• Journal of Forest and Environmental Science
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• v.39 no.2
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• pp.73-80
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• 2023

Little is known of the life history of Garcinia kola; the objective of this study, therefore, was to assess the fruiting age and tree size of the species in a coastal humid tropical climate plantation condition. A total 103 trees were used in the study viz; 80 ten-year-old trees at reproductive maturity onset and 13 thirty-year-old trees with several cycles of reproduction that constitute two independent variables. Data collected were age of onset of flowering and size at reproductive maturity onset. Relative size at reproductive maturity onset (RSOM) was estimated as size at reproductive maturity onset (SOM) divided by asymptotic maximal size (AMS). Data analysis was conducted using pairwise t-test and principal component analysis (PCA). Reproductive maturity onset (flowering) was recorded in the ten-year-old stand eight (8) years after planting. Mean size at reproductive maturity onset (SOM) was height 5.32±1.7 m, dbh 0.11±0.03 m, total number of branches was 29.6±7.3, crown depth 5.24±1.05 m, crown diameter was 4.78±0.7 m, branch diameter 0.098±0.01 m, leaf length 0.13±0.02 m, leaf breadth 0.37±0.01 m, twig length 0.35±0.11 m and leaf per twig 6±0.84 and asymptotic maximal size (AMS) was height 19.85±0.76 m, dbh 0.95±0.09 m, total number of branches 62±5, crown depth 18.83±0.7 m, crown diameter 12.5±1.64 m, branch diameter 0.5±1.6 m, leaf length 0.16±0.023 m, leaf breadth 0.45±0.12 m, twig length 0.37±0.11 m and leaf per twig 19±7.5. Pairwise t-test analysis showed there was significant differences between SOM and AMS in all growth factors except leaf length, leaf breadth, and twig length. Highest relative size at reproductive maturity onset (RSOM) was recorded in leaf length 0.82, twig length 0.82, and leaf breadth 0.80, while, the lowest was branch diameter 0.11. Four components out of the total of eleven were extracted to explain the relationship in RSOM: Principal component one (PC1) explained 37.23%; PC2 26.4%, PC3 22.73%, and PC4 13.64%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.3
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• pp.235-243
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• 2024

Researching and estimating the ecological characteristics of target fish species is crucial for fisheries resource management. The results of these estimates significantly influence stock assessments and management reference points such as size limit and closed seasons. Recently, ecological characteristics have been changing due to overfishing, climate change, and marine pollution, making continuous estimation and monitoring essential. This study analyzed the ecological changes in small yellow croaker (Larimichthys polyactis) resources in Korea over 24 years (2000-2023) using biological data (growth and gonad traits). By estimating the annual length-weight relationship and length at maturity (L50 and L95), we interpreted the numerical trends of early maturation due to resource depletion. The parameter b of the length-weight relationship, indicating the nutritional status of the resources, showed a slight increase over the years, suggesting relatively good nutritional status (b > 3.0) during most periods. Trend analysis between length at maturity and biomass indicated that as biomass decreased, maturity length also decreased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.318-328
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• 2021

We investigated the maturity and spawning of the brown sole Pseudopleuronectes herzensteini, in the coastal waters of the East Sea off Gangwon and Gyeongbuk, South Korea, using samples collected by gill net and longline fishery from January 2018 to December 2019. We analyzed oocyte development, monthly maturity stage, gonadosomatic index (GSI) and total length at maturity. Histological analysis of ovarian development in P. herzensteini revealed that the development was group-synchronous. The spawning peak in Gangwon and Gyeongbuk occurred from April to May and from February to March, respectively. Thus, the spawning season in Gangwon was 1-2 months later than that in Gyeongbuk. The length at 50% maturity for females was estimated as 24.2 cm and 19.0 cm in Gangwon and Gyeongbuk, respectively. Similarly, the length at 50% maturity for males was estimated as 19.8 cm and 16.5 cm in Gangwon and Gyeongbuk, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.113-117
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• 2006

To identity the effect of sowing dates on flowering and maturity of sesame, some agronomic traits including days to flowering and days to maturity were investigated under five different sowing dates. Plant height, days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant were showed significantly different by years, sowing dates and varieties. Interaction between sowing dates and varieties affected to days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant. Plant height, days to flowering and days to maturity decreased significantly as sowing dates were delayed, but number of capsules and seed weight per plant showed highest at the sowing date of May 10. At the regression analysis of shortness degree of growth period by the response of days to flowering and days to maturity under different sowing dates, sesame varieties with earlier flowering habit were much less affected by day length rather than ones with later flowering habit. $R^2$ and gradient value on the days to maturity regression graph were smaller indicating that maturity was much less sensitivity than flowering to the change of day length and temperature in the move of sowing dates. Therefore, it would be concluded that early maturity sesame varieties have higher potential adaptability to various sesame cropping systems in view of their less sensitivity to day length changes under different sowing dates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.9-18
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• 2020

