• 한국해양생명과학회지
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• 제7권1호
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• pp.37-44
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• 2022

연구는 기름가자미의 성비, 군성숙도 및 주 산란기에 관한 정보를 얻기 위해 수행하였다. 성비(암:수)는 1:0.54 (n=189:103, 암컷 64.7%)였으며, 전장이 증가함에 따라 암컷의 비율이 높아지는 경향을 보였다. 난모세포 발달패턴은 동일 난소 내에서 여러 단계의 난모세포군이 확인되는 난군동기발달형이었다. 로지스틱 회귀모델에 의해 분석된 50% 성숙 전장은 암, 수 각각 28.51 cm과 30.49 cm였다. GSI는 암, 수 각각 4월과 3월에 가장 높았으며, 주 산란기는 4-5월로 분석되었다.

• 한국패류학회지
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• 제28권4호
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• pp.363-375
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• 2012

The gametogenic cycle, the number of spawning seasons per year and first sexual maturiity of the pen shell, Atrina (Servatrina) pectinata, were investigated by quantitative statistical analysis using an Image Analyzer System. Compared two previous results (the spawning periods in the reproductive cycles in 1998 and 2006) by qualitative histological analysis with the present results by quantitative statistical analysis, there are some differences in the spawning periods: the spawning period (June to September) by quantitative statistical analysis was one month longer than those of two previous reports (June to July or June to August) by qualitative histological analysis. However, the number of spawning seasons studied by the qualitative and quatitative analyses occurred once per year. In quantitative statistical analysis using an image analyzer system, the patterns of monthly changes in the percent (%) of the areas occupied by follicles to the ovary area in females (or that of the areas occupied by spermatogenic stages to the testis area in males) showed a maximum in May, and then sharply droped from June to September, 2006. From these data, it is apparent that the spawning season of A. (S.) pectinata occurred once a year from June to September, indicating a unimodal gametogenic cycle during the year. Shell heights of sexually mature pen shells (size at 50% of group sexual maturity, $GM_{50}$) that were fitted to an exponential equation were 15.81 cm in females and 15.72 cm in males (considered to be one year old).

• 한국작물학회지
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• 제33권1호
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• pp.70-73
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• 1988

풋찰옥수수의 수확적기를 구명하기 위하여 1984년 수원과 청주에서 홍천재래을 공시하여 출사(수원에서는 수분)후 15일부터 40일까지 5일 간격으로 6회에 걸쳐 수확하여 종실의 발육, 수분 및 전당함량, 삶은 옥수수의 맛, 찰기, 경도 등을 조사한 결과를 요약하면 다음과 같다. 1. 입장과 입폭은 출사후 15일부터 30일까지 크게 증가하였고 그 후 다소의 증가에 그쳤으며 입후는 출사 20일 이후 거의 증가되지 않았다. 2. 생체 100립중은 출사후 30일까지 크게 증가된 반면 그 후에는 다소의 증가에 그치였고 건물 100립중은 출사후 15일부터 40일까지 거의 직선적인 증가를 보였다. 3. 종실의 수분함량은 성숙정도가 진전됨에 따라 직선적인 감소를 보였다. 전당함량은 출사후 20일에 가장 않았고 그 후 감소되었다. 4. 맛과 찰기는 출사후 15일부터 30일까지 크게 증가되었고 맛은 그 후 감소되었으나 찰기는 출사후 35일까지 같은 수준을 유지하였다가 그 후 다소 감소되었다. 식용에 알맞는 경도는 출사후 30∼35일 이었다.

• 한국어류학회지
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• 제19권2호
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• pp.101-106
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• 2007

본 연구는 2003년 3월부터 2004년 4월까지 강원도 연안에서 유자망어업에서 어획된 대구횟대를 매월 채집하여 성숙과 산란에 관하여 조사한 것이다. 대구횟대의 산란기는 생식소성숙도지수, 난경 등의 월별 변화에 의한 결과 12월에서 이듬해 2월로 추정되어졌다. 체장과 포란수와의 관계는 $F=285.11TL^{1.4092}$ ($R^2$=0.571)이었으며 체중과 포란수와의 관계는 $F=1.449.8BW^{0.5514}$ ($R^2$=0.577)이었으며, 포란수는 어체가 커질수록 증가하였다. 최소포란수로 8.814립 (TL: 14.7 cm), 최대포란수는 28,560립 (TL: 24.4 cm)이었다. 최소성숙체장은 15 cm였으며, 이때의 나이는 약 2세였다. 체장계급별 성비는 소형어에서는 수컷이 약간 우세하였으나 24 cm 이상에서는 암컷이 90%로 높게 나타났다.

