• The Journal of Fisheries Business Administration
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• v.35 no.1
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• pp.1-22
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• 2004

Since the red grouper stock was initially declared to be overfished by the NMFS in September 2002, the Gulf of Mexico Fishery Management Council must prepare for the red grouper rebuilding plan considering the following alternative management policies: Total Allowable Catch(TAC), 5 - month season closure, 1800 - pound trip limit, and 50 - fathom longline boundary. The first concern the Council has is to evaluate the effects of recommended policies and the second is to analyze the impact of management policies on yellow edge grouper. This is because the fleets harvest red grouper also catch yellowedge grouper, the regulations on red grouper are likely to allow fishing effort to be distributed into yellowedge grouper. Therefore, this study is aimed at evaluating the biological and economic effects of management policies considering simultaneously the impact of red grouper regulations on yellow edge grouper by developing a combined red grouper and yellowedge grouper bioeconomic model. The overall results indicate that management policies for red grouper would adversely affect the yellowedge grouper stock if yellowedge grouper is not protected by its regulations. The TAC policy has the most serious impact on the yellowedge grouper stock, while the 1800 - pound trip limit policy minimizes the reduction in the yellowedge grouper stock. However, the target stock size of red grouper is achieved as well as the largest net present value of returns is gained in the TAC policy.

• Journal of fish pathology
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• v.34 no.1
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• pp.99-104
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• 2021

In this study, we investigated safety and efficacy of a low temperature immunization protocol with NNV in red spotted grouper, Epinephelus akaara and long tooth grouper, Epinephelus bruneus and seven band grouper, Hyporthodus septemfasciatus. Further, growth rate between immunized and naïve fish was evaluated during the experiment to check side effect of immunization. Three grouper species were immunized by immersion method with live NNV at 10^5.0 TCID₅₀/mL at 16.5℃ for 30 min and reared for 120 days at natural sea water temperature. To evaluate growth rate, total length and wet weight was measured 7 times after immunization. Immunized three grouper species were challenged by intramuscular inoculation with NNV at 10^4.2 TCID₅₀/100 µL/fish. Immunization at low temperature with live NNV did not show any clinical symptoms of infection, mortality and inhibition of growth. After challenge, cumulative mortality of naïve seven band grouper, red spotted grouper, long tooth grouper were 45, 10, 20 %, respectively. However no mortality was observed at immunized groupers. Thus, it was demonstrated that immunization at low temperature with live NNV are able to protect three different species of groupers without inhibition of growth.

• Development and Reproduction
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• v.20 no.2
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• pp.51-63
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• 2016

The landmark-based morphometric and meristic analysis of the kelp grouper (Epinephelus bruneus), red spotted grouper (E. akaara) and seven-banded grouper (E. septemfasciatus) were performed to compare the differentiation of overall body shape and structure. The measurements of the morphometric dimensions were observed in 25 parts (truss dimension: 16 parts; head part dimension: 9 parts) of 38 morphometric dimensions and also meristic differences observed in 3 parts (dorsal fin, anal fin and caudal fin) of 6 meristic counts (P < 0.05). Observed morphometric characteristics primarily involved in truss and head part dimension, kelp grouper have larger values in caudal part of truss dimension, kelp grouper, red spotted grouper and seven-banded grouper have similar values in pectoral part of truss dimension, in addition to, results of head part dimension showed that red spotted grouper have smaller values in overall dimensions (P < 0.05). As meristic characteristics, kelp grouper have more number of anal fin rays than other fish, red spotted grouper have more number of dorsal soft rays than other fish, and seven spotted grouper have more number of anal soft rays, and caudal fin rays than other fish (P < 0.05). Photographed under the x-ray, kelp grouper have the most curved vertebral column and largest swim bladder than other fishes (P < 0.05). Our results of this study confirmed that 3 subfamily fishes adequately can distinguish with external body shape, and we hope that the results of our study could be used to identify in Serranidae family as taxonomical parameters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.557-562
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• 2020

