• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.308-316
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• 1987

The flying fish, Prognichthys agoo, is widely distributed in the coastal waters of south-eastern Korea. On July 14, 1986, mature adults of flying fish were captured from U-do, Cheju-do. The eggs were stripped and fertilized by the wet method on the ship. The mature eggs are demersal and adhesive with 30-40 filaments. The egg diameter varied from 1.42 to 1.58 mm. The water temperature throughout incubation ranged from 23.70 to $27.82^{\circ}C$, and salinity was maintained at $30.75-33.76\%_{\circ}$. The hatching took place in 174 hours after fertilization. The newly hatched larvae measured 4.75-5.25 mm in total length possessing yolk sac and about 45-46 myotomes. The larvae cultured for ten days after hatching reached 11.45-12.60 mm in total length and entered the juvenile period of life. Twenty days after hatching, the juveniles measured 20.01 mm in mean total length, and the scales were formed behind the pectoral fin.

• Journal of Aquaculture
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• v.14 no.1
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• pp.35-42
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• 2001

The larvae of the Korean bullhead, Pseudobagrus fulvidraco were satiated with the food uptake equivalent to 13% of its body weight and required 2.5, 11 and 15 hrs to digest 50, 90 and 100% of the consumed food. The juveniles were satiated with food equivalent to 0.65% of its body weight and required 9 and 19 hrs to digest 50 and 90% of the consumer. Apparently, daily food intake perceptibly decrease with the larvae grew to juvenile stage. Both larvae (8.3-14.0mm TL) and juvenile (41.1-65.7mm TL) tend to feed frequently than to get satiated once a day and appeared to be nocturnal feeders.

• The Korean Journal of Soil Zoology
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• v.8 no.1_2
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• pp.17-22
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• 2003

An endemic entomopathogenic nematode, Heterorhabditis megidis, was evaluated by its control efficacies against housefly, Musca domestica, and flower beetle, Gametis jucunda. In Petri-dish assay, the pathogenicity of H. megidis showed 456.4 infective juveniles/larva (IJs/larva) in median lethality (LC$_{50}$) against the second instar larvae of M. domestica and 238.9 IJs/larva against the second instar larvae of G. jucunda. This was contrasted with those of the other well-known entomopathogenic nematode, Steinernema carpocapsae, which showed 115.9 IJs/larva against M. domestica and 388.6 IJs/larva against G. jucunda. In field experiment, H. megidis were applied per square meter of pork farm with 1,000,000 IJs of H. megidis or apple orchard with 370,000 IJs, which were infested with M. domestica or G. jucunda, respectively. H. megidis showed 56.9% and 57.3% of control efficacies against M. domestica and G. jucunda, respectively. These results suggest a promising control technique in the field using H. megidis against M. domestica and G. jucunda.a.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.97-100
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• 2000

We report here an improved collecting method of the infective juveniles multiplied in the host insect with the entomopathogenic nematodes, Steinernema carpocapsae Weiser. The specific characteristics of this method involved the opening of the host insect hemocoel after the population of their infective juveniles reached at the maximum (6 days at 25$\^{C}$ after nematode treatment to nonimmunized host insects) to facilitate the escape of the multiplied nematodes. It also used 'Baermann funnel'method to select the infective juveniles effectively. This improved 'Baermann funnel'method was compared with a traditional collecting method, which was characterized with a combination of untreated host insects and 'White trap'collecting method, in both yield and pathogenicity of the collected infective juveniles to the fifth instar larvae of beet armyworm, Spodoptera exigua (H bner). More than 95% of the nematode populations collected by the two methods represented the morphological infective juveniles. To prove the nematodes to be infective juveniles functionally, pathogenicity and infective activity were compared in the nematodes collected by the two methods. They were not different in both pathogenicities and infective activities which were measured by the numbers of nematodes penetrated into the hemocoel of the insect hosts after exposure for the specific times to the same dote of infective juveniles. Significant difference between two collecting methods was found in the total yields of the infective juveniles per host insect About 50,000 infective juveniles per infected fifth instar larva of S. exigua after 6 day incubation at 25$\^{C}$ were collected only for 2 days by the improved 'Baermann funnel'method, while about 20,000 infective juveniles per host were collected for 10 days by the classical 'White trap'method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.2
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• pp.228-242
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• 2023

