• 한국양식학회지
• /
• 제12권4호
• /
• pp.255-266
• /
• 1999

The early development, growth, and morphological changes of Tiger puffer Takifugu rubripes are described on the basis of a seres of a series of reared specimens. Detailed o수 the early developmental stages are illusrtated withe special reference to morphological transformation. Egg and sperm of puffer fish Takifugu rubripes were obtained from mature adults under natural conditions, ferilized artificially and incubated in the laboratory. The incubation period of fertilizd eggs was 160 to 180 hours at a temperature of $15.1~ 18.0^{\circ}C$. Larvae were fed successively with rotifer, Artemia nauplii and artificial food for 90 days. The mean total length of newly-hatched larvae was about 2.8mm. Mouth opening occurred on the 1- day yolk-sac larvae and initial feeding was observed on th 4-5 days after hatching . The morphological transitions from the larvae to juvenile and juvenile and juvenile to young stages occurred when fish reached about 10mm in total length(about 30 days after hatching) and about 32mm in total length(about 60days after hatching) , respectively. The coefficient of variation in total length distribution increased with growth. Following the appearance of its peak at the size of about 18mm in total length, the coefficient value declined. Many changes in proportion of the body parts to total length were observed at about 9~10mm and 30~33mm in total length, corresponding to the transformations from larvae to juvenile and from juvenile to young, respectively. Also one big morphological change was observed at about 18mm in total length that divide the juvenile stage into two sub-stages.

• 한국수산과학회지
• /
• 제51권3호
• /
• pp.332-337
• /
• 2018

The Pacific cod Gadus macrocepahlus, lays demersal eggs and the hatching larvae rise toward the surface layer of the ocean to feed. The change in the specific gravity of eggs and larvae was investigated to examine their vertical distribution and movement in the water column. The specific gravities of fertilized eggs and various size classes of larvae were measured using a density gradient apparatus. In total, the instantaneous specific gravity of 146 eggs and 225 larvae were measured. To prevent any disturbance in the gradient water column due to larval movement, 0.004% MS222 was used for anesthesia. Due to their high specific gravity, eggs spawned were deposited over the sea-bed of the spawning ground. The specific gravity of hatching larvae decreased abruptly. However, Pacific cod larvae still had a comparatively high specific gravity at hatching ($1.03655{\pm}0.00146g/cm3$, n=4, mean SL=3.62 mm) and their specific gravities tended to decrease as they grew. The specific gravity stabilized 6 days after hatching ($1.02590{\pm}0.00212g/cm3$, n=15, mean SL=4.67 mm) and the cod larvae were eventually able to float in the water column.

• 수산해양교육연구
• /
• 제28권1호
• /
• pp.180-185
• /
• 2016

두줄망둑 자치어기의 먹이생물을 조사하기 위하여 2012년 5월말부터 6월초 사이에 충남 서천군 서면 도둔리의 조간대에서 채집된 두줄망둑의 위내용물을 조사하였다. 섭식참여율은 낮 동안에 오전과 오후에 각각 한 차례씩 증가하는 경향을 보였다. 두줄망둑의 자치어의 주요 먹이생물은 copepods, amphipods, shrimp larvae, polychaete larvae 등이었으며, 이들이 건중량의 2% 이상을 차지하였다. 그중에서 copepods가 평균 65.5%로 가장 많은 양을 차지하였고, polychaete larvae, shrimp larvae 등의 순으로 많이 출현하였다. 먹이생물의 개체수 조성비를 보면, copepods가 65.4%를 차지하여 가장 높았고, polychaete larvae는 22.6%, shrimp larvae는 14.5%를 차지하였다. 먹이생물 중 copepods는 개체수 조성비가 높고 출현율도 높아서, IRI가 5,369.3으로 가장 높은 수치를 나타내었고, polychaete larvae는 653.1, shrimp larvae는 287.1의 수치를 나타내었다. 따라서 두줄망둑의 자치어기의 가장 중요한 먹이생물은 copepods, polychaete larvae, shrimp larvae 등이었다.

