• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.594-604
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• 2017

The Korean National Institute of Fisheries Science (NIFS) has biannually (spring and fall, respectively) deployed a bottom trawl survey along the coastal areas for last decade, taking samples on a regular basis (i.e., a systematic sampling). Despite the availability of the survey data, NIFS has not yet officially reported the estimates of the groundfish population sizes as well as has not evaluated uncertainty of the estimates. The objectives of our study were to infer the relative size of a fish population, applying two different sampling techniques (namely simple and stratified sampling) with different observation units to the NIFS survey data, and to compare those two techniques in bias and precision. For demonstration purposes, we used data on Pacific cod (Gadus macrocephalus) collected by the 2011-2015 surveys, and the results of simple and stratified sampling showed that the point estimates and precision varied by observation unit as well as the sampling technique.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.484-492
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• 2015

The purpose of this study is to compare the ichthyofauna between the eelgrass bed waters located in the open sea and the nearby sea free of eelgrass, and this study collected a total of 26 species. Comparing the fish collected on the eelgrass bed (St.2) of Geomun-do coast with the fish collected on the coastal waters (St.1) void of the nearby eelgrass bed, the fish collected from the eelgrass bed included 19 species, 413 individual with 16,110.6g in weight while the fish collected from the coastal waters void of the eelgrass bed included 19 species, 290 individuals with 12,961.5g in weight. Accordingly, it was found that the population size and biomass of the fish collected from the eelgrass bed were higher than the coastal waters void of the eelgrass. This study could identify that diversity, richness, evenness index except dominance were also much higher even in the result of cluster analysis.

• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.219-225
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• 2001

The gamma-radiation sensitivity of three kinds of pathogenic bacteria to fish was investigated. $D_{10}$ values (irradiation dose required to inactivate 90% of the population) of Edwardsiella tarda, Vibrio anguillarum and Streptococcus faecalis were 0.08, 0.10 and 0.44 kGy, respectively. The inactivation factors were 4.50 - 24.30 and 6.75 - 36.45 at radiation doses of 2 and 3 kGy. Raw moist pellets were inoculated with Edwardsiella tarda, Vibrio anguillarum or Streptococcus faecalis. Inoculated feed samples were packaged in air and irradiated at 5 kGy. This dose was effective in controlling the inoculated and general bacteria in fish feed. We consider gamma-radiation to be an effective method to sterilize pathogenic bacteria in fish feed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.128-141
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• 2024

Fish resource surveys were conducted near Jeju Island in June, August and October 2021 using an underwater camera monitoring system, fish pots, and SCUBA diving methods. The efficiency of the methods used to survey fish resources was compared using the number of individuals compared to area per unit time (inds/m³/h) and the number of species compared to area per unit time (spp./m³/h). As a result of comparing the number of individuals compared to the area per unit time (inds/m³/h), the order was underwater camera 214.69, SCUBA diving 124.62, and fish pots 0.57 inds/m³/h. The number of species compared to area per unit time (spp./m³/h) is in the following order: SCUBA diving 0.85, underwater camera 0.38, and fish pots 0.01 spp./m³/h. The fish resource monitoring method using underwater cameras was found to be more efficient in individual counts, and the SCUBA diving method was found to be more efficient in species counts. When considering cost and survey efficiency, the fish resource survey method using underwater cameras was judged to be more effective. The results of this study are expected to be widely used in estimating the population density of fish, which is the core of future fisheries resource surveys.

• Korean Journal of Environment and Ecology
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• v.25 no.1
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• pp.65-70
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• 2011

The fish fauna and population of Zacco koreanus in the upper region of the Gapyeong Stream was investigation from April, 2005 to August, 2009. The collected species during the survey period were 16 species belonging to 6 families. Dominant species was Z. koreanus and subdominant species was Pungtungia herzi. korea endemic species were Pseudopungtungia tenuicorpa, Coreoleuciscus splendidus, Hemibarbus mylodon, Gobiobotia brevibarba, Microphysogobio longidorsalls, Z. koreanus, Koreocobitis rotundicaudata, Iksookimia koreensis, Silorus microdorsalis, Liobagrus andersoni, Coreoperca herzi and Odontobutis platycephala, which showed a ratio of 75 % in all collected species. The species of H. mylodon was identified as natural monument, and P. tenuicorpa and G. brevibarba were endangered species. Length-weight relationship in the population of Z. koreanus was 3.44, and condition factor in the popuation was 0.004. The spawning season of Zacco koreanus was May and June.

