutra in eastern South Korea. We collected twenty two otter spraints in January and six in August 2008. We used spraints from five dead otters from five different river systems for the present genetic analysis. We extracted DNA from 20 spraints from the January sample. Ten microsatellite primers (Lut435, Lut453, Lut457, Lut604, Lut615, Lut701, Lut715, Lut717, Lut733, and Lut832) for Eurasian otters were tested, and four loci were successfully amplified for further analyses. The results of genotyping the otter population with microsatellite loci lead to the identification of 9 individuals from the Ungokcheon Stream. The Ungokcheon population also showed a genetic structure represented by the Hardy-Weinberg equilibrium.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• autumn
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• pp.3-12
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• 2004

• 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.37 no.1
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• pp.1-8
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• 2001

This study deals with the experimental and numerical investigations to design the high performance otter board. Experiment was carried out to determine the most effective slot size of single-slot cambered otter board in the circulation water channel of BAEK KYUNG IND. Co. LTD. Numerical analysis was done by the commercial CFD code, FLUENT, to provide some valuable physical interpretations and finally to design the otter board section by numerical method. The major results are as follows ; 1. In experiment, the maximum lift and drag coefficients of simple cambered type otterboard were 1.41, 0.55, respectively, at the angle of attack $28^\circ$, while those of slot one with slot size 0.02C (C denotes the chord length) were 1.72, 0.42 at the angle of attack $24^\circ$. 2. The hydrodynamic characteristics depending upon slot size shows the greatest at 0.02C of the slot size. 3. Numerical results well visualized the streamlines, pressure fields, and speed vectors of a simple cambered and slot cambered otter board with slot size 0.02C. The slot cambered one with slot size 0.02C was shown that pressure field was distributed moderately on front and back side of otter board. And, the delay and decrease of separation were favorably achieved by flow through slot. 4. Computed result on the pattern of hydrodynamic field and the values of $C_L$ and $C_D$ by the commercial CFD code, FLUENT, show almost the same as those of the experimental result.

• Spatial Information Research
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• v.12 no.1
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• pp.29-42
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• 2004

This Study was Analysis about Habitat of Eurasian otter Lutra lutra L. In October 2002 during September 2003, Otter Spraints and Sprainting site were searched in river Unkog of North-Kyongsang Province for taking the GPS coordinates. For Analysis of habitat, This data were used by Arcview ver. 3.2 with 1/25000 Topology Map and Other Field data. The result of Habitat Analysis meant that Habitat use was strongly related to Fish diversity and richness also vegetation and cover were connected with otter habitat. In other hand, The Human interferences including dense structures like House acted as factor of disturbance. This study suggest that The preceding about Suitable habitat having free of Human disturbance, abundant fish and good vegetation is essential In Trial for Conservation or Recovery of Otter like Trans-location.

• Journal of Animal Science and Technology
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• v.56 no.5
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• pp.16.1-16.9
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• 2014

Fatty acids (FA) have recently been used in several studies to infer the diet in a number of species. While these studies have been largely successful, most have dealt with predators that have a fairly specialized diet. In this paper, we used FA analysis as a tool to infer the diet of the nearctic river otter (Lontra canadensis). The river otter is an opportunistic predator known to subsist on a wide variety of prey including, fishes, crayfish, molluscs, reptiles and amphibians, among others. We analyzed the principle components of 60 FA from otters and 25 potential prey species in Illinois, USA. Prey species came from 4 major taxonomic divisions: fishes, crayfish, molluscs and amphibians. Within each division, most, but not all, species had significantly different profiles. Using quantitative FA signature analysis, our results suggest that, by mass, fish species are the most significant component of Illinois River otters' diet ($37.7{\pm}1.0%$). Molluscs ranked second ($32.0{\pm}0.8%$), followed by amphibians ($27.3{\pm}4.3%$), and finally, crayfish ($3.0{\pm}0.6%$). Our analysis indicates that molluscs make up a larger portion of the otter diet than previously reported. Throughout much of the Midwest there have been numerous otter reintroduction efforts, many of which appear to be successful. In regions where mollusc species are endangered, these data are essential for management agencies to better understand the potential impact of otters on these species. Our analysis further suggests that quantitative FA signature analysis can be used to infer diet even when prey species are diverse, to the extent that their FA profiles differ. Better understanding of the otter's metabolism of FA would improve inferences of diet from FA analysis.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.89-94
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• 2006

This study was conducted to infer habitat distribution of Eurasian otter Lutra lutra in Korea. We recognized trace or presence of otter spraints from 254 of 750 pixels (pixel size: 13.75X11 km) used in this survey, amounting to 34%. The highest frequency of localities, with the spraints present, occurred in Gyeongsangbuk-do (49.62%) and the lowest one was observed in Gyeonggi-do (7.36%). The other regions were as follows: Gangwong-do (49.56%), Chungcheong buk-do (41.67%), Gyeongsangnam-do (38.00%), Jeolabuk-do (37.93%), Jeolanam-do (24.24%), Chungchengnam-do (20.29%). The counted number of the spraints was very low level in most of the localities where they were found (1.7spraints per sprainting site). It may indicate that small size of local populations would be expected in most of the localities. The habitat distribution of Korean otter, inferred from the distribution pattern of the spraints, will provide valuable basic information required for conserving and managing Korean otter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.1
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• pp.1-5
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• 1987

The authors carried out an experiment to determine the vertical opening of the midwater trawl, which is the same used in the former experiment in this series of studies. To determine the vertical opening of otter board and front weight, three fish finders were used. A 200 KHz fish finder set on board the research vessel was used to sound the depth of water. A transmitter of 50 KHz fish finder was set through the shoe plate of otter board to determine the height of otter board from the sea bed, and a transmitter of another 50 KHz fish finder was set downwardly on the net pendant right before the front weight to determine the height of weight from the sea bed. The depth of otter board and weight were calculated by subtract the height of those from the depth of water, respectively. To determine the vertical opening of mouth, a transmitter of net recorder was set on the head rope and the vertical opening of that to ground rope was directly read on the recording paper. The results obtained can be summarized as follows: 1. The rate of the depth of otter board to the length of warp was in the range of 0.44 to 0.25, and the depth was linearly shoaled about 5m per 0.1m/sec of the towing speed or per 20rpm of the main engine. The rate of the observed depth to the calculated depth of otter board was in the range of 0.92 to 0.080 with a decreasing tendancy in accordance with the increase of towing speed. 2. The depth of head rope was 2 to 3m deeper than that of otter board, and the vertical opening of net mouth was in the range of 22 to 19m, with a decreasing tendancy in accordance with the increase of towing speed, 3. The difference of depth between front weight and otter board was about 20m and 22m respectively in the length of warp 100m and 150m without distinct change in accordance with the towing speed. The depth of front weight was 2 to 3m shallower than that of ground rope. 4. The changing range of depth of head rope according to the revolution of main engine was about 4m per 20rpm.