• Development and Reproduction
• /
• v.17 no.4
• /
• pp.369-377
• /
• 2013

The fertilized eggs of E. septemfasciatus are spherical and transparent with buoyancy at 790 to $890{\mu}m$ (average $821.8{\pm}2.0{\mu}m$) in diameter with 170 to $230{\mu}m$ oil globules (average $192.9{\pm}0.93{\mu}m$). Hatching began approximately 46 and 35 hours after fertilization at $22.0^{\circ}C$ and $25.0^{\circ}C$ water temperature, respectively. The average total length of newly hatched larvae was $1.75{\pm}0.03mm$. Most of the yolk and oil globules were absorbed within 3 to 4 days after hatching. The larvae reached 2.48 to 2.72 mm in total length, and their mouths and anuses opened at 3 to 4 days after hatching. In this time, the mouth diameters of the larvae were 0.209 to 0.238 mm. The larvae reached 3.24 to 4.15 mm in total length at 11 to 17 days after hatching, and began to metamorphose at the time the second dorsal and pelvic spines appeared and elongated. The abdominal cavity was densely lined with melanophores. The larvae reached 5.12 mm in total length at 24 days after hatching.

• Development and Reproduction
• /
• v.20 no.3
• /
• pp.187-196
• /
• 2016

The objective of the current study was to determine acute plasma stress responses in two size groups of juvenile Epinephelus akaara (average body weight: $8.4{\pm}2.1$ and $3.3{\pm}0.6g$; 150 and 120 days after hatch, respectively) exposed to abrupt salinity drops (from 34 practical salinity unit, PSU seawater to 18, 10 PSU (experiment 1) or 26, 18, 10 PSU (experiment 2), respectively). Plasma glucose, glutamic oxalate transaminase, glutamic pyruvate transaminase, red blood cell counts, and gill histology were determined during 72 h exposure. Significantly increased plasma glucose, glutamic oxalate transaminase levels, and red blood cell counts were observed in fish exposed to 18 or 10 PSU. Histological changes, such as hyperplasia and lifting of epithelium in the gill secondary lamellae, were also observed in fish exposed to 18 or 10 PSU at 72 h post-drop. E. akaara exposed to sudden salinity drops to 18 or 10 PSU still seems to undergo the primary adjustment phase before fish reaches a new homeostasis, whereas fish exposed to 26 PSU seems to mount osmotic changes. Therefore, the no observed adverse effect levels for 72 h acute salinity challenge was 26 PSU in our study, and salinity drop to 18 PSU and below can possibly cause acute adverse effect, in which fish could be vulnerable to additional stresses such as a temperature changes or handling stress.

• Development and Reproduction
• /
• v.20 no.1
• /
• pp.31-40
• /
• 2016

This study was conducted in order to examine the egg development in red spotted grouper, Epinephelus akaara and the morphological development of its larvae and juveniles, and to obtain data for taxonomic research. This study was conducted in June 2013, and 50 male and female fish were used for the study. One hundred ${\mu}g/kg$ of LHRHa was injected into the body of the fish for inducing spawning, and the fish were kept in a small-sized fish holder ($2{\times}2{\times}2m$). Eggs were colorless transparent free pelagic eggs, 0.71-0.77 mm large (mean $0.74{\pm}0.02mm$, n=30), and had an oil globule. Hatching started within 27 h after fertilization. Pre-larvae that emerged just after hatching were 2.02-2.17 mm in total length (mean $2.10{\pm}0.11mm$), their mouth and anus were not opened yet, and the whole body was covered with a membrane fin. Post-larvae that emerged 15 days post hatching were 3.88-4.07 mm in total length (mean $3.98{\pm}0.13mm$), and had a ventral fin with two rays and a caudal fin with eight rays. Juveniles that were formed at 55 d post hatching, were 31.9-35.2 mm in total length (mean $33.6{\pm}2.33mm$), with red color deposited over the entire body, and black chromophores deposited in a spotted pattern. The number of fin rays, body color, and shape were the same as that in the adult fish.