• Korean Journal of Environment and Ecology
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• v.25 no.1
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• pp.71-80
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• 2011

The fish fauna and characteristics of population of Zacco platypus in the 9 microhabitat at the Tan Stream was investigated from August, 2009 to April, 2010. The collected species during the survey period were 17 species belong to 7 families. Korea endemic species were Hemiculter eigenmanni and Odontobutis interrupta, which showed a ration of 11.8% in collected species. Dominant species was Z. platypus and subdominant species was Carassius auratus. Dominated species of C. auratus was at the dam-type pool, Meander-type pool, run, and rock-type pool, Pseudogobio esocinus was side channel, Rhinogobius brunneus was riffle, and Z. platypus was channel connected pool, substrate-type pool and channel unconnected pool. Length-weight relationship in the population of Z. platypus was 3.29. PCA analysis was in to the 3 groups identified. Bary-curtis cluster analysis indicated that the substrate-type pool and channel unconnected pool 65.9% showed the most similar, riffle, and dam-type 30.4% were identified as the most contrast.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.228-232
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• 1970

From the standpoint of fishery science it is an interesting matter to note that the size of Plecoglessus altivelis population on Cheju Island is smaller than that of the Nakdong River located in the southern part of Korea's mainland. Therefore the author carried out a comparative analysis to determine whether the populations differ because of racial or because of environmental conditions. The morphometric characters of the head length and the body length were used for the analysis of covariance and computed by a standard regression method of testing for the homogeneity of the populations. All samples were collected during 1968 and 1969 in the Milyang Stream of the Nakdong River and the Cheonji Stream of Cheju Island. The results of the analysis of the populations based on the significance test are as follows: 1. Since the F value observed was only 1.023 ($n_1=1,\;n_2=42$) the conclusion was reached that the samples could both belong to the same population. 2. In comparison with the deviations of the regression coefficients between the fish of the Nakdong River and Cherinji Stream, the populations were also highly significant suggesting that thelr belong to the same population. 3. The conclusion is that the fish of Cheju Island became a smaller fish in size due to an environmental condition but not due to racial characteristics.

• Korean Journal of Environment and Ecology
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• v.22 no.2
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• pp.184-191
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• 2008

To investigate the effect of turbid water on fish population, the length-weight relationship and its condition factor were applied to Kumgang fat minnow Rhynchocypris kumgangensis collected in turbid (the Daegi and the Jaun streams) and non-turbid stream (the Bongsan and the Gyebang streams) for a year from 2004 to 2005. The mean length of minnow between turbid water and non-turbid water streams was not significantly different. In the South River system, the regression coefficients (b) based on length-weight relationship were 3.21 in the non-turbid Bongsan stream and 3.07 in the turbid Daegi stream, respectively. On contrary, the regression slope in the turbid stream was a little higher than that of the non-turbid stream located in the Bukhan River system. The values were 3.20 in the Gyebang-stream and 3.23 in the Jaun stream, respectively. Our result suggested that chronic turbid water effect on the level of fish population has a little or no effect.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.196-206
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• 2005

The fish community in the mid-upper region of Gam Stream was examined seasonally from 2001 to 2003 in order to perform an environmental impact assessment prior to a construction of Gamcheon Multipurpose Dam. Additional investigation was conducted in August 2004 to confirm the fish fauna reported and to examine the ecological characteristics of Zacco temminckii population. The total number of fish caught from the study sites was 1,081 fish representing 5 families 14 species. There were 6 Korean endemic species including Coreoleuciscus splendidus, Squalidus gracilis majimae, Microphysogobio yaluensis, Liobagrus mediadiposalis, Coreoperca herzi and Odontobutis platycephala, but no endangered or vulnerable species were found. Length-weight relation, condition factor (K) and relative condition factor (Kn) of Zacco temminckii were compared by the study sites and stream. The equations based on length-weight relation in Buhang and Gam Streams were TW\;=\;0.000004TL^{3.2357}$ and TW\;=\;0.000002TL^{3.3566}$, respectively indicating the fish in Gam Stream became more rotund as length increases. The condition factor (K) and relative condition factor (Kn) against total length of Zacco temminckii at two streams indicated that the fish (>70 mm) in Cam Stream (mean K and Kn= 1.116, 1.21 respectively) had better nutritional condition than those in Buhang Stream (mean K and Ln = 1.046, 1.14 respectively). The results were corresponded with natural disturbances such as drought and intensive rainfall from 2001 to 2003 followed by human activities such as stream repair works. Therefore, it is considered to perform environmental impact assessment with not only confirmation of fish composition but also examination of ecological characteristics in population- level.

• The Korean Journal of Ecology
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• v.6 no.4
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• pp.10-20
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• 1983

Morphological and ecological comparions are made between specimens of Cobitis koreensis KIM and the geographically restricted population of the Cobitid fish which is found along the Begchon stream, Puangun, Cholla-bugdo province over a 12-month period of 1982 and 1983. The Begchon population is tentatively identified as Cobitis koreensis, but the color patterns and two morphometric proportions differ widely fromthose reported previously for this species. In addition to these character, it is easily distinguished from C. koreensis by the smaller body size, by having the larger egg size and the less egg number in female during the breeding season. As the differentiation of this population is primarily due to geographically isolation, it is supposed that Begchon cobitid population may be an undescribed distinct subspecies of K. koreensis or above the conventional subspecies level.