• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.54-61
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• 2017

We investigate predation rates of larvae and juveniles of Rana catesbeiana by using six native predatory fishes and six birds to select effective species to ecological control and management of R. catesbeiana that is invasive alien species and affects seriously wetland in Korea. Among freshwater fishes, Pseudobagrus fulvidraco, Silurus asotus and Channa argus ate larvae and juveniles of R. catesbeiana, and prefer the former, however Opsariichthys uncirostris, Monopterus albus and Anguilla japonica didn't eat at all. Six experimental water birds, Cygnus columbianus, Cygnus cygnus, Anas crecca, Aix galericulata, Anas penelope and Anas formosa nerver ate them. We were able to confirm control of R. catesbeiana probability using the native predatory fishes in Korea wetland.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.482-488
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• 2010

Three specimens of Cynoglossidae larvae were collected from the southern Korean Sea in May and August of 2009, and were identified using morphological and molecular analysis. Specimens were divided into two groups based on the number of elongated dorsal fin rays on the top of the head: Cynoglossidae sp. A was defined as having two elongated dorsal fin rays, while Cynoglossidae sp. B possessed a single elongated dorsal fin ray. One specimen of Cynoglossidae sp. A, a post-larva with a notochord length (NL) of 5.8 mm was thought to be a Cynoglossus joyneri larva based on the presence of 115 dorsal pterogiophores, 85 anal pterogiophores, and 50 myomeres. Two specimens of Cynoglossidae sp. B, a 4.1 mm NL larva and a 11.3 mm NL juvenile, were thought to be Cynoglossus abbreviatus based on the presence of yolk in the former and 133 dorsal fin rays, 105 anal fin rays, and 63 myomeres in the latter. To test this morphology-based identification, molecular analysis was conducted using 419-422 bp of mitochondrial DNA 16S rRNA. Cynoglossidae sp. A was clearly matched to a Cynoglossus joyneri adult (d=0.000) and Cynoglossidae sp. B clustered closely with Cynoglossus abbreviatus adults (d=0.002). A neighbor-joining tree supported this robust relationship (bootstrap value=100%). Therefore, these molecular data validate the morphological identification of the two Cynoglossidae larval species.

• Korean Journal of Ichthyology
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• v.10 no.1
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• pp.106-114
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• 1998

In order to estimate energy budget of the rockfish, Sebastes schlegeli juvenile, during the period from parturition to juvenile, of rockfish were reared at constant condition of water temperature($16^{\circ}C$ and $20^{\circ}C$). Energy used by the reared juveniles were calculated from estimates of data on growth, oxygen consumption, nitrogen excretion, feeding and energy content. After parturition, total length of juvenile was 4.56~5.49mm(average 4.97mm, n=20), and the average dally growth rates were 0.50mm at $20^{\circ}C$. The weight-specific oxygen consumption and nitrogen excretion rates decreased with increasing body weight. Temperature significantly affected oxygen consumption and nitrogen execretion rates, with the higher rates at $20^{\circ}C$ than $16^{\circ}C$. During the 25 days from parturition to jllveniles, feeding rates were 65.8cal at $16^{\circ}C$, and 89.2cal at $20^{\circ}C$. The assimilation effeciency estimated by nitrogen content of food and egested feces were 85.21% at $16^{\circ}C$ and $20^{\circ}C$. During the period from parturition to juvenile, energy was used the higher in body growth than in oxygen consumption. The gross growth efficiencies($K_1$)and net growth efficiencies($K_2$) of the rockfish, Sebastes schlegeli juvenile ranged from 43% to 47% and from 50% to 55%, respectively.

• Korean Journal of Ichthyology
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• v.21 no.4
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• pp.247-252
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• 2009

The egg development and early life history of the Korean endangered fish Koreocobitis naktongensis (Cobitidae) were investigated. Eggs from the females were obtained by injecting 10 IU/g of human chorionic gonadotropin and inseminated with sperm by the dry method in the laboratory. The fertilized eggs were 1.0~1.2 mm in diameter and had no oil globules. The embryo began to hatch about 38 hrs after fertilization under water temperature of $20{\pm}1^{\circ}C$. The newly-hatched larvae were 2.6~2.8 mm in total length, and their mouth and anus were not yet opened. Seven days after hatching, the postlarvae were 4.5~5.2 mm in total length, and their yolk sacs were completely absorbed. They entered the juvenile stage when all fin-rays were formed at 50 days after hatching, and their total lengths were 21~27 mm.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.41-46
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• 2016

The feeding habits of juvenile (14.0~29.0 mm SL) of Gymnogobius heptacanthus were examined based on 229 individuals, that collected from June to August 2011 in the coastal water of Geoje, Korea. G. heptacanthus fed mainly on copepods which constituted 96.74% in IRI. Barnacle larvae were the second largest dietary component. Its diet also included small quantities of tintinnids, cladocerans and decapods. Graphical analysis of the diet composition showed that G. heptacanthus is a specialized predator characterized by strong individual feeding specialization. Especially copepods were heavily selected by of juvenile G. heptacanthus regardless of prey availability.