• Development and Reproduction
• /
• v.18 no.1
• /
• pp.13-23
• /
• 2014

This study is conducted to monitor the morphological developmental features of the egg development, larvae and juvenile of Epinephelus septemfasciatus, the fertilized eggs were gotton using artificial insemination. Matured parents are collected from marine caged fish farms in Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanamdo Korea in June 2012. The fertilized eggs were pelagic eggs containing one oil globule, and measured 0.81~0.89 mm ($0.85{\pm}0.04mm$, n=50) in diameter. In regard to rearing environment, the water temperature is $21.0{\sim}23.0^{\circ}C$ and the salinity is 32.0~33.2‰. Hatching was observed from 48 hours after fertilization, the mouth and anus of prelarvae was not opened but had egg yolk at newly hatched. 4 days after hatching, the mouth and anus of postlarvae was opened and began to eat Rotifer and was measured 2.40~2.49 mm ($2.45{\pm}0.03mm$ n=10) in total length. 12 days after hatching, postlarvae was measured 3.77~4.67 mm ($4.27{\pm}0.33mm$) in total length, its the second pole tide of dorsal fin and the first pole tide of pelvic fin was extended longitudinally. 71 days after hatching, juvenile was measured 40.5~45.4 mm ($42.6{\pm}2.04mm$) in total length. Seven bands were observed in body, and pole tides of dorsal and pelvic fins were shortened.

• Development and Reproduction
• /
• v.21 no.4
• /
• pp.457-466
• /
• 2017

Survival of embryos largely depends on yolk processing during early development. Proteolytic enzymes, cathepsin B & D (ctsb & ctsd) are known to have some important roles in yolk processing of various fish species. Mature female red spotted groupers were injected with human chorionic gonadotropin (HCG) to induce ovulation. The fertilized eggs and embryos were sampled at 0, 4 and 24 HPF (hours post fertilization). Survivals of each groups of embryos were checked at 24 and 48 HPH (hours post hatching). Transcripts of ctsb & ctsd showed the highest level at 0 HPF and relatively high at 4 HPF, but greatly decreased at 24 HPF. In bad egg quality group (BE, embryos survived until 24 HPH), transcript level of ctsb at 4 HPF were significantly lower than the transcript level at the same stage in good egg quality group (GE, embryos survived until 48 HPH) while no significant change of ctsb transcript level was observed at 0 or 24 HPF between BE and GE. Transcript level of ctsd was decreased at 24 HPF, but the difference was not as strong as the case of ctsb transcript. These results suggest that maternal ctsb transcript rather than ctsd transcript is likely to be involved in egg quality resulting in the difference of survival rate of embryos at early developmental period in this species.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.2
• /
• pp.526-536
• /
• 2015

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp. I) as control, decrease in the manners of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu (Exp. II), $35{\rightarrow}10{\rightarrow}0$ psu (Exp. III) and $35{\rightarrow}0$ psu (Exp. IV). The average oxygen consumption at $27^{\circ}C$ in Exp. I (control) was $106.9{\pm}0.7mg$ $O_2/kg/h$. In Exp. II, according to the changes of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu in freshwater acclimation, fish showed the gradual decrease in oxygen consumption as $108.1{\pm}2.1$, $99.6{\pm}2.9$, $74.6{\pm}0.9$ and $62.7{\pm}1.0mg$ $O_2/kg/h$, respectively. The fish in Exp. III also revealed the same tendency as $106.5{\pm}1.3$, $77.0{\pm}1.2$ and $64.7{\pm}1.2mg$ $O_2/kg/h$, respectively. In Exp. IV, fish showed the decreased oxygen consumption from $109.0{\pm}0.9mg$ $O_2/kg/h$ of 35 psu to $71.6{\pm}2.0mg$ $O_2/kg/h$ of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• Journal of Aquaculture
• /
• v.11 no.2
• /
• pp.173-182
• /
• 1998

