• Title/Summary/Keyword: Length at maturity

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Reproductive Biology of the Washington Clam Saxidomus purpuratus in the Coastal Waters of Yeosu, Korea (한국 여수에 서식하는 개조개(Saxidomus purpuratus)의 산란생태)

  • Da Yeon Kang;Seong Yong Moon;Kyung Mi Jung;Gun Wook Baeck
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.57 no.1
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    • pp.53-59
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    • 2024
  • The reproductive biology of the Washington clam Saxidomus purpuratus, from Yeosu, Korea was investigated based on 699 individuals collected from January to December 2022. The sex ratio of this species was not significantly different from a 1:1 (male:female) sex ratio (P>0.05). Monthly changes in gonadosomatic index were analyzed to estimate the spawning season. The reproductive cycle of this species can be divided into the following stages: active (Jan.-Mar.), ripe (Mar.-Nov.), spent (Apr.-Dec.), and degenerative (Jun.-Dec.) stages. The spawning period ranged from March to December with the main periods being from April to June and from September to November. The shell length at 50% female group maturity (SL50) was estimated to be 60.2 mm.

Studies on the Propagation of the Freshwater Prawn, Macrobrachium nipponense (De Haan) Reared in the Laboratory 2. Life History and Seedling Production (담수산 새우, Macrobrachium nipponense (De Haan)의 증${\cdot}$양식에 관한 생물학적 기초연구 2. 생활사 및 종묘생산에 관한 연구)

  • KWON Chin-Soo;LEE Bok-Kyu
    • Journal of Aquaculture
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    • v.5 no.1
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    • pp.29-67
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    • 1992
  • Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.

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Analysis of Gonadosomatic Index (GSI) and Sexual Dimorphism of Coreoleuciscus splendidus in Age Groups (연령에 따른 쉬리 Coreoleuciscus splendidus의 성적이형과 생식소 숙도 분석)

  • Song, Ha-Yoon;Kim, Kyeong-Mu;Shin, A-Ri;Lee, Jin-Seok;Park, Hee-Won;Lee, Wan-Ok
    • Korean Journal of Ichthyology
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    • v.29 no.3
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    • pp.176-189
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    • 2017
  • Age estimation and sexual dimorphism of Coreoleuciscus splendidus were estimated using otolith, length-frequency distribution and 23 morphological measurements, from 245 individuals collected from September 2016, February and April 2017 in the Gapyeong stream, Han River, Korea. Result of age estimation of C. splendidus, we most examined were 2, 3 and 4-age, and the maximum observed ages were 5-age. Nine out of twenty-three morphometric measurements were significantly different between the genders. Anal fin have showing major sexual dimorphism in particular between adult individuals. This sexual dimorphism was based on extension of anal fin soft rays of male individuals. Therefore anal fin of males is always longer and wider than females. During spawning season male individuals possess nuptial tubercles on anal fin rays. However, another measurements and morphological characters does not exhibit sexual dimorphism in the between male and female individuals. The sexual dimorphism was observed to only over 2-years old individuals with sexual maturity. But juvenile and 1-years old individuals do not have sexual dimorphism with sexual maturity. Peak season of spawning was April to May and they start first spawning at 2-age. The ages at major spawning groups were most 3-age, and they maximum GSI index was 14.91 (female), 8.96 (male) at 5-age, respectively.

Mass Reduction and Physicochemical Properties of the Produced Compost during Composting Domestic Food Wastes in a Small Composter (소형 퇴비화용기에서 가정 음식물쓰레기의 퇴비화 과정 중 감량화 및 생산 퇴비의 물리화학적 특성)

  • Park, Ju-Won;Seo, Jeoung-Yoon
    • Korean Journal of Environmental Agriculture
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    • v.20 no.4
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    • pp.238-243
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    • 2001
  • Mass reduction and physicochemical properties of the produced compost were investigated during composting domestic food wastes without additive. A small composter used in this study had the height of 15 cm from the center of bottom half circle (diameter 24 cm) up to under the lid, the side length of 50 cm and the horizontal lid angle of $50^{\circ}$ and was operated at the heating unit temperature of $85^{\circ}$. It was mixed by the rotating arm for two minutes in every half hour while supplied with air flow at 3 L/min for 10 minutes in every half hour. This condition was found in a preliminary experiment as optimal for keeping the water content of composting material in the optimal range without adding any bulking materials. The domestic food wastes were added into the composter at the rate of 1 kg/day without additives during composting. The results were as follows; during the composting process, water content maintained in the range of $51.0{\sim}53.5%$. Hemicellulose and lignin contents did not show any tendency, but cellulose content decreased. During the composting process, $NH_3-N$ and $NO_2-N$ were not detected due to nitrification. The contents of inorganic compounds did not increase during the composting process. They were in the range of $1.32{\sim}1.71%\;P_2O_5$, $1.29{\sim}1.48%\;CaO$, $0.41{\sim}0.49%\;MgO$, and $0.38{\sim}0.74%\;K_2O$. For 20 days, weight reduction rate was 67.5% in wet basis, and decomposition rate was 48% in dry basis. Concentration of heavy metals (Cu, Cr, Cd, Pb, Zn, Hg, As) was less than the limiting value of the compost. Maturity of the produced compost was 3 grade through reaching maximum temperature of $46{\sim}48^{\circ}C$.

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Reproduction of the Goby Fish Periophthalmus magnuspinnatus in Mud Flat of Suncheon Bay, Korea (한국 순천만 갯벌지역 큰볏말뚝망둥어(Periophthalmus magnuspinnatus)의 생식)

  • Kim, Jae-Won;Yoon, Yang-Ho;Shin, Hyun-Chool;Takita, Toru;Kim, Ji-Hyung;Park, Se-Chang;Park, Chan-Il;Baeck, Gun-Wook
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.41 no.4
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    • pp.289-293
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    • 2008
  • Reproduction of the goby fish Periophthalmus magnuspinnatus was examined using 298 specimens collected from April to October 2005 in a mud flat of Suncheon Bay, Korea. Specimens ranged in body length(BL) from 1.3 to 9.1 cm. The gonadosomatic index(GSI) of females was highest in June and decreased until August. The hepatosomatic index(HSI) and fatness index of females were high in April and then decreased to nadirs in July. Spawning season lated from April to August and the ratio of females to males did not significantly differ($x^2$-test, p>0.05). The first spawning length was 4.5 cm BL, and the size of 50% maturity was estimated at 4.98 cm BL. Fecundity(F) ranged from 1,316 to 4,768 eggs, and the relationship between F and BL was estimated as $F=0.1562BL^{1.4068}(R^2=0.59)$.

Growth, Maturation and Development of Sargassum fulvellum (Sargassaceae, Phaeophyta) (모자반(Sargassum fulvellum)의 생장, 성숙과 발생)

  • HWANG Eun Kyoung;BAEK Jae Min;PARK Chan Sun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.38 no.2
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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 $80{\mu}mol/m^2/s$.

Reproductive ecology of the sharp toothed eel in the southern Korean waters (한국 남해에 서식하는 갯장어, Muraenesox cinereus (Forsskal)의 생식생태)

  • Cha, Hyung Kee;Seo, Young Il;Oh, Taeg Yun;Kim, Heeyong;Lee, Sun Gil;Choi, Mun Sung
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.48 no.3
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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).

Reproductive Characteristic of Gluttonous goby, Chaenogobius gulosus in the Coastal Waters of Tongyeong, Korea (통영 주변해역에서 출현하는 별망둑(Chaenogobius gulosus)의 산란 특성)

  • Baeck, Gun-Wook;Jeong, Jae-Mook;Park, Joo-Myun;Huