• 한국패류학회지
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• 제21권1호
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• pp.1-11
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• 2005

Reproductive cycle, first sexual maturity, spawning amount related with the size and spawning interval in female Ruditapes philippinarum were investigated by histological observation and the analysis of morphometric data during artificial spawning induction. Ruditapes philippinarum is dioecious and oviparous. The reproductive cycle of this species can be subdivided into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (May to October), and spent/inactive stage (August to February). The spawning period was once a year between May and early October, and the main spawning occurred between July and August when seawater temperature was approximately $20^{\circ}C$. Percentages of first sexual maturity of female clam of 15.1-20.0 mm in shell length were 56.3%, and 100% for the clams > 25.1 mm. The mean number of the spawned eggs increased with the increase of size classes (shell length). In case of spawning induction by the same size class, the number of spawned eggs were gradually decreased with the increase of spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-17 days (average 16.5 days).

• 한국발생생물학회지:발생과생식
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• 제16권3호
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• pp.205-217
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• 2012

The ovarian cycle, the biological minimum size, and artificial spawning frequency by artificial spawning induction of the female hard clam, Meretrix petechialis, were investigated by histological observations and morphometric data. The ovarian cycle of this species can be classified into five successive stages: early active stage, late active stage, ripe stage, partially spawned stage, and spent/inactive stage. The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. The biological minimum size (shell length at 50% of first sexual maturity) in females were 40.39 mm in shell length (considered to be two years of age), and all clams over 50.1 mm in shell length sexually matured. In this study, the mean number of the spawned eggs by spawning induction increased with the increase of size (shell length) classes. In case of artificial spawning induction for the clams > 40.39 mm, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawning). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning of this species was estimated to be 15-18 days (approximately 17 days).

• 한국패류학회지
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• 제21권2호
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• pp.81-93
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• 2005

Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).

• Fisheries and Aquatic Sciences
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• 제4권4호
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• pp.208-218
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• 2001

We have investigated the gonad index (GI), gonadal development, reproductive cycle, first sexual maturity, sex ratio, the number of spawned eggs and spawning frequency of the Manila clam, Ruditapes philippinarum. Samples were collected from the intertidal zone of Komso Bay, Korea from January to December in 1999. Monthly changes in the gonad index (GI) and condition index showed a similar pattern in the reproductive cycle. The spawning period was once a year between early June and early October, there was a spawning peak between July and August when seawater temperature was over $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (June to October), and spent/inactive stage (August to March). Percentages of first sexual maturity of female and male clams of l5.1-20.0mm in shell length were $56.3\%$ and $60.0\%$, respectively, and $100\%$ for the clams >25. mm. The sex ratio of individuals >15.1 mm in shell length was about 1:1 $(\chi^2= 0.02,\;p>0.05)$. Number of the eggs released from each clam by the induction increased as the size of clam in terms of shell length increased. Mean number of the eggs from the second induction of the spawning was $75.35-84.30\%$ $(average\;79.81\%)$ of the number of the eggs released in the first spawning. Our data indicated that R. philippinarum in Komso Bay has one major spawning peak with over two minor spawning, and the interval of each spawning was estimated to be approximately 15-17 (average 16.5) days.

• 생태와환경
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• 제34권4호통권96호
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• pp.337-341
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• 2001

왜몰개, Aphyocypris chinensis의 산란에 미치는 수온의 영향을 알아보기 위하여, 19, 22, 25, $28{\circ}^C$ 수온에서 2개월 동안 사육을 하면서 산란횟수, 생산된 총 수정란 수, 산란간격 및 부화율 등을 조사하였다. $19{\circ}^C$와 $25{\circ}^C$사이에서는 수온이 증가하면 할수록 산란횟수, 생산된 총 수정란 수 및 수정란의 부화율이 증가하여 $25{\circ}^C$에 노출된 암컷과 수컷에서 가장 많은 산란횟수, 난 생산 및 부화성공률과 가장 짧은 산란간격을 나타냈다. 그러나 $28{\circ}^C$에서는 $25{\circ}^C$보다 수온이 증가했음에도 오히려 4개의 실험수온 중에서 가장 적은 산란횟수, 난 생산 및 부화율과 가장 긴 산란간격을 나타냈다.

• 한국패류학회지
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• 제19권2호
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• pp.153-153
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• 2003

2001년 1월부터 2001년 12월까지 전라북도 김제시 심포 앞바다에서 각장 18.6-52.7 mm 의 가무락조개 (Cyclina sinensis) 를 대상으로 자원증식 및 적정 관리를 위해 조직학적 방법에 의해 생식소발달단계에 따른 생식주기와 군성숙도를 조사하였고 인공산란 유도에 의해 산란량과 산란빈도를 조사하였다. 생식소 발달단계에 따른 생식주기를 조직학적으로 조사한 결과 가무락조개의 생식주기는 초기활성기 (2-4월), 후기활성기 (3-6월), 완숙기 (5-8월), 부분산란기 (7-9월), 퇴화 및 비활성기 (9-2월) 의 연속적인 5단계로 구분할 수 있었다. 7월부터 산란하기 시작하여 9월 중순까지 일어났고 산란성기는 7-8월이었다. 각장 25.1-30.0 mm인 암컷 개체들의 군성숙도는 64.3%이었고, 각장 40.1 mm이상인 개체들의 군성숙도는 100%이었다. 인공산란 유도에 의해 각 개체들로부터 방란된 난수는 개체들의 각장이 증가됨에 따라 증가되었다. 2차 산란유도에 의해 방란된 평균 난수는 1차 산란수의 평균 76.87%이었다. 가무락조개의 각 산란 간격은 대략 15-17일 (평균 16.5) 이었고, 한 산란기 중 2회 이상의 산란이 일어날 것으로 추정되었다.