As part of an effort to establish of novel grouper hybrids for the aquaculture industry, we compared the embryonic development of fertilized eggs of giant grouper Epinephelus lanceolatus ♀×kelp grouper E. bruneus ♂ (GGKG) and giant grouper ♀×red-spotted grouper E. akaara ♂ (GGRG) with a maternal purebred (giant grouper ♀×♂, GG) at 27-29℃. The hatching rates were lower in GGKG (2.59%) and GGRG (0.36%) than in GG (12.29%). The hatching times were considerably longer in the two hybrids than in GG (22 h), which were similar between GGKG (28 h 30 min) and GGRG (28 h). The total lengths of yolk-absorbed larvae of GGKG (2.546±0.132 mm) and GGRG (2.602±0.093 mm) were similar to that of GG (2.565±0.149 mm). The deformity rates of hatched larvae (64.29-75.00%) did not differ between the two hybrids and GG. Although the hatching and deformity rates of GGKG and GGRG were inferior to those of GG, the possibility of mass production of the two hybrids larvae was demonstrated in this study.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.479-485
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• 2020

We evaluated the hatchability of fertilized eggs from six hybrid combinations of highly valued grouper species inhabiting temperate and warm waters, with the goal of establishing a novel hybrid with enhanced growth and viability during the culturing period in the temperate waters of Korea. Hybrid combinations with red-spotted grouper females exhibited high hatchability with high a fertilization and hatching rate of fertilized eggs and a low deformity rate of hatched larvae. Conversely, hybrid combinations with kelp grouper females had very low hatching rates and very high deformity rates; commercial production of seed from such crosses would be difficult without improving hatchability. The hatchabilities of convict grouper ♀×giant grouper ♂ and kelp grouper ♀×red-spotted grouper ♂ were lower than those of maternal purebreds, but these two hybrid combinations were expected to produce potentially large quantities of hatched larvae. In the above evaluation, promising hybrid combinations were identified for commercial production of seed. For these hybrids to contribute to the development of Korea's mariculture industry, mass production of fertilized eggs and seeds is necessary, along with the development of advanced rearing techniques, such as the identification of a suitable rearing temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.426-433
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• 2021

This study aimed to determine the appropriate salinity condition for optimal cultivation of the juvenile hybrid grouper Epinephleus akaara♀×E. lanceolatus♂ in conditions of decreasing salinity. The survival, growth, metabolic rate, stress, and histological response were investigated in juvenile hybrid grouper exposed to different salinities for 30 days. At 0 psu, the survival rate of the juvenile hybrid grouper was 60% on the 2nd day of exposure and all individuals died on the 3rd day of exposure. At salinities above 3 psu, all animals survived throughout the exposure period. Growth rate for body weight of the juvenile hybrid grouper was the highest in the control and the lowest at 10 psu. Plasma osmolality of the juvenile hybrid grouper exposed to different salinities was 313-355 mg Osmol/kg at salinities above 10 psu, and then decreased to 225-264 mg Osmol/kg at salinities below 5 psu. The oxygen consumption rate tended to decrease as the salinity decreased. Stress responses of the juvenile hybrid grouper were analyzed with decreasing salinity. Therefore, it is considered that a salinity of more than 20 psu is suitable for the culture of the juvenile hybrid grouper.

• Ocean and Polar Research
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• v.42 no.4
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• pp.303-311
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• 2020

In this study, the embryonic development and hatchability of eggs fertilized by the reciprocal hybrids of kelp grouper (Epinephelus bruneus) and red-spotted grouper (E. akaara) were evaluated with the goal of establishing a novel hybrid with enhanced growth and viability during the farming period in the temperate waters of Korea. The fertilization rates were lower for hybrids than for maternal purebreds and were significantly higher in the red-spotted grouper ♀ × kelp grouper ♂ hybrid (RGKG, 89.61 ± 1.58%) than in the kelp grouper ♀ × red-spotted grouper ♂ hybrid (KGRG, 74.82 ± 4.23%, p < 0.05). Unlike the fertilization rates, the hatching rates of fertilized eggs were similar between hybrids and maternal purebreds and did not differ significantly between KGRG and RGKG (72.74 ± 3.60% vs. 75.23 ± 2.20%, respectively, p > 0.05). The embryonic development of the hybrids was similar to that of maternal purebreds; however, irregular cleavage and asymmetric blastoderm were noticeable in the developing eggs of KGRG hybrids. The deformity rates of newly hatched larvae were higher in hybrids than in maternal purebreds and were significantly higher in KGRG than in RGKG (17.47 ± 1.28% vs. 7.11 ± 0.54%, respectively, p < 0.05). These results demonstrate the potential to produce viable larvae from these two hybrids. Although the production efficiency of KGRG was lower than that of RGKG, the fertilization, hatching, and deformity rates make both hybrids useful for further comparative studies regarding economic aspects.

• Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.346-355
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• 2024

Groupers are economically important species in the fishery and aquaculture industries in Asian countries. Various species of grouper, including hybrids, have been brought to market even without precise species identification. In this study, we analyzed the structure and expression profile of the gene encoding prolactin (PRL) in the red-spotted grouper Epinephelus akaara based on genomic DNA and cDNA templates. The results showed that the PRL gene consists of five exons encoding an open reading frame of 212 amino acids, including a putative signal peptide of 24 amino acids and a mature structural protein of 188 amino acids. It showed amino acid identities of 99% with Epinephelus coioides, 83% with Amphiprion melanopus, 82% with Acanthopagrus schlegelii, 75% with Oreochromis niloticus, 70% with Coregonus autumnalis, and 67% with Oncorhynchus mykiss, indicating its closer similarity to E. coioides and other groupers but marked distinction from non-teleost PRLs. PRL mRNA expression was detected mostly in the brain, including the pituitary gland, with little expression in other tissues. While the 5-exon structure of the PRL gene of red-spotted grouper and the exon sizes were conserved, the sizes of the introns, particularly the first intron, were markedly different among the grouper species. To examine whether these differences can be used to distinguish groupers of similar phenotypes, exon-primed intron-crossing analysis was carried out for various commercially important grouper species. The results showed clear differences in size of the amplified fragment encompassing the first intron of the PRL gene, indicating that this method could be used to develop species-specific markers capable of discriminating between grouper species and their hybrids at the molecular level.

• Development and Reproduction
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• v.16 no.3
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• pp.185-193
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• 2012

For the gonadal sex management of younger longtooth grouper (Epinephelus bruneus), this work investigated the timing and histological process of ovary differentiation and oocyte development of longtooth grouper larvae and juvenile. Specimens (from 1 to 365 DAH) were collected for gonadal histological study from June 2008 to August 2009. Rearing water temperature was ranged from 20 to $24^{\circ}C$. The primordial germ cells could be observed from 10 to 15 DAH, while undifferentiated gonad occurs from 20 to 50 DAH in longtooth grouper. The initial ovarian phase was 60 to 110 DAH with the formation of ovarian cavity and the increased in size of gonad. The ovarian phase started at 140 DAH with appearance of oogonia. The gonad at 365 DAH appeared to have full of oogonia and primary growth stage oocyte. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 60 DAH in longtooth grouper. The gonads in longtooth grouper differentiated directly into ovaries in all fish examined.

• Korean Journal of Ichthyology
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• v.27 no.1
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• pp.16-20
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• 2015

The hatchability of the artificially induced hybrid between two groupers (family Serranidae), red spotted grouper (Epinephelus akaara) and brown-marbled grouper (E. fuscoguttatus) that lives in different habit environment was investigated. There was no difference in the required time of each developmental stages after fertilization between hybrid (red spotted grouper ♀ ${\times}$ brown-marbled grouper ♂) and purebred (red spotted grouper ♀${\times}$♂) and required 25.6 hours to hatch at incubated in $25^{\circ}C$, but a noticeable unequal cleavage in cell size was observed in hybrid eggs unlikely to purebred. The hatching rate of fertilized eggs of hybrid was generally low across the four incubate temperatures (22, 25, 28, $31^{\circ}C$) with highest 9.8% in $25^{\circ}C$. This study demonstrated the possibility of artificial hybridization between two groupers, red spotted grouper and brown-marbled grouper, thus preparing the groundwork on developmental characteristics, deformities of hatched larvae and early survival ability for further studies on aquaculture.