We investigated the maturity and spawning dynamics of chub mackerel Scomber japonicus in Korean waters using samples collected by a large purse seine fishery from January 2013 to December 2017. We analyzed sex ratio, monthly maturity stage, gonadosomatic index (GSI), Fulton's condition factor (K), and fork length at 50% group maturity. Spawning occurred from March to June, with a peak in May. We detected a significant difference in sex ratio (χ² test, P<0.05). The relationship between fork length and body weight was expressed as BW=0.0025FL^3.4693. We estimated 50% group maturity at a female fork length of 29.3 cm.

• Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.350-356
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• 2022

This study aims to estimate the smallest size of mature individuals that can be exploited. Fish samples of Coryphaena hippurus were collected from Kalinaun fishermen's catches in the Molucca Sea. They were sexed, then the fork length (FL) and maturity stage were recorded. Results showed that C. hippurus in the Molucca Sea had a sex ratio of 1:1.94 (p < 0.05). Males had a length range of 499-831 mm FL and females were in the length range of 481-813 mm FL. Size at first maturity was estimated as 529 mm FL for males with a range of 475-588 mm FL and 405 mm FL for females. This study provided basic information for future management needs of the dolphinfish, especially in the Molucca Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.19-26
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• 2020

The maturity and spawning of pacific sand eels Ammodytes japonicus, was investigated using samples collected by gill net in coastal waters near Donghae, Gangwon-do, from January 2017 to December 2018. Monthly changes were analyzed in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity (F), and total length (TL) at 50% group maturity. The average TLs of female and male A. japonicus were 18.5 and 18.1 cm, respectively. The spawning period was from November to March, with the peak from December to February based on monthly changes in GSI and maturity stages. The egg diameter during the spawning-capable stage was 300-1000 (main mode 500-600) ㎛. Fecundity ranged from 6,411 eggs at 16.7 cm fork length to 45,771 eggs at 24.7 cm fork length. The relationship between TL and F was F=0.00005TL^4.2715 (R²=0.7216), such that F increased with TL. TL at 50% group maturity was estimated to be 15.1 cm for both sexes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.367-375
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• 2016

Marbled flounder Pseudopleuronectes yokohamae is a commercially important flatfish in the coastal waters of the East Sea off Pohang, Korea. Maturity and spawning dynamics of P. yokohamae were investigated based on samples collected by gill net and long line in the coastal waters off Pohang from January 2013 to December 2014. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length at 50% group maturity. We found that the spawning period was December to February, wherein fecundity ranged from 55,760 eggs at 20.40 cm total length (TL) to 1,559,007 eggs at 46.6 cm TL. The relationship between TL and fecundity (F) was F = 0.0017 TL^3.5604 (R² = 0.6984), and F increased with increasing TL. We estimated the TL at 50% group maturity as 27.4 cm for female and 23.5 cm for male P. yokohamae, respectively. The results from this research will aid in the development of policies on season and minimum catch length for sustainable production of P. yokohamae. We propose that it is necessary to conduct long-term ecological monitoring for this species because biological properties such as spawning ecology and growth performance are being affected by climate change.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.449-458
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• 2013

This study investigated purplish Washington clam, Saxidomus purpuratus on its gonadal development, reproductive cycle and shell length (age) at 50% female group maturity from January to December 2011 in Jinhae Bay, Korea. This species is dioecious. The gonad index (GI) began to increase in January, reached the maximum value in May and to decrease in June, reached the minimum value in September then to increase slowly in October again. The reproductive cycle of the clams can be divided into five successive stages: the early active stage (Ea, from February to March), the late active stage (La, from January to March and October to December), the ripe stage (R, from January to May), the spawning stage (S, from June to December) and the degenerative and inactive stage (Ia, from January to February and November to December). The spawning periods were from June to December and the main spawning periods were from July to October. The shell length at 50% female group maturity (SL50) was estimated to be 63.6 mm, which can be converted as sexual maturity age of 2.2 year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.103-106
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• 2020

We investigated the biological maturation of blackthroat seaperch Doederleinia berycoides in southern Korea waters, based on samples collected from March 2018 to February 2019. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI) and total length (TL) at 50%, 75% and 97.5% group maturity. The spawning period was May to October in 2018. We estimated the TL at 50% group maturity as 27.0 cm for females in 2018. We estimated the TL of females at 75% and 97.5% group maturity as 28.7 cm and 32.7 cm, respectively, in 2018.