• 수산해양기술연구
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• 제54권2호
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• pp.188-192
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• 2018

The reproduction characteristics of hagfish Eptatretus burgeri were examined using individuals caught in the South Sea of Korea. The spawning season and size at minimum sexual maturity of this species were characterized based on a gonad-somatic index (GSI) and monthly variation egg size (long axis). From monthly variation of GSI, the spawning season was estimated to be from August to September. Developing eggs larger than 10 mm were found in March, and the largest egg size was found in July. The first spawning length was 34.2 cm TL. Batch fecundity ranged from 13 to 117 eggs for hagfish sized from 34.2 cm TL to 77.0 cm TL, respectively, and increased linearly with total length.

• 수산해양기술연구
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• 제47권3호
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• pp.194-202
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• 2011

Maturation and spawning of the Shotted halibut, Eopsetta grigorjewi was investigated based on the samples captured in South Korean waters from January 2008 to December 2009. Gonadosomatic index began to increase in December, and reached maximum between January to March. After spawning it began to decrease from May. Reproductive season was estimated to January-April, with peak in February. Fecundity was proportional to the size of the female, with the clutch size varying from 170,000 eggs in the smallest female (total length, 28.9cm) to 1,300,000 eggs in the largest (total length, 41.5cm). Size at 50% sexual maturity (TL50), determined from mature females, was 28.8cm. Annual reproductive cycles of this species could be divided into six successive stages; immature stage (May-October), nucleolus stage (November-January), yolk vesicle stage (January-February), vitellogenic and ripe stage (January-April) and spent stage (April-May).

• 한국패류학회지
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• 제17권1호
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• pp.45-55
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• 2001

일본재첩의 자원관리를 위한 기초조사로 배우자 형성과정 및 생식주기, 군성숙도, 발생과정 등을 조사한 결과, 자웅이체 난생 종으로 암컷의 생식소는 회흑색, 수컷의 생식소는 유백색을 띄어 육안적으로 뚜렷히 구별되었다. 배우자의 형성과 성장은 수온에 지배되는 것으로 나타났으며, 성숙한 난모세포는 원형으로 그 크기는 약 80$\mu\textrm{m}$ 전후였다. 생식주기는 초기활성기 (2-4월), 후기활성기 (5-7월), 완숙기 (6-9월), 부분산란기 (7-9월), 퇴화 (9-10월) 및 비활성기 (10-익년 5월)의 연속적인 5 단계로 구분할 수 있었으며, 방란.방정후 생식소 자체가 완전히 퇴화되지 않고 새로운 조직에서 신생되면서 비활성기를 지나 이듬해 봄에 다시 분화가 활발히 개시되었다 따라서 일본재첩의 번식생태는 긴 생식소의 발달기간에 비해 짧은 방란.방정기를 가지는 종으로 특징 지워진다. 자원의 증식과 관리를 위한 자료로 매우 중요한 군성숙도를 조사한 결과 암컷과 수컷의 50% 개체가 각각 생식에 참가하는 각장은 약 10-12 mm로 추정되었고, 각장 16 mm 이상이면 전 개체가 생식에 참가하는 것으로 나타났으며, 생식에 참가하는 최소각장에 있어 암.수 개체간 차이는 볼 수 없었다. 방출된 알은 분리침성란으로 수정란의 난경은 약 80-90 $\mu\textrm{m}$ 범위에 있었으며, 수온 26.5-28.$0^{\circ}C$에서 수정 후 약40분이 지나면서 극체 (polar body) 가 방출되었다. 수정 14시간 후에는 낭배기, 27시간 후에는 담륜자기로 발생하였다. 이어 수정후 4일경부터 유각이 형성되고 폐각근, 장관, 면반 등이 분화된 D형 자패가 출현하였다. 개체간 성장 차이는 있었지만 57일간의 사육일수에 대한 각장과 각고의 상대성장식을 구한 결과, 사육일수 (X) 에 대하여 각장 (Y) 의 성장은 Y = 14.4X + 209.58 ($r^2$= 0.9078), 각고 (Y) 는 Y = 11.5l7X + 167.48 ($r^2$= 0.8744)로 나타났다.

