• Journal of fish pathology
• /
• v.13 no.1
• /
• pp.53-59
• /
• 2000

Presence of marine birnavirus (MABV) was examined against egg and ovarian fluid, and seminal fluid from the brood stocks of flounder, Paralichthys olivaceus collected from 9 different stations around Korean peninsula. The detection rate of MABV in brood stocks flounder was observed to 34% by PCR. The mean virus titer of the PCR positive fish was $10^{2.30}$ to $10^{4.30}$ $TCID_{50}$/g(ml). By a neutralization test, all of the isolated virus were ascertained to be closely related to marine birnavirus (MABV).

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.233-236
• /
• 2000

The acoustical response of fish depends on size and physical structure na, most important, on the presence or absence of a swimbladder. Acoustic scattering models for swimbladdered fish represent a fish by an ideal pressure-release surface having the size and shape as the swimbladder. Target strength experiments of red seabream (Chrysophrys major) have been conducted using 38 (split-beam), 120 (split-beam) and 200kHz (dual-beam) frequencies. At each start of each experiment, the live fish are placed in the cage at the surface, then the cage is lowed to about $4{\cal}m$ depth where it remains during the measurements. To test the acoustic models, predictions of target strength based on swimbladder morphometries of 10 red seabream offish total length from $103{\cal}mm{\;}to{\;}349{\cal}mm$ ($3 <$TL/\lambda$ < 45)are compared with conventional target strength measurements on the same, shock-frozen immediately after caged experiments. X-ray was projected along dorsal aspect to know the morphological construction of swimbladder. and fish body. At high frequencies, Helmholtz-kirchhoff(HK) approximation would greatly enhance swimbladdered fish modeling. Sound scattering model [HK-ray approximation model] for comparison to experimental target strength data was used to model backscatter measurements from individual fish. The scattering data can be used in the inverse method along with multiple frequency sonar systems to investigate the adequacy of classification and identification of fish

• Fisheries and Aquatic Sciences
• /
• v.23 no.5
• /
• pp.12.1-12.8
• /
• 2020

Background: An 8-week feeding trial was designed to evaluate the potential of yellow mealworm (MW; Tenebrio molitor) as a locally available nutrient-rich feedstuff for rainbow trout fry (Oncorhynchus mykiss). Methods: Triplicate groups of fish (mean ± SE; 1.11 ± 0.01 g) were assigned to each of the five isonitrogenous and isocaloric practical diets containing graded level of a full fat MW (0, 7, 14, 21, and 28%) at the expense of fish meal (designated as MW0, MW7, MW14, MW21, and MW28, respectively). Results: Fish growth performance in terms of weight gain and specific growth rate significantly increased with increasing dietary MW level up to 14% and then declined when dietary MW levels further increased to 28%. Significantly higher protein efficiency ratio and lower feed conversion ratio were found in fish fed with diets containing MW compared to fish fed the control MW0. Myeloperoxidase activity was significantly higher in fish fed MW7 diet compared to fish fed the MW0 diet. Fish fed the MW14 and MW28 diets had significantly higher lysozyme activities than those fed the MW0 diet. Conclusions: Overall, the efficacy of MW as promising alternative to fish meal in practical diets for rainbow trout fry has been proved not only in relation to growth rates and feed utilization, but also from the viewpoint of immunopotentiation effects.

• Ocean and Polar Research
• /
• v.30 no.1
• /
• pp.79-87
• /
• 2008

Hydroacoustic technique was used to analyze spatiotemporal stability and distribution of demersal fish aggregations in the coastal region to overcome some limitations of the existing methods such as net and diving. The survey was carried out in the Baekeum Bay on the south coast of Korea in January 2007. The bottom depth in the study site ranges from 7 to 25 m. In order to outline aggregations of demersal fish initial scanning using 200 kHz split-beam transducer was randomly conducted over the large area. Having detected fish aggregation in the specific region, intensive acoustic survey of irregular star pattern was carried out along 14 transects across the area in question. The results of the acoustic survey show that all demersal fish aggregations are concentrated about 5 m from sea bottom having a slight slope and remain steady with no spatial or temporal variations during acoustic survey. The hydroacoustic method used in this study offers a new approach to understand vertical and horizontal distribution, spatiotemporal stability, and biomass estimate of demersal fish aggregations in coastal regions. Additionally, the number of individual fish estimated from in situ acoustic target strength data can be used to understand the standing stock of demersal fish aggregation.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.53 no.3
• /
• pp.464-470
• /
• 2020

This study was conducted to replace fish meal (FM) with three plant proteins (soybean meal, soy protein concentrate, and wheat gluten) in diets for growing olive flounder Paralichthys olivaceus. The control diet was formulated to contain 65% sardine FM and four other replacement diets were formulated to replace FM with the plant proteins by 25, 30, 35 and 40% (designated FM25, FM30, FM35 and FM40, respectively). The replacement diets were added with three essential amino acids (lysine, methionine and threonine) to meet their requirements for the fish. Olive flounder (initial average weight, 96.8±0.2 g) were randomly distributed into 20 tanks (425 L each) at a density of 25 fish per tank. Four replicate groups of fish were fed one of the diets two times daily for 15 weeks. At the end of the feeding trial, no significant differences were found among all the fish groups in growth performance, feed utilization, nonspecific immune responses and hematological health parameters. Thus, this result indicates that the plant proteins with the three limiting amino acids could replace FM up to 40% in diets for growing olive flounder.