• 한국패류학회지
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• 제27권1호
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• pp.43-53
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• 2011

The gametogenic cycle and the spawning season in female and male Cyclina sinensis were investigated by quantitative statistical analysis using an image analyzer system, and the biological minimum size (the size at 50% of sexual maturity) was calculated by combination of quantitative data by size and von Bertalanffy's equation. Compared the gametogenic cycle by quantitative statistical analysis with the previous qualitative results in female and male C. sinensis, monthly changes in female and male gametogenic cycles calculated by quantitative statistical analysis showed similar patterns to the gonadal stages in female and male reproductive cycles by qualitative histological analysis. Comparisons of monthly changes in the portions (%) of each area to eight kinds of areas by quantitative statistical analysis in the gonads in female and male C. sinensis are as follows. Monthly changes in the portions (%) of the ovary areas to total tissue areas in females and also monthly changes in the portions of the testis areas to total tissue areas in males increased in March and reached the maximum in May, and then showed a rapid decrease from June to October. Monthly changes in the portions (%) of oocyte areas to ovarian tissue areas in females and also monthly changes in the portions of the areas of the spermatogenic stages to testis areas in males began to increase in March and reached the maximum in June in females and males, and then rapidly dropped from July to October in females and males when spawnig occurred. From these data, it is apparent that the number of spawning seasons in female and male C. sinensis occurred once per year, from July to October. Monthly changes in the number of the oocytes per mm2 and in the mean diameter of the oocyte in captured image which were calculated for each female slide showed a maximum in May and reached the minimum from December to February. Therefore, C. sinensis in both sexes showed a unimodal gametogenic cycle during the year. The percentage of sexual maturity of female and male clams ranging from 25.1 to 30.0 mm in length was over 50% and 100% for clams over 40.1 mm length. In this study, the biological minimum size (sexually mature shell lengths at 50% of sexual maturity) in females and males were 26.85 and 26.28 mm, respectively.

• Fisheries and Aquatic Sciences
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• 제26권6호
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• pp.380-392
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• 2023

Groupers (Family Epinephelidae) are commonly caught in data-poor small-scale multi-species fisheries for sale on both export and domestic markets. This study presents data on the species composition and size/life-stage structure of Epinephelus spp. groupers caught by small-scale fishers and sold locally in the Indonesian province of South Sulawesi. Data were collected from fishing ports and local markets at 12 sites representing the three seaways around South Sulawesi (Makassar Strait, Flores Sea, Gulf of Bone). Each specimen (n = 3,398) was photographed alongside an object of known length, and total length (TL) was obtained using the Rapid Scaling on Object (RASIO). Of the 23 species identified, four (Epinephelus areolatus, Epinephelus ongus, Epinephelus quoyanus, and Epinephelus fasciatus) collectively comprised 69% of the catch, while the 13 least abundant species contributed less than 5%. The catch was dominated (67%) by the subadult life-stage, with just under 20% in the adult class. Juveniles dominated the catch of Epinephelus fuscoguttatus, a valuable export commodity. Observations of early maturity as well as the sizeable gap between length at first capture (Lc) and length at first maturity (Lm) indicate recruitment overfishing of most species, with the notable exception of Epinephelus rivulatus. The proportion of adult fish was low (≈5%-30%) for the twelve most abundant species (E. areolatus, E. ongus, Epinephelus quoyanus, E. fasciatus, Epinephelus coioides, Epinephelus faveatus, Epinephelus sexfasciatus, Epinephelus maculatus, Epinephelus bleekeri, Epinephelus corallicola, E. fuscoguttatus, Epinephelus polyphekadion). For two moderately abundant species (E. faveatus and E. malabaricus), TL < Lm for all specimens. The limited data available indicate spawning ratio is lower than reported from deep-water fisheries of E. areolatus and E. coioides. The results call for targeted research to fill knowledge gaps regarding the biology and ecology of groupers exploited mainly for domestic markets; highlight the need for species-level data to inform management policies such as minimum legal size regulations; and can contribute towards species-level status assessments.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.403-410
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• 2011