• 한국어류학회지
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• 제7권2호
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• pp.150-159
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• 1995

1992년 5월부터 1993년 8월까지 부산 수영만 인근해역에서 채집된 망상어, Ditrema temmincki를 대상으로 조직학적 방법에 의해 생식주기와 군성숙도를 조사하였다. 조사된 결과는 다음과 같다. 본종의 군성숙도는 수컷은 체장 13.5cm, 암컷은 체장 12.5cm로 조사되었다. 생식소중량지수는 수컷은 10월, 암컷은 6월에 연중 가장 높은 값을 나타냈다. 정소의 내부조직상은 곡정세관형이며, 난소는 5∼6장의 난소습곡으로 이루어져 있는데, 곡정세관상피와 난소습곡상피에서 각각 정원세포와 난원세포가 유래한다. 생식주기는 수컷은 성장기(5∼8월), 성숙기(9∼10월), 교미기 (11∼12월), 퇴화 및 휴지기 (1∼4월)로 나눌 수 있으며, 암컷은 성장기 (9∼10월), 교미 및 성숙기 (11∼12월), 임신기 (1∼6월), 휴지기 (7∼8월)로 나눌 수 있다. 간중량지수는 암수 모두 4월에 최고치를 보여, 수컷에서는 생식소중량지수의 월변화와 역상관 관계를 보이고, 암컷에서는 정상관 관계를 보였다.

• 한국패류학회지
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• 제20권1호
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• pp.75-84
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• 2004

Reproductive cycle, the condition index, sex ratio of the Pacific oysters, Crassostrea gigas were investigated by histological and morphometric data. The specimens were collected in the two oyster farms of Geoje and Namhae, Gyeongsangnam-do, Korea, from November 1995 to October 1996. Growth of shell length in two regions was similar, but growth of total weight of the oyster in Namhae was faster than that in Geoje oyster farm. The spawning periods in female and male clams were from July to October in Geoje and from June to October in Namhae oyster farm. Ripe oocytes were approximately 50 m in diameter. The reproductive cycle of in females and males in Geoje and Namhae oyster farms can be divided into five successive stages: early developing, late developing, ripe, partially spawned and spent/inactive. Monthly changes in gonad developmental phases showed somewhat different patterns between female and male clams except for the spawning period. On the whole, however, monthly changes in the gonad developmental phases showed a similar pattern in the same sex. The sex ratios of females to males in Geoje and Namhae oyster farms were not significantly different from a 1:1 sex ratio ($x^2$ = 0.55 (p > 0.05) in Geoje and $x^2$ = 0.27 ( p > 0.05) in Namhae). Artificial induction of maturation by heating of adult oysters (two-year-old) was investigated from 17 January to 18 March in 1996. Maturity at the fixed water temperature group of $20^{\circ}C$ was 80%, it showed the highest maturity of experimental groups cultured for five weeks. The survival (%) of Crassostrea gigas in the raised water temperature experimental groups (15, 20, $25^{\circ}C$) were over 98.5%, as similar to the control group (100%). But, the survival of C. gigas in the fixed water temperature experimental groups (15, 20, 25, $30^{\circ}C$) were decreased with the increase of the water temperatures. In the fixed water temperature experimental group of $30^{\circ}C$, the survival was 51.1%. Base on these results, the fixed water temperature of $20^{\circ}C$ was the best condition for artificial induction of sexual maturation.

