• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.70-73
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• 2014

Interspecific hybrids between tiger grouper Epinephelus fuscoguttatus and giant grouper E. lanceolatus were genetically identified based on the partial sequence analysis of mitochondrial cytochrome c oxidase I (COX I) gene and nuclear recombination activating gene 2 (RAG 2) gene. Out of 585 base positions of RAG 2, a total of five nucleotide substitutions were detected between the two parental species (E. fuscoguttatus and E. lanceolatus). The hybrids had two distinct types of RAG 2 sequences corresponding to those of both parental species. Mitochondrial COX I gene sequencing showed that hybrids had sequences identical to E. fuscoguttatus. Molecular data clearly demonstrate that hybridization does occur between E. fuscoguttatus and E. lanceolatus, but with E. fuscoguttatus as the maternal parent.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.566-571
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• 2020

To classify a presumed hybrid of imported grouper species acquired from the National Fishery Products Quality Management Service, maternal and paternal lines were identified based on partial sequencing of mitochondrial cytochrome c oxidase 1 (co1) and nuclear recombination activation gene 1 (rag1) genes. The matrilineal species was identified as Epinephleus moara by a partial (760 bp) co1 sequence. Ambiguous sequences with base pairs belonging to E. moara or E. lanceolatus were found in a total of 15 different base pairs in the partial 1,159 bp of the rag1 gene, and the patrilineal species was found to be E. lanceolatus. Therefore, all of the groupers examined in the study were identified to be hybrids of E. moara and E. lanceolatus. In addition, a fast and convenient method using random amplification of polymorphic DNA (RAPD) was established for hybrid discrimination. Hybrids between E. moara ♀ and E. lanceolatus ♂ were identified through specific bands of 387 bp and 433 bp in PRIMER 6.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.2
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• pp.129-136
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• 2022

The nutrient composition of the muscle of the hybrid grouper (Epinephelus fuscoguttatus×E. lanceolatus, HG) and the hybrid longtooth grouper (E. moara×E. lanceolatus, HLG) was measured as a function of body weight in this study. The crude protein and lipid levels in HG were 21.0-21.2 g/100 g and 1.9-3.4 g/100 g, respectively. HLG contained 20.6-20.7 g/100 g protein, and 3.9-5.5 g/100 g crude lipid. The total amino acid contents of HG were 18,829.7-18,980.2 mg/100 g and that of HLG was 17,793.7-19,293.7 mg/100 g. The mean saturated fatty acid content was 0.61-1.09 g/100 g for HG and 1.27-1.77 g/100 g for HLG. Monounsaturated and polyunsaturated fatty acid levels were 0.59-1.02 g/100 g (Monoene), 0.67-1.11 g/100 g (Polyene) in HG, which were lower than the 1.21-1.78 (Monoene), 1.22-1.69 g/100 g (Polyene) found in HLG. The highest mineral content (K and P) of HG was 510.13-517.05 mg/100g and 231.59-247.67 mg/100 g, while that of HLG was 518.81-523.59 mg/100 g and 257.51-248.84 mg/100 g, respectively. In conclusion, there is potential for expanding the commercial utilization of HG and HLG as food resources as they are both nutrient-rich.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.572-576
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• 2020

As grouper aquaculture production intensifies worldwide, hybrids are increasingly produced to induce heterosis of traits such as rapid growth and strong environmental adaptability. In this study, we compared the morphological characteristics of a hybrid grouper to those of its parent species Epinephelus moara and E. lanceolatus. The coefficients of external and skeletal traits evaluated using soft X-rays did not differ significantly among groups; however, several patterns were detected among measured traits. The body depth (BD), length of caudal peduncle (LCP), and pre-anal fin length (PAL) of the hybrid were the same as those of E. moara, whereas the pre-pectoral fin length (PPL) and interorbital width (IOW) of the hybrid were the same as those of E. lanceolatus. Traits that did not differ significantly among the three groups included pre-dorsal fin length (PDL), pre-ventral fin length (PVL), length of anal fin (LAF), and length of dorsal fin (LDF), whereas the depth of caudal peduncle (DCP) and snout length (SNL) showed intermediate traits, and eye diameter (ED) was significantly smaller in the hybrid. Therefore, intermediate traits such as DCP and SNL and specific traits such as ED may be used as indices for hybrid classification.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.612-619
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• 2016

In this study, we crossbred Epinephelus akaara and E. lanceolatus to produce a hybrid grouper with faster growth and adaptation to domestic aquaculture environments. The plasma cortisol and glucose levels and osmoregulation (stress response indicators) of the hybrid grouper, E. akaara ♀ × E. lanceolatus ♂, were investigated under several salinity levels (32, 24, 16, and 8 psu). The body lengths and weights of E. akaara (8.2 ± 0.1 cm, 8.3 ± 0.4 g) and the hybrid (8.6 ± 0.1 cm, 10.0 ± 0.4 g) were similar at the start of the experiment, but were significantly different at the end of the experiment. Juveniles of both E. akaara and the hybrid showed greater weight gain, specific growth, and feed conversion rate (FCR) under low salinity of 16 psu. Under the 8 psu treatment, the juvenile E. akaara all died, while the hybrid juveniles survived. Plasma cortisol levels were not affected by lower salinity in both species. The above results indicate that the hybrid is more tolerant of low salinity than is E. akaara, although both species exhibited higher growth and FCR at 16 psu, lower than the salinity of natural seawater. Thus, juveniles of both E. akaara and the hybrid can be more effectively cultured in brackish areas or waters with salinity lower than that of seawater.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.235-240
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• 2019