Scartelaos gigas is an amphibious mudskipper species that inhabits mud flats in Korea, China, and Taiwan. This fish is at risk of extinction because of its very restricted habitat and overexploitation. Information about this fish's reproductive characteristics is needed for species conservation. The sexual maturity and early life history of S. gigas were investigated through histological methods and direct observation of eggs in the wild, respectively. In total, 560 individuals of S. gigas were collected with the aid of fishermen from March 2003 to October 2003 at Jung-do Island, southwest Korea. Through microscopic observations of gonadal development, it was determined that S. gigas of both sexes were immature in April, but began to reach maturity in May, and were then fully mature by June, which was maintained until July. In August, some female fish developed early oocytes, but by September oocytes were observed to have degenerated and had been absorbed. Spawned eggs were elliptical and had an average size of 1.37 mm (long axis) by 0.69 mm (short axis). The newly hatched larvae (3.03 mm total length, TL) had an open mouth and anus, two melanophores near the anus, and one large melanophore between the 18th and 19th myomeres. The larvae (3.18 mm TL) showed absorption of the yolk and oil globule within 5 days after hatching and became prelarvae. This species should be considered vulnerable or conservation-dependent, and thus parental fish need to be protected from fishermen during the main spawning season (June).

• 한국수산과학회지
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• 제38권4호
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• pp.245-250
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• 2005

The maturity and spawning of Pacific cod, Gadus macrocephalus, was studied using samples caught by gillnets in the East Sea from January to December 2003. Monthly changes of maturity observed with the naked eyes for females showed that maturing Pacific cod appeared from August, and their numbers increased to $83\%\;and\;100\%$ in November and December, respectively. In January, mature and spawning Pacific cod were observed for the first time and composed over $40\%$ of the population. In February, the proportion of spawning individuals increased to over $50\%$, however, the mature individuals decreased to less than $10\%$. In March, mature fish were not found, and all were in an immature (spent) or spawning state. From April to July all fish remained in immature condition. The males maintained this trend with the females, whereas, mature males appeared from November to March. Monthly changes in the gonadosomatic index (GSI) of females and males showed higher values both in January and February and declined sharply in March. The lower value remained until October and then began to increase from November for the female population. For the males, however, this value remained lower until August, and then began to increase from September, and showed higher values in October through December than in January and February. These results indicated that the spawning season of Pacific cod was from December to March, and the main spawning season was from January to February, and the period of the spawning season was longer for males than the females. The diameter of the matured oocytes was 0.80-1.10 mm with a single mode of 0.95 mm. Fecundity was 1,300,000-9,400,000 in total length of 65-95 cm and the relationship between the total length (TL, cm) and fecundity (Fc) was Fc= $180,248\timesTL-10,883,638$. The total length at first maturity was observed at 57 cm for females and 47 cm for males. The size at $50\%$ group maturity was estimated to be 63.9 cm for females and 56.0 cm for males.

• 한국수산과학회지
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• 제54권1호
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• pp.46-52
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• 2021

The maturation and spawning of Pacific cod Gadus macrocephalus were inversigated using 2,415 samples collected monthly from January 2017 to December 2019, in the Yellow Sea of Korea. We analyzed monthly changes in gonadosomatic index (GSI), maturity stage, egg diameter (mm), the relations fecundity and total length (cm). The spawning period was February to March. Fecundity varied between 334,836 and 2,099,600 eggs. The relationship between the fecundity and TL of fish was expressed in F=186.86TL2.0954 (R2=0.7359). The percentage of sexually mature females estimated from a logistic function was over 50%, 75% and 97.5% for the size (TL) 39.3, 44.8 and 57.7 cm.

• 천문학회지
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• 제55권3호
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• pp.75-86
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• 2022

The lunar surface progressively darkens and reddens as a result of sputtering from solar wind particles and bombardment of micrometeoroids. The extent of exposure to these space weathering agents is frequently calculated as the location in a diagram of reflectance at 750 nm vs. 950 nm/750 nm color (R-C). Sim & Kim (2018) examined the R-C trends of pixels within ~3,500 craters, and revealed that the length (L) and skewness (s) of R-C trends can be employed as a secondary age or maturity indicator. We broaden this research to general lunar surface areas (3,400 tiles of 0.25° × 0.25° size) in 218 mare basalt units, whose ages have been derived from the size-frequency distribution analysis by Hiesinger et al. (2011). We discover that L and s rise with age until ~3.2 Gyr and reduce rather rapidly afterward, while the optical maturity, OMAT, reduces monotonically with time. We show that in some situations, when not only OMAT but also L and s are incorporated in the estimation utilizing 750 & 950 nm photometry, the age estimation becomes considerably more reliable. We also observed that OMAT and the lunar cratering chronology function (cumulative number of craters larger than a certain diameter as a function of time) have a relatively linear relationship.