The study has been conducted to understand gonadal development and the effects of $17^{\alpha}$-methyltestosterone on sex inversion of the red spotted grouper, Epinephelus akaara. Fish were collected from Deukyand bay in the southern coast of Korea in August, 1996 and then they had been cultivated at the indoor tank until August, 1997. Gonad somatic index (GSI) in the females of both treated and control group began to increase from February when water temperature was rainse again, and reached the maximum value in August, whereas it had decreased from September adn thereafter maintained relatively low value until January. Unlike females, GSI in the male or intersex of treated groups decreased after June. Hepatosomatic index (HSI) of the control group tended to show the relatively low around Autumn, whereas it showed relatively highr value in April and June when the ovary was in the growing stage. Although the treated groups showed relatively higher value of the HSI than the control, hte paterns in monthly variation of HSI were similar to the control. Sexual change of the female grouper to the male was attempted by acceleration with oral administration of $17^{\alpha}$-methyltestosterone at the dose of 0.2 and 0.5mg/kg fish for 120days. Transitional hermaphroditic gonads were observed from the various size of groupers ranging 21.0 to 36.1 cm in total length, while the functional males could be induced from th individuals of 28.8 to 33.5cm in total length. This result indicated that larger groupers than 30cm in total length should be used for sex inversion to maleness with $17^{\alpha}$-methyltestosterone.

• Journal of Aquaculture
• /
• v.11 no.4
• /
• pp.573-580
• /
• 1998

Red spotted grouper, Epinephelus akaara is distributed in the south and west coasts of Korea. The natural stocks of the fish are decreasing sharply year by uear because of reckless overfishing. This research was carried out to understand general informations on maturation, sex composition and sex-reversals of the fish. Annual fishing uields of red spotted grouper in the castal area of Byonsan Peninsular of Kora decreased over 10% from 1992 to 1994. The main fishing season was from May to July with fishing gear of Hand-lines. Gonadosomatic index (GSI) and condition factor were highest on early and late July, respectively, thus main spawning reriod was assumed from late July to early August. The relationship between total length (X) and body weight (Y) for wild adults was represented as a regression, Y=$0.0169X^{2.9705}$, ($r^2$=0.96). Frequency of sex of wild red spotted gouper showed that the number of female below 38cm in total length was more than that of male, and hermaphrodite mainly occurred from 28cm to 32cm in total length the frequency of male and female were almost same. Also hermaphrodite occurred mainly between 25~29cm. Sex reversal ration of the adults reared in a tank for a year with different sexual compositions revealted that the frequency of female reversed from male was more than that of male reversed from female at 1:1 and 1:2 stocking densities of female and male, respectively. Also, about 20% of female was reversed to male when all females were reared. And the size of the fish reversed to male was larger than that of non-reversed female.

• Korean Journal of Ichthyology
• /
• v.26 no.4
• /
• pp.259-266
• /
• 2014

This study investigated the effects of water temperature and photoperiod on oxygen consumption (OC) in the giant grouper Epinephelus lanceolatus. OC rate in the giant grouper at 17, 22, 27 and $32^{\circ}C$ were $61.7{\pm}0.4$, $72.2{\pm}0.6$, $102.9{\pm}0.8$ and $141.7{\pm}1.0mg\;O_2/kg/h$, respectively, indicating a linear increase in OC with water temperature. Photoperiod was regulated in accordance with the light (06:00~18:00 h, L) and dark (18:00~06:00 h, D) phases of the diel cycle (12L/12D), with a water temperature of at 17, 22, 27 and $32^{\circ}C$. OC rates during the light and dark phases were $62.7{\pm}0.4$, $62.5{\pm}0.3mg\;O_2/kg/h$, respectively, at $17^{\circ}C$. No significant differences were observed between the light and dark phases (P>0.05). OC raters during the light and dark phases were $74.8{\pm}0.7$, $69.6{\pm}0.6mg\;O_2/kg/h$ at $22^{\circ}C$, $107{\pm}1.2$, $98.0{\pm}0.7mg\;O_2/kg/h$ at $27^{\circ}C$ and $147.6{\pm}1.1$, $135.8{\pm}0.8mg\;O_2/kg/h$ at $32^{\circ}C$, respectively, indicating that OC is higher during daylight than nighttime. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• Fisheries and Aquatic Sciences
• /
• v.16 no.1
• /
• pp.49-52
• /
• 2013

A single specimen of Epinephelus lanceolatus, belonging to Epinephelinae of the family Serranidae, was newly collected from Jeju Island, South Korea, in December 2009. Epinephelus lanceolatus is characterized by anterior lateral-line scales with branched tubules, cycloid scales, irregular white spots, and fins with numerous small black spots. We propose a Korean name, "Dae-wang-ba-ri' for this species.