• 한국수산과학회지
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• 제39권4호
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• pp.349-356
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• 2006

Gonad development in the sandfish Arctoscopus japonicus was investigated using a histological method. Specimens were collected monthly from April 2003 to March 2004, in the East Sea of Korea. The gonadosomatic index (GSI) of females began to increase in August, reached a maximum in November, and declined sharply in December. By contrast, in males, the GSI began to increase in June and reached a maximum in August. The annual reproductive cycle of A. japonicus can be divided into four successive stages in females: the early growing (January-March), late growing (April-August), ripe and spent (September-November), and recovery (December) stages. Males passed through early growing (January-April), late growing (May-July), ripe and spent (August-November), and recovery (November-December) stages. These results indicate that the spawning season was from October to December. The egg diameter of mature oocytes was 3.12$\pm$0.02 mm. The relationship between fecundity (F$_e$) and body length (BL) was F$_e$=0.4693BL$^{2.6825}$. Fecundity ranged from 483-2,254 eggs in a body length of 14.3-22.9 cm and increased with body length. The body length at 50% maturity was 14.80 cm, which corresponded to an age of 2.40 years.

• 한국수산과학회지
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• 제38권2호
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• pp.112-117
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• 2005

Sargassum fulvellum (Turner) C. Agardh, an edible brown alga is farmed commercially by sexual reproduction and vegetative regeneration. Investigations were made on the phenology, abundance and maturity of reproductive structures in mature fronds, egg release and young germling development under different light conditions (20, 50, 80 and $100{\mu}mol/m^2/s$) and temperatures (5, 10, 15, 20 and $25^{\circ}C$). Monthly sampling was carried out by SCUBA diving at Chungsando on the southwestern coast of Korea from September 2002 to August 2003. The Maximum length of thalli was $104.6{\pm}20.7{\cal}cm$ in March 2003 when the water temperature was $9.0^{\circ}C$ and minimum was $0.8{\pm}0.5{\cal}cm$ in June when the water temperature was $19.5^{\circ}C$. Receptacle formation was observed from February to April. The peak period of egg release for this alga was in April when the water temperature was about $10^{\circ}C$ in nature. In the culture regimes of temperature and irradiance, the egg release of the excised female receptacle was highly affected by temperature. The maximum rate of egg release was $96.7{\pm}5.8{\%}$ under $20^{\circ}C$ and $80{\mu}mol/m^2/s$. The maximum length of young germlings was $3.9{\pm}0.2{\cal}mm$ after 35 days culture under $15^{\circ}C$ and $80{\mu}mol/m^2/s$.

• 수산해양기술연구
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• 제48권3호
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• pp.217-226
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• 2012

Reproductive ecology of the sharp toothed eel, Muraenesox cinereus was investigated based on the samples captured in southern Korean waters from January 2010 to December 2011. Gonadosomatic index began to increase in April, and reached maximum between July to August. After spawning it began to decrease from October. Reproductive season was estimated to April-September, with peak in July. Fecundity was proportional to the size of the female, with the clutch size varying from 56,000 eggs in the smallest female (anal length, 27.0cm) to 1,400,000 eggs in the largest (anal length, 49.5cm). Size at 50% sexual maturity ($AL_{50}$), determined from mature females, were 21.9cm. Annual reproductive cycles of this species could be divided into four successive stages; immature stage (October-February), maturing stage (March-May), mature stage (June-August) and spent stage (August-October).

• 한국발생생물학회지:발생과생식
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• 제12권2호
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• pp.169-181
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• 2008

