• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.719-724
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• 2019

This study is an extension of our previous model for a size-based fish stock assessment. In the previous model, we applied an allometric length-weight relationship (W=α·L^β) to convert lengths of fish to weights, and estimated those parameters α and β, using data about lengths and weights aggregated over years. In this study, we focused on whether consideration of temporal (e.g., year-to-year) variability in those estimates (i.e., ${\hat{\alpha}}$ and ${\hat{\beta}}$) would contributive. After calculating year-specific estimates (i.e., year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$) by applying data about lengths and weights separated by year, we evaluated the contribution of those year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$ to the performance of the size-based stock assessment model. The model with such year-to-year variability being considered (lower AIC) outperformed that with the variability being ignored (higher AIC). We illustrated this study using data on Korean chub mackerel Scomber japonicus from 2005-2017.

• Development and Reproduction
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• v.23 no.2
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• pp.161-170
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• 2019

The purpose of this study is to investigate the development of Coreoleuciscus splendidus egg and larvae morphology in the Ungcheon-stream. C. splendidus eggs were round and ranged in size from 1.86-2.01 mm (mean $1.91{\pm}0.14mm$). Immediately after hatching, the larvae had egg yolk in the abdomen with a total length of 5.27-6.63 mm (mean $5.95{\pm}0.96mm$). On the 10 days after hatching, the latter was 8.44-8.65 mm (mean $8.54{\pm}0.14mm$) in total length, and 5 dorsal fin rays were formed in dorsal fin and 8 caudal fin soft rays were formed in caudal fin. At 88 days after hatching, total length was 26.2-25.7 mm (mean $25.9{\pm}0.35mm$), and scales were formed throughout the body. The fin rays of each part were iii.7 in dorsal fin and iii.6 in anal fin, and finally the external form was the same as the adult fish.

• Journal of fish pathology
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• v.2 no.1
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• pp.37-44
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• 1989

This study was taken to induce either anaesthesia or sedation for the purpose of applying to transport of live fish safely. 7 species of fish in addition to Tilapia mossambica were exposed to 250 ppm concentration of the anaesthetic quinaldine to determine the safe level for handling and transportation of these species. The results obtained are as follows ; 1. The time taken to lose balance increased with a decrease on the concentration of the anaesthetic. 2. Anaesthetization must be carried out under temperature lower or higher rather than optimum temperature. 3. The longer the length of the fish, the longer the anaesthetization time and recovery time of fish. 4. Coefficient of recovery period and body length is 0.78. 5. At 10-15 min. after anaesthetization, the serum levels of glucose, ALP and SGOT were at peat. 6. LDH of the anaesthetized fish is much more increased than that of the unanaesthetized. 7. In the more 250 ppm treatment, the pyknosis of the brain and spleen tissue appeared.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.549-556
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• 2022

The aim of this study was to evaluate the genetic parameters of growth traits for improvement breeding in olive flounder Paralichthys olivaceus at the 8^th generation of selective breeding in April 2021. Growth traits such as total length, body weight and condition factor at 11 months of age were measured for 7,508 individuals with confirmed paternity. Data were analyzed using the restricted maximum likelihood method applied to a multiple traits animal model. The effects of sex and family were significantly different across traits (P<0.05). The heritability values of total length, body weight and condition factor were estimated to be high as 0.479, 0.457, and 0.466, respectively. Correlation analysis between phenotypic and breeding values, indicated that the selection accuracy was 75.9-85.2% for all traits. To increase the selection accuracy for parent fish selection, the sex and pedigree characteristics that affect each trait should be considered. Moreover, further improvement of multiple traits can be achieved if the correlation between each trait is appropriately considered.

• Fisheries and Aquatic Sciences
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• v.25 no.7
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• pp.380-389
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• 2022

Morphometric relationships, condition factor (CF) and reproductive biology are significant tools in fish stock management, fish biology, physiology, conservation and ecology. Growth and reproductive strategy of Oreochromis niloticus were studied from 343 fish specimens collected from Lake Shala between January and December 2018. Fish samples ranged from 7.7 cm to 33.0 cm in total length (TL) and from 7.80 g to 708.21 g in total weight (TW) were collected using gillnets of 4, 6, 8, 10, and 12 mm mesh sizes. The length-weight relationship of O. niloticus was TW = 0.0104TL^3.19, indicating positive allometric growth of the fish. The sex ratio (0.93:1) was insignificant from the ideal fish distribution of 1:1 (χ² = 0.47, p > 0.05). Mean CF for males, females and combined sexes was 1.04, 1.06 and 1.05, respectively and statistically insignificant (p > 0.05). The spawning peak occurred in July (rainy) and February (dry) periods, as defined by ripe females and the breeding season. Absolute mean fecundity was 806 eggs and correlated positively with TL and TW of the fish (p < 0.05) (F = 0.56TL^2.29, R² = 0.93, p < 0.05; F = 18.83TW^0.67, R² = 0.90, p < 0.05). The study provides the first detailed account of the morphometric relationships and reproductive biology of O. niloticus in Lake Shala, which can be used as baseline information for successive biological-based studies in Soda Lakes of Ethiopia.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.929-935
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• 1997