The anaesthetic effect of tricaine methanesulfonate (MS-222) concentrations and water temperatures for longtooth grouper (Epinephelus moara) and hybrid grouper (E. moara ♀ × E. lanceolatus ♂) were investigated. Anesthetic induction and recovery time were measured at 18, 22, 26 and 30℃ of Cwater temperature and 100, 150, 200 and 250 ppm of anesthetic concentrations. Anesthetic induction time tended to decrease with increasing concentration and water temperature. Recovery time was proportional to concentration, but inversely proportional to water temperature. However, there was no significant differences in recovery time at 22℃ or lower. The optimal anesthesia condition was 30℃ and 100 ppm, which was the shortest recovery time for longtooth grouper, and 150 ppm at 30℃ in the case of hybrid grouper because anesthetic time is significantly different with 100 ppm in spite of no significant differences with 100 ppm for recovery time. As a results of two-way ANOVA test, there was a significant difference between the species of longtooth and hybrid grouper. On the other hand, there was no interaction effect between concentration and species. Also, there was no interaction effect among species, concentration, and water temperature.

• Ocean and Polar Research
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• v.40 no.3
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• pp.161-167
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• 2018

We examined the effect of salinity and water temperature on hatching and survival rates of fertilized eggs of hybrid grouper (Epinephelus fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) at different developmental stages, determining optimal conditions for their long-distance transportation. Deformities and hatching rates of fertilized grouper eggs were observed at salinities of 24, 27, 30, 33, 36, and 39 psu. The optimal salinity was determined to be 36 psu, with a survival rate of $70.0{\pm}2.0%$. Transportation experiments at 36 psu were conducted at water temperatures of 21, 24, 27, and $30^{\circ}C$, different developmental stages such as morula, 5-myomere, and tail beating for hatching and survival rates. The optimal water temperature and developmental stage for transporatation were $30^{\circ}C$ and tail beating stage and those hatching rates were $50.6{\pm}1.9%$ and $86.3{\pm}1.3%$, respectively. At $21^{\circ}C$, the survival rate by transportation water temperature was highest ($73.1{\pm}10.6%$), but the hatching rate ($17.1{\pm}3.1%$) was lowest. Therefore, the hybrid grouper fertilized eggs (E. fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) can be most efficiently produced under long-distance transportation conditions during the tail beating stage and at a water temperature of $30^{\circ}C$.

• 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.

• Journal of Veterinary Clinics
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• v.27 no.5
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• pp.618-621
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• 2010

A giant grouper (Epinephelus lanceolatus) that was reared for public exhibition in a private commercial aquarium in Seoul, Korea, was recently found dead. The fish had evidenced symptoms including anorexia, lethargy, and depression persisting for two weeks. A bacterial pathogen from fish organs (kidney, liver, spleen) was cultured, identified and confirmed as Photobacterium damselae subsp. damselae, using a Vitek System 2, API 20E test, multiplex PCR, and 16S rRNA gene sequencing. In this paper, we have described the isolation and identification of Photobacterium damselae subsp. damselae from a giant grouper reared in a private aquarium in Korea.

• Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.298-310
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• 2022

Although giant and large fish species are highly important as a keystone species in the marine ecosystem, there have been no or few studies on their spatio-temporal variations around the Korean peninsula. For this, we analyzed daily reports made by observers at 57 fishery landing sites in Korea over 6 years, from 2011 to 2016. In total, 153 fish species were re-identified based on photos and descriptions recorded by Korean observers, of which five species were classified as a giant fish over 5 m in maximum total length (MTL) and 17 species as a large fish from 3 m to 5 m MTL according to the data presented by Froese & Pauly (2021). Among the giant and large fish species, Mola mola was the most abundant species, with 75 individuals landed as by-catch. The second most abundant species was Isurus oxyrinchus (31), followed by Mobula mobular (23), Lamna ditropis (17), Masturus lanceolatus (16), Sphyrna zygaena (14), and Prionace glauca (12). As a result of cluster analysis based on the number of individuals of giant and large fish species by year and sea, six years were separated into two clusters (2011-2013 vs. 2014-2016), with high contribution of M. mola, I. oxyrinchus, and M. lanceolatus; and three seas were separated into two clusters (eastern + southern seas vs. western sea), with high contribution of M. lanceolatus, L. ditropis, and I. oxyrinchus. The largest number of M. mola accounted for 64% of the total in 2014 and 2016, and 71% in summer (June-August). It is assumed to have a correlation between seawater temperature fluctuation and the occurrence of giant and large fish species. Our study highlights importance of longterm monitoring of giant and large fish species, and can help to understand the life cycle such as natal or nursery migration of giant and large fish species around the Korean peninsula.