• Korean Journal of Ichthyology
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• v.36 no.2
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• pp.120-128
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• 2024

In this study, the characteristics of the early life history were investigated for the Hypomesus nipponensis in the west coast Daeho Bay. Egg's were adhesive eggs that had the property of sinking in water in a circular shape. The size of mature eggs was 0.52~0.66 (average of 0.59±0.03, n=30) mm. The hatching time took 140 hours at a water temperature of 22~23℃. Immediately after hatching, the yolk sac larvae was 4.78~5.60 (average of 5.25±0.26, n=30) mm in total length, and the mouth and anus were not completely opened. On the 7 days after hatching, the preflexion larvae was 5.91~6.64 (6.32±0.21) mm in total length, and the mouth and anus were opened, and feeding activities were started. On the 25 days after hatching, the flexion larvae was 9.70~12.3 (10.2±0.63) mm in total length, and the end of the spine at the tail end began to bend upward. On the 42 days after hatching, the postflexion larvae was 14.1~18.8 (16.9±1.44) mm in total length, and the end of the spine at the tail was completely bent at 45°. On the 56 days after hatching, it reached the integer with 10 dorsal fins, 16 anal fins, 7 ventral fins, and 19 caudal fins. According to the study, there were spot-shaped melanophore vesicles under the pectoral fins during the incubation period, the different positions of the egg yolk compared to the battlefield, the deposition of melanophore vesicles on the back and under the body of the caudal part during the postflexion larvae period, and the absence of melanophore vesicles on the torso between the head and the starting point of the dorsal fin. It was distinguished from related species in that melanophore vesicles were deposited in one row from the back of the body to the caudal part during the juvenile period.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.177-183
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• 1999

This study was conducted to observe the spawning behavior and early life history of chinese minnow, Rhynchocypris oxycephalus reared in the laboratory. The spawning period of Rhynchocypris oxycephalus is from May to June in nature. The eggs of Rhynchocypris oxycephalus were spawned on the sand and surface of the gravel. The fertilization eggs were demersal in shape and adhesive, released as a clump forming a thin layer and their diameter were 1.70~1.90mm (mean 1.80 mm, n=20). Hatching of eggs was started in 88 hour 45 minute after fertilization at water temperature $19{\pm}0.5^{\circ}C$ and finished in 90 hour. Newly-hatched larvae were measured 4.87~5.02 mm in total length (TL, mean 4.94 mm), mouth and anus were not opened. 6 days old larvae were 6.32~6.56 mm in TL (mean 6.44 mm). Yolk sac was almost absorbed, mouth and anus was began to open. 13 days old larvae were 6.74~6.91 mm in TL (mean 6.82 mm). Part of Dorsal fin was began to rising and myomere number was 15+23=38. 25 days after hatching, total length of larvae was 8.45~8.60 mm (mean 8.52 mm). Dorsal and anal fin rays became differentiated, and also caudal part of the notocord flexion was achieved at $45^{\circ}C$. In the time, growth rate was higher than the other stage. Aggregate numbers of all fin rays were completed at 16.39~16.57 mm in TL (60 days after hatching), at which time the larvae reached the juvenile stage, but fin-fold on ventral was remained yet. External features of adult specimens were almost completed at 80 day old juveniles (18.69~18.87 mm in TL).