The total energy of fish movement and the maximum burst swimming speed were estimated and formulated in accordance with body length and water temperature for several species in fisheries by empirical methods and also by using published results. Under the assumption of swimming energy reserve of a fish at the initial rest state, the swimming endurance of fish with different body lengths, swimming speeds and angular velocity was calculated using the relevant equations under similar conditions in tank experiments as well as natural conditions in field. Relative swimming energy efficiency or the transition swimming speed between red and white muscle for energy consumption was represented as a trigonometric function of swimming speed ratio. Therefore, this model does closely approach the actual swimming abilities and their limits especially in relation to the fishing gear operation and allow for the greater vitality of the wild fish in the fields.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.333-341
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• 2022

Despite rapidly increasing demand for fishing, there is a lack of studies and information related to fishing, and there is a limit to obtaining the data on the global distribution of fish resources. Since the existing method of investigating fish resource distribution is designed to collect the fish resource information by visiting the investigation area using a throwing net, it is almost impossible to collect nation-wide data, such as streams, rivers, and seas. In addition, the existing method of measuring the length of fish used a tape measure, but in this study, a FishingTAG's smart measure was developed. When recording a picture using a FishingTAG's smart measure, the length of the fish and the environmental data when the fish was caught are automatically collected, and there is no need to carry a tape measure, so the user's convenience can be increased. With the development of a global fishing application using a FishingTAG's smart measure, first, it is possible to collect fish resource samples in a wide area around the world continuously on a real time basis. Second, it is possible to reduce the enormous cost for collecting fish resource data and to monitor the distribution and expansion of the alien fish species disturbing the ecosystem. Third, by visualizing global fish resource information through the Google Maps, users can obtain the information on fish resources according to their location. Since it provides the fish resource data collected on a real time basis, it is expected to of great help to various studies and the establishment of policies.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.4
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• pp.404-409
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• 1999

The in situ target strengths of, maurolicus muelleri were measured by the split beam echo sounder system at the frequency of 38kHz.Target strengths were measured during the night time in order to obtain the pure separated echoes from the scattered individual. And also it was to establish reasonable threshold due to taking the signals like as the planktons and etc.Since Maurolicus muelleri is a typical micronektonic fish, they mainly consisted of deep scattering layers(DSLs), and had a vertical migration perrodically during daytime and at night.We found that the Maurolicus muelleri occupied about 99% of total catch. Total length ranged from 4.5 to 5.7cm with a mean of 5.2cm and a standard deviation of 0.22cm.The target strengths of Maurolicus muelleir ranged from -60.4 to - 52.7dB and -59.2 to - 52.5 dB in the water layer of 10~30m and 30~50m depth, perspectively. Mean target strength was -57.1dB/fish and -28.5dB/kg. The target strength had the relation with the total length of the fish as, TS=20logL-71.4.

• Fisheries and Aquatic Sciences
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• v.11 no.3
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• pp.133-139
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• 2008

Molecular techniques, including restriction fragment length polymorphism(RFLP) and polymerase chain reaction-single strand conformational polymorph isms(PCR-SSCP), were developed to identify salted, dried threadfin(Eleutheronema tetradactylum) and white herring(Ilisha elongata) fish. Using PCR with universal primers, conserved 367-bp fragments of the cytochrome b gene were amplified from fresh fish samples and sequenced. The sequences were then searched for specific restriction sites. The digestion of the PCR products with the endonucleases AvaI, FokI, MboII, and MspI generated RFLP, which was used to identify the commercial products. Similarly, the amplified PCR-SSCP products were developed and the products tested. Overall, similar patterns were found in the majority of the fresh and processed products. Based on the results, both RFLP and PCR-SSCP were useful in determining and validating the authenticity of the fish species used to prepare the commercial salted, dried products. A similar approach can be applied to other species.

• Fisheries and Aquatic Sciences
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• v.21 no.3
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• pp.12.1-12.15
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• 2018

A preliminary investigation of length-weight relationship, condition factor and reproductive ecology of African pike fish, Hepsetus odoe, was conducted between June to August 2010 in Lake Eleiyele. A total of 90 samples of the fish species were caught by fishermen using gill nets. The results obtained showed that fish species had isometric growth pattern (contrary to negative allometry expected) with the growth exponent, b value of 2.64, that is not statistically different from 3 and with high statistical power of 0.866 when tested. The mean condition factor, K, was found to be 2.6, indicating that the fish species were in good condition in the study area. For reproductive biology, mean fecundity and gonadosomatic index were found to be 1349 eggs and 3.53% respectively. This study was necessary to fill the knowledge gap and provide information for management and conservation of the investigated species in the lake system. This study recommended that further research needs to be conducted because the sampling was carried out in the rainy season period and within a quarter of a year.