• 한국발생생물학회지:발생과생식
• /
• 제24권1호
• /
• pp.63-70
• /
• 2020

This study aimed to investigate early life of Coreoperca herzi living in Han River and compare morphological differences between different groups during the development in order to provide basic data for relevant taxonomic research. On average, one female individual spawned 541 to 861 eggs (average 701) at once. After 259 hours, the tail broke out of the egg membrane and hatching began. Immediately after hatching, the larvae were average 7.81±0.10 mm (n=5) in total length. 60 days the juvenile was average 35.9±1.30 mm (n=5) in total length. The white spots spread to the rest of the body, rending the same pattern as that on the body of their broodstock fish.

• 한국패류학회지
• /
• 제1권1호
• /
• pp.5-12
• /
• 1985

The maturity of gonads, early development of the fertilized egg, spawning period, and morphogenesis of larvae in Limnoperua fortunei were studied from October, 1981 to November, 1982 as on attempt to identify its life cycle. 1) Active motility of its sperm was observed at late May, and matured egg could be found at late June. 2) It was estimated that the spawning was occured from late August. This species was belong to the short-term breeder because it finished its spawning within 20 days. 3) It has free-living trochophore and D-shaped larva stage. The shell lengths of early, middle, and D-larval stage were $140.0{\mu}m$, $167.6{\mu}m$ and $210.0{\mu}m$, respectively. The shell heigths of each stage were $97.3{\mu}m$, $137.6{\mu}m$ and $178.2{\mu}m$, respectively.

• 한국어류학회지
• /
• 제26권1호
• /
• pp.17-24
• /
• 2014

한국 고유종인 큰줄납자루 Acheilognathus majusculus의 종 보존을 위한 기초 자료를 확보하기 위해 난 발생과 자어의 성장을 관찰하고 초기생활사 특성을 논의하였다. 수정란은 둥근 타원형으로 평균 장경이 2.12mm(2.08~2.18 mm), 단경이 1.86mm(1.80~1.98 mm)이며 담황색 난황을 가진 분리침성란이다. 개체 당 산란 수는 40~112개(평균 72개)였고 수정란은 수온 $18.0{\pm}1.0^{\circ}C$에서 수정 후 43시간 만에 부화하였다. 부화 직후 자어의 크기는 4.23mm이고 형태적으로 납자루속의 자어 특성을 공유하고 있으며 자어 시기의 S자 운동은 없었다. 부화 후 25일 경에 소화기관이 완성되고 외부 먹이를 먹을 수 있어 자연에서 조개로부터 부출하는 시기로 추정된다. 만 1년 후에는 재생산이 가능한 크기로 성장한다.

• 한국수산과학회지
• /
• 제41권6호
• /
• pp.478-484
• /
• 2008

To elucidate the spawning behavior and early life history of Liobagrus mediadiposalis, mature male and female fish were collected from a branch of the Seomjin River. Spawning was induced by injecting hormones, and then the spawning process and development of fertilized eggs, larvae, and juveniles were observed. Observations of spawning behavior showed that the female established a territory and built a spawning nest, and frequently pressed on the upper ventral part of the male to release her eggs. When spawning was finished, the fish supplied fresh water to the egg mass using their pectoral and caudal fins. Hatching began 189 h 20 min after fertilization at $21.5-23.5^{\circ}C$ (mean $22.7^{\circ}C$). The mean total length (TL) of newly hatched larvae was 7.18-7.39 mm (mean 7.31 mm). Their mouth and anus were already open and they had 14+24=38 myotomes. Eighteen days after hatching, the larvae were 12.71-13.79 mm (mean 13.27 mm) in TL and the yolk sac was absorbed completely. At 35 days after hatching, when all the fin-rays had formed, the juveniles were 15.84-17.92 mm (mean 16.33 mm) in TL.