• Journal of Aquaculture
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• v.9 no.1
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• pp.43-55
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• 1996

The experiment was performed to evaluate the possibility of utilizing underground sea water for the seed production of tiger puffer, Takifugu rubripes. For this purpose, the effects of 6 different salinities (3.5, 7.0, 14.0, 20.0, 27.0, $33.0\%_{\circ}$) were determined based on the hatching rate of fertilized eggs, survival rate and the amount of food consumed by hatched larvae, where as the effects of 3 different salinities (20.0, 27.0, $33.0\%_{\circ}$) were also examined with rearing tiger puffer juvenile ($4.29{\pm}0.50$ cm in total length) for 50 days in the closed recirculating water system. As a results, either the hatching or the survival rate of more than $70.0\%$ were obtained from the fertilized eggs reared at the salinity of 27.0 to $33.0\%_{\circ}$, the early hatched larvae at 27.0 to $33.0\%_{\circ}$, and the 10-day-old larvae at 20 to $33.0\%_{\circ}$. At three different salinities, the survival rate of 20-day- and 30-day-old larvae turned out to be $89.0\%$ and $92.5\%$, respectively. The salinity for maximum food intake thus appeared to be from 27.0 to $33.0\%_{\circ}$. In this condition, 20-day-old hatched larvae consumed $323\~342$ Artemia nauplii and 30-day-old hatched larvae ate $1,559\~1,5791$ A. nauplii. The highest growth rate of fingerlings were observed at the salinity $27\%$ and followed by 33.0 and $20.0\%_{\circ}$, respectively. The relationship between the days of rearing (X) and the total length (Y) of the fingerlings were as follows : $33.0\%_{\circ}$ group : Y=0.107X-2.532 (r=0.982) $27.0\%_{\circ}$ group : Y=0.116X-3.195 (r=0.975) $20.0\%_{\circ}$ group : Y=0.116X-2.693 (r=0.987) The slopes of regression line estimated from $27.0\%_{\circ}$ and $33.0\%_{\circ}$ groups were significantly different from that of $20.0\%_{\circ}$ group.

• Journal of Aquaculture
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• v.11 no.1
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• pp.49-58
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• 1998

The spawning behavior and early life history of the Korean aucha perch, Coreoperca herzi were studied. The eggs were spawned in a one-layer mass, hanging from the underside of a largy stone and guarded by one male. According to the considerable size difference os eggs in the individual ovaries, it was concluded that they spawns several times within a spawning season of May~June. The ripe eggs were demersal and adhesive, and their diameter were 2.60~3.04mm with several oil globule of 0.10~0.64mm. Hatching in the tank with $19.0{\pm}1.0^{\circ}C.$ in men water temperature started from the 380 hours after fertilization. Newly-hatched larvae were measured 6.45~7.34mm in total length (TL, mean : 6.85mm), and mouth and anus were open. Melanophores were present on the head, around the yolk, and on the dorsal part of the abdominal region. 3 days old larvae were measured 7.00~7.40mm in TL (mean : 7.25mm), and they fed Daphnia sp. and Brachionus plicatilis actively. 6 days old larvae transformed to postlarval stage and they were 7.94~10.10mm in TL (mean : 9.00mm). As yolk sac were nearly absorbed, the caudal notochord flex at 45. Aggregate numbers of all fin rays were completed at over 16.90~19.80mm in TL (30 days after hatching), at which time the larvae reached the juvenile stage. In fifty days old larvae(24.60~27.10mm in TL) were similar in body form, lateral line and color to adult.

• Korean Journal of Ichthyology
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• v.27 no.3
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• pp.189-198
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• 2015

This research has been launched in order to observe the osteological development of sevenband grouper, Epinephelus septemfasciatus larvae and juveniles and will be used for the basic data of phylogenetically systematics research. We got some samples of larvae and juveniles from a adult fish which belongs to the sea cage in Geomun-do, Yeosu-si, Jeolla-namdo province, and we have watched them. The average of breeding water temperature was $21.5{\sim}24.5^{\circ}C$ (average $23.0{\pm}1.5^{\circ}C$). In yolk-sac larvae just after hatching, ossification was not observed at all, and when the average total length reached 2.66 mm, the premaxillary and maxillary forming the upper jaw, dentary forming the lower jaw, and parasphenoid forming the skull base were ossified. In addition, the preopercle and opercle forming the opercular region began to be ossified. The caudal skeleton supporting the caudal fin is built with the caudal complex consisting of the malleus and incus. Until the average total length reached 2.59 mm, ossification did not occur at all and the urostyle bent at 45-degree angle. As to the ossification of the pterygiophore, when the average total length was 6.12 mm, the first interhemal spine began to be ossified in articulation with two spines of the anal fin, and the synapse also began to be ossified in articulation with two spines of the dorsal fin. When the average total length was 21.9 mm, individuals with completed ossification of the interhemal spines and synaptic clefts began to appear.