We examined the osteological development of the cranium, visceral skeleton, pectoral girdle, vertebral column, fins, and pterygiophore of small yellow croaker Larimichthys polyactis cultured at the Jeju Fisheries Research Institute. At 5.89 mm NL (notochord length), the larvae already had ossified frontal and basioccipital bones, parasphenoids, and vomer in the cranium. All elements of the visceral skeleton except the metapterygoid were ossified at 5.89 mm NL. Preorbital bone was ossified at 8.11 mm SL (standard length), and suborbital bones were ossified at 12.90 mm SL. In the vertebral column, ossification proceeded from the first to last centrum. The urostyle ossified at 7.41 mm SL. The caudal skeleton ossified at 6.78 mm NL, along with three hypural bones. In the pectoral girdle, the cleithrum, supracleithrum, postcleithrum, and post-temporal bones ossified at 5.89 mm NL. Caudal fin ossification began at 6.19 mm SL and was complete at 7.16 mm SL. Dorsal and anal fin ossification began at 7.16 mm SL and was complete at 8.62 mm and 8.11 mm SL, respectively. Anal and dorsal pterygiophore bone ossification was complete at 9.86 mm and 11.54 mm SL, respectively, and that of the supraneural bones was complete at 9.60 mm SL.

• Journal of Aquaculture
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• v.11 no.3
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• pp.303-310
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• 1998

The growth and survival rate of larvae and juveniles from female rockfish (Sebastes schlegeli) broodstock in vitellogenesis by injection of 3,5,3'-triiodo-L-thyronine $T_3$ with a dose of 20 mg/kg fish wt. were examined for 30 days and compared with sham-control fish injected dime-thyl sulfoxide and control fish. Larvae were fed with rotifers for first 5 days after parturition, rotifers and Artemia nauplii for next 10 days. And then, they were fed with Artemia nauplii and commercial diet. Growth of larvae and juveniles from maternal $T_3$injection was significantly faster than that of two controls, nevertheless, the condition factor was lower than that of controls. The whole body proximate analyses indicated that there were significant effects of $T_3$ injection on protein and lipid, but no significant on moisture and ash contents. Survival rate of the fish from maternal $T_3$injection was significantly higher than that of fish from the two controls. These results indicate that thyroid hormone supplements appear to confer a distinct advantage to larval and juvenile rockfish in early, fragile development stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.447-456
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• 1987

The osteological development of the larvae and juveniles of Prognichthys agoo was examined on the laboratory-roared materials of 5.06-20.01 mm in mean total length(MTL). Cranium, vertebrae, caudal skeleton, siloulder girdle bone, pelvic girdle bone, pterygiophore and jaw bones were descriued in detail to examine the sequences of ossification. Ossification of the cranium took place at ca. 5.06 mm of MTL in exoccipital, basioccipital, parasphenoid. Ossification of the visceral skeleton occurred in areas where active movements of bones were required, notably in the parts for feeding and respiration. Vertebrae began to develop from the anterior end and to ossify posteriorly. Neural and haemal spines of vertebrae ossified always prior to the corresponding centra. Urostyle bone developed as an elongated bone from the early larvae and ossified prior to the centra caudal part. In jaw bones, maxillary and a part of dentary appeared first at 5.06 mm of MTL and attained a fundamental structure at 9.30 mm of MTL. Ossification of all bones was nearly completed at ca. 20.01 mm of MTL.

• 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 Ichthyology
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• v.36 no.1
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• pp.1-9
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• 2024

This study investigated the early life history of the Boleophthalmus pectinirostris living in the southern coastal Yeoja-man and compared the results with the same Gobiidae fishes. The brood stork used in the study were captured with bare hands in the tidal flats of Beolgyo-eup, Jeollanam-do, in June 2015. The amount of spawning was 411~11,688, and the eggs were short oval and the size was 1.40×0.72 mm. The time of hatched took 91 hours and 35 minutes at a water temperature of 25~27℃. Newly hatching larvae, the yolk sac had a total length of 3.02~3.31 (average 3.17±0.08, n=30) mm and did not eat rotifer. 4 days after hatching, the total length was 3.31~3.52 (3.43±0.07, n=30) mm, and as the mouth and anus opened, the fish transitioned to the preflexion larvae and fed. 14 days after hatching, the total length was 5.06~5.25 (5.16±0.06, n=30) mm, and the distal end of the vertebra was completely bent at 45° and the transitioned to the postflexion larvae. 41 days after hatching, the total length was 14.3~16.8 (15.4±0.85 mm, n=30), and the number of fins reached an integer of 5 first dorsal fins, 26~27 second dorsal fins, 24~27 anal fins, and 6 ventral fins, and the transitioned to the juveniles. As a result of the study, star-shaped melanophore were deposited from the front of the pectoral fin to the base of the caudal fin, which distinguished them in form from other postflexion larvae of Gobiidae fishes.

• Journal of Aquaculture
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• v.5 no.1
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• pp.29-67
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• 1992

Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.