• 한국응용곤충학회지
• /
• 제23권2호
• /
• pp.132-136
• /
• 1984

전남지방의 밤 집단재배단지에서 피해가 확대되고 있는 밤바구미의 피해율, 발생시기, 토중의 월동부위, 월동후의 사충율의 변이에 대한 시험을 계획한 바 다음과 같은 결과를 얻었다. 1. 전남지방 밤 단지의 밤바구미 피해율은 담장 $26.4\%$, 광양 $21.1\%$, 승주 $12.9\%$였으며 이 지역은 참나무류가 많이 혼재되어 있었다. 2. 월동유충의 약 $3.33\%$가 1년차에 우화되었고, $22.78\%$가 2년차에, 그리고 $1.67\%$가 3년차로 계속 월동중이었다. 3. 밤바구미의 우화시기는 7월 중순부터 9월 중순까지였고 그 최성기는 8월 중순에서 9월 상순이었다. 4. 밤바구미 피해종실로부터의 유충 탈출시기는 10월 상순부터 11월 상순이었다. 5. 밤바구미의 난기는 5.95일, 용기는 17.17일, 성충의 수명은 암컷 9.10일, 숫컷 7.03일 이었으며 유충기간은 매우 다양하여 측정하기 어려웠다. 6. 밤바구미는 월동유충은 상중 $16\~26cm$에 많이 분포하였다. 7. 월동후 일수경과에 따른 사충율과는 고도의 유의상관관계$(r=0.970^{**})$가 인정되었다.

• 한국해양학회지
• /
• 제11권1호
• /
• pp.1-8
• /
• 1976

피조개, Anadara broughtonii(SCHRENCK)는 근년에 와서 산업적 가치가 높아짐에 따라 중요 양식대상종으로 많은 연구의 대상이 되고 있다. 인공 및 천연채묘에 관해서는 관야91963), 이등 외(1967), 금정 외(1969), 전중(1971)등의 연구와 중간양성에 관해서는 관야 외91966)의 연구가 보고되고 있으며 유91969, 1970)는 먹이 및 성장에 관해서 보고한 바 있다. 본고에서는 피조개의 산란 및 유생의 출현상황과 분표에 영향을 미칠것으로 추측되는 몇가지 환경요인을 관찰하여 검토한 결과를 보고한다.

• Ocean Science Journal
• /
• 제40권1호
• /
• pp.11-16
• /
• 2005

Correction factors based on the catch ratios of egg and larval densities in the southern waters of Korea were estimated for anchovy Engraulis japonica. This was undertaken in order to adjust ichthyoplankton data from different sampling methods, gear types and time. Samples were collected during ichthyop1ankton surveys in Korean waters from 1983 to 1994. The ratios for egg densities obtained in vertical tows with a NORPAC net (ring $\Phi$, 45 cm) compared to those obtained in oblique tows with a KOB net (ring $\Phi$, 80 cm) were 0.86 (CV = 0.65), 1.22 (CV = 0.36), and 0.93 (CV = 0.42) for early, middle, and later developmental stages, respectively. The ratios for larval densities for vertical and oblique tows varied depending on size. For yolk-sac and small larvae (< 4 mm), the ratios were 3.08 (CV = 0.45) and 1.98 (CV = 1.34), while those of 4-6 mm, 6-8 mm, and 8-10 mm larvae were 0.44 (CV = 1.31), 0.45 (CV = 1.70), and 0.56 (CV = 2.50), respectively. Ratios of day/night densities for larvae of 4-10 mm lengths were lower (0.01-0.06) in offshore catches than values obtained in coastal areas (0.440.46) and similar values (0.16-0.04) for vertical and oblique tows. Our results indicated that vertical towing is more efficient for sampling early life stages (from eggs to larvae less than 4 mm long), while oblique towing is more efficient for larvae longer than 4 mm due to depth preferences for each developmental stage (e.g., changes in egg buoyancy and vertical migration oflarvae).