2006년 1월부터 12월까지 한국 서해안 무안군 자운도 주변해역에서 안강망으로 채집한 병어, Pampus argenteus를 대상으로 조직학적 조사 및 형태 측정에 의해 번식 생태를 조사하였다. 병어는 자웅이체이며, 난소는 한 쌍의 낭상구조를 하고 있으며, 수많은 난소소엽으로 구성되어 있다. 정소는 엽상구조를 하고 있으며, 수많은 정소소엽으로 구성되어 있다. 암 수 개체들의 생식소중량지수(GSI), 간중량지수(HSI), 비만도지수(CF) 값들의 월별 변화는 2월(초기 성장기)부터 8월 (회복기 시작)까지는 생식소 발달단계와 아주 유사한 경향을 보이며 변하였다. 이들 지수값의 변화로부터 암컷과 수컷 개체들의 방란, 방정은 5월부터 7월까지 일어나는 것으로 추정되었다. 병어의 생식주기는 암컷의 경우, 초기성장기(2$\sim$3월), 후기성장기(3$\sim$4월), 성숙기(3$\sim$7월), 완숙 및 산란기(5$\sim$7월), 회복 및 휴지기(7$\sim$2월)로 구분되었다. 수컷의 경우는 성장기(2$\sim$4월), 성숙기(3$\sim$6월), 완숙 및 방정기(5$\sim$7월), 회복 및 휴지기 (7$\sim$2월)로 구분되었다. 월별 난경 조성 빈도 분포 변화로 보아 병어의 산란빈도수는 한 산란기 중 한 개체가 적어도 2회 또는 그 이상 산란하는 다회 산란종으로 추정되는 춘하계 산란종이다. 체장당 절대포란수의 총 난수는 체장이 커짐에 따라 절대포란수의 총 난수는 증가되는 경향을 보였으며, 상대포란수(cm 당)의 총 난수도 체장이 커짐에 따라 상대포란수(cm 당)의 총 난수가 증가되는 경향을 보였다. 체중당 절대포란수의 총 난수는 체중이 증가됨에 따라 절대포란수의 총 난수는 증가되는 경향을 보였다. 그러나 체중당 상대포란수(g 당)의 총 난수는 체중이 증가됨에 따라 증가되나, 일정 체중 이상으로 커지면, 오히려 체중 증가에 따라 상대포란수의 총 난수가 감소하는 경향을 보였다. 군성숙도 50%에 해당하는 체장은 12.1$\sim$15.0 cm(만 1세 이상에 해당)이었고, 군성숙도 100%에 해당되는 체장은 18.1$\sim$21.0 cm(만 3세에 해당)이었다. 따라서 병어는 만 1세 이상이 되면 전체 개체의 50%가 성숙에 도달하여 재생산(산란)에 가담할 수 있는 것으로 추정되었다.

• Animal Bioscience
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• 제34권4호
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• pp.471-481
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• 2021

Objective: A comprehensive study was conducted to study the effects of partition of variance on accuracy of genetic parameters and genetic trends of economic traits in Vanaraja male line/project directorate-1 (PD-1) chicken. Methods: Variance component analysis utilizing restricted maximum likelihood animal model was carried out with five generations data to delineate the population status, direct additive, maternal genetic, permanent environmental effects, besides genetic trends and performance of economic traits in PD-1 chickens. Genetic trend was estimated by regression of the estimated average breeding values (BV) on generations. Results: The body weight (BW) and shank length (SL) varied significantly (p≤0.01) among the generations, hatches and sexes. The least squares mean of SL at six weeks, the primary trait was 77.44±0.05 mm. All the production traits, viz., BWs, age at sexual maturity, egg production (EP) and egg weight were significantly influenced by generation. Model four with additive, maternal permanent environmental and residual effects was the best model for juvenile growth traits, except for zero-day BW. The heritability estimates for BW and SL at six weeks (SL6) were 0.20±0.03 and 0.17±0.03, respectively. The BV of SL6 in the population increased linearly from 0.03 to 3.62 mm due to selection. Genetic trend was significant (p≤0.05) for SL6, BW6, and production traits. The average genetic gain of EP40 for each generation was significant (p≤0.05) with an average increase of 0.38 eggs per generation. The average inbreeding coefficient was 0.02 in PD-1 line. Conclusion: The population was in ideal condition with negligible inbreeding and the selection was quite effective with significant genetic gains in each generation for primary trait of selection. The animal model minimized the over-estimation of genetic parameters and improved the accuracy of the BV, thus enabling the breeder to select the suitable breeding strategy for genetic improvement.