• 한국발생생물학회지:발생과생식
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• 제1권2호
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• pp.173-180
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• 1997

This study has been conducted to investigate the molting behavior and the effects of rearing temperature and day length on molting in the behavior and the effects of rearing temperature and day length on molting in the giant freshwater prawn, Macrobrachium rosenbergii reared in the laboratory. The results obtained were summarized as follow: 1. After pre-spawning molting, the protopodites of 1st, 2nd, 3rd, and 4th except 5th pleopod bore new breeding setae which conserve eggs in the brooding chamber and the basis of 3rd, 4th, and 5th pereiopods bore new breeding dresses which transport the ovulated eggs into the brooding chamber. 2. Adult females reared in 27.5-$29.4^{\circ}C$ molted 10-12 times per year at interval of 27-35 days, of which four or six moltings were common molting for growth and another four or five moltings were pre-spawning molting for spwaning and brooding. In winter season, pre-spawning molting did not happen to most of adult females in spite of the same temperature. 3. Duration of intermolt cycle was 31-38 days and 26-30 days at 25.3- $26.5^{\circ}C$ and 28.7- $30.4^{\circ}C$ of rearing temperature, respectively.

• Ocean and Polar Research
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• 제39권2호
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• pp.73-84
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• 2017

The probability distribution of ichthyoplankton is important for enhancing the precision of sampling while reducing unnecessary surveys. To estimate the ichthyoplankton detection proportion (IDP) and its margin of error (ME), the monitoring information of the chub mackerel's (Scomber japonicus) ichthyoplankton presence-absence sampling data has been were collected over approximately 30 years (from 1982 to 2011) in the Korean coastal seas. Based on the computed spatial distributions of the mackerel's IDP and ME, the confidence interval (CI) range, defined as 2 ME, decreases from approximately 80% to 40% as the sample size n increases from 4 to 24 and the ME is approximately 40% in the typical (seasonal survey) case n = 4 per year. The IDP and ME off Jeju Island are relatively high at the 0.5-degree smoothing level. After increasing the spatial smoothing level to 1.0-degree, the ME decreased, and the spatial distribution pattern also changed due to the over-smoothing effects. In this study, the 0.5-degree smoothing is more suitable for the distribution pattern than the 1.0-degree smoothing level. The area of the high IDP and the low ME on the mackerel's ichthyoplankton was similar to the estimated spawning ground in the Korean peninsula. This information could contribute to enhancing for the spawning ecology surveys.

• 한국응용곤충학회지
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• 제58권3호
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• pp.219-224
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• 2019

Zophobas morio는 주로 애완동물의 먹이로 사용되고 있으며 대형어, 파충류, 양서류, 조류의 주식 및 간식으로 활용하기도 한다. Zophobas morio는 $27^{\circ}C$ 이상에서 사육하면 부화 후 80일째에 0.6 g 이상의 유충 무게를 얻었다. 보조사료를 선발하기 위해 콩가루, 어분, 보리, 메밀가루를 이용하였을 때 단백질 함량이 높은 콩가루와 어분에서 부화 후 80일째에 0.7 g이상의 유충무게를 확보하였다. Zophobas morio를 대량 사육하기 위해 성충의 산란율 증가와 균일한 유충을 확보하는 기술이 필요하다. 성충의 산란 격리틀을 이동시켜 줌으로써 유충 단계가 혼재되어 선발하는데, 노동력을 줄이며 높은 수확량과 균일한 유충을 확보하기 위해 5일, 10일, 15일 간격으로 성충을 산란틀로 옮겼을 때 5일 간격으로 성충을 옮기는 처리에서 총 부화유충수 7,256마리로 10일 5,439마리, 15일 2,060마리보다 더 많은 유충수를 확보할 수 있다. 따라서 Zophobas morio 성충을 5일 간격으로 산란틀을 옮기면서 산란을 9회 시키면 7,000마리 이상의 유충을 확보할 수 있으며 이때 한 마리당 무게는 0.68 g 확보가 가능하다.

• 한국수산과학회지
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• 제45권5호
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• pp.499-506
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• 2012

We estimated the population size and fishing mortality of Pacific cod Gadus macrocephalus during the spawning season in waters off Woipo, Geoje Island, Korea, using a mark-recapture method. We marked and released 51 cod>50 cm in total length; six were recaptured by local fishermen during the period from December 15 to 31, 2009. The estimated population size was ca. 180,000 and the fishing mortality of the exploitable cod was 26%. Although we could assume a closed population due to the short survey period, we evaluated the uncertainty in the estimates by applying bootstrap resampling because the sample size was small. The estimated 95% confidence interval was 94,000-568,000 for the population size and 8-49% for fishing mortality. Our study demonstrated that the application of mark-recapture methods and bootstrap resampling can be useful in stock assessment for fisheries management in Korea, but requires a larger sample size, spatially extensive coverage, and sophisticated mark-recapture models based on a refined sampling design for reliable stock assessment and biological reference points in sustainable cod management.