• Fisheries and Aquatic Sciences
• /
• v.18 no.2
• /
• pp.143-149
• /
• 2015

This experiment was conducted to evaluate the synergistic effects of vitamin C and E on methylmercury (MeHg) toxicity in juvenile olive flounder Paralichthys olivaceus. In a $3{\times}3$ factorial design, 9 experimental diets containing three different vitamin C (0, 200 or 400 mg/kg diet in the form of l-ascorbyl-2-monophosphate) and vitamin E (0, 100 or 200 mg/kg diet in the form of dl-${\alpha}$-tocopheryl acetate) levels with the Hg toxicity level (20 mg/kg diet in the form of MeHg) were formulated. Triplicate groups of fish averaging $2.3{\pm}0.05g(mean{\pm}SD)$ were fed one of the 9 diets in a flow through system for 8 weeks. Fish fed 400 mg vitamin C/kg diet with 100 or 200 mg vitamin E/kg diet showed significantly (P < 0.05) higher weight gain (WG) than did fish fed the other diets. Fish fed 400 mg vitamin C/kg diet at all vitamin E levels and those which fed vitamin C and E equally at a rate of 200 mg/kg diet showed significantly (P < 0.05) higher feed efficiency (FE), specific growth rate (SGR) and protein efficiency ratio (PER) than did fish fed the other diets. Fish fed 200 and 400 mg vitamin C/kg diet exhibited significantly (P < 0.05) lower Hg concentration in their muscle as well as kidney than did fish fed the other diets. Therefore, these results clearly indicated that the synergistic effects of these two vitamins on MeHg toxicity by supplementing dietary vitamin C (200 and 400 mg/kg diet) with vitamin E (100 and 200 mg/kg diet) in juvenile olive flounder.

• Korean Journal of Ichthyology
• /
• v.24 no.1
• /
• pp.11-19
• /
• 2012

Seasonal fish species composition in the sandy shore adjacent to eelgrass bed was determined. Monthly samples were collected by a beam trawl from August 2009 to July 2010. A total of 38 species, 1,232 individuals and 5,277.7g of fishes were collected. The dominant species were $Favonigobius$ $gymnauchen$, $Takifugu$ $niphobles$, $Hypodytes$ $rubripinnis$, and $Rudarius$ $ercodes$. These four dominant fish accounted for 73.2% of the total number of individuals, and 53.9% of the biomass of collected fish. During the survey, the water temperature ranged from 11 to $25^{\circ}C$, and the salinity ranged from 29 to 35 psu. The monthly species diversity index showed the lowest value of 0.89 in March and highest value of 2.35 in June 2010. Fish species composition and abundance in Myeongsa sandy shore, were similar to that the adjacent eelgrass bed, but were different from those of Gujora sandy shore open the sea.

• Fisheries and Aquatic Sciences
• /
• v.7 no.1
• /
• pp.1-9
• /
• 2004

Sweet smelt (Plecoglossus altivelis) were fed four different diets supplemented with either perilla oil $(2.0\%)$ rich in 18:3n-3 (CP), and perilla oil and Enteromorpha compressa meal $(2.0\%)$ (CPA), soybean oil rich in 18:2n-6 (CO), or soybean oil and algal meal (CA) for 4 weeks. The growth performance, fatty acid composition of muscle, plasma lipid peroxidation and blood components of the sweet smelt were then determined. The specific growth rate and feed efficiency in the fish fed the CPA diet were the highest, while the other groups showed similar results. The fatty acid composition of muscle in sweet smelt reflected the dietary lipids; 18:3n-3 was higher in the fish fed the CP and CPA diets, and 18:2n-6 was higher in the fish fed the CO and CA diets. The other fatty acid profiles presented almost no differences with respect to the diet composition. The fish fed the CA, CP and CPA diets contained significantly lower levels of triglyceride, thiobarbituric acid-reactive substances and hydroxyl radical in their plasma than that fed the CO diet. Phagocytic activity was the highest in the fish fed the CPA diet and higher in those of the fish fed the CP and CA diets compared to the CO diet group. The results from this study suggest that a dietary supplement of $2.0\%$ perilla oil together with $2.0\%$ E. compressa meal may improve the growth and health of cultured sweet smelt.

• Journal of fish pathology
• /
• v.28 no.2
• /
• pp.99-107
• /
• 2015

Despite its economic importance as an aquaculture species, the molecular and genetic information regarding physiologically important elements in rock bream (Oplegnathus fasciatus) is not completely understood. Rab proteins play a vital role in cellular mechanisms and immunity as one of the key regulators of membrane trafficking. In this investigation, a Rab gene, named as RbRab-5C-like, was identified from Oplegnathus fasciatus. RbRab-5C-like protein exhibited high homology with Rab proteins of other species and possessed signature characteristics of Rab proteins with four conserved cysteine residues. Phylogenetic analysis showed that RbRab-5C-like clustered with other fish counterparts. The RbRab-5C-like genomic sequence possesses six exons and five introns. Transcriptional analysis revealed that RbRab-5C-like was ubiquitously expressed in all examined tissues with the highest expression occurring in the liver. While the structural and homologic characteristics of RbRab-5C-like suggest a strong conservation of this element in different species, its mRNA distribution implies a wide range of biological significance in rock bream.

• Journal of Marine Bioscience and Biotechnology
• /
• v.2 no.1
• /
• pp.23-33
• /
• 2007

The constraints of traditional fish drying in Bangladesh have been reviewed and an effective solar fish dryer was developed with the small-scale processors and fishermen using locally available cheaper materials in order to dry fish in coastal region. After successful field testing, new solar dryer was demonstrated within the community in 3 different locations of Cox's Bazar for several batches of operations in each location from late September to March and found very effective in terms of architectural suitability, operational feasibility, technical efficiency, out-put quality (good texture, colour, flavour and long storage time), user's acceptability, commercial viability and environmental adequacy. A simple cost-profit analysis was done with the community operated products, which indicates that the new solar fish dryers could be operated profitably in coastal regions where sun-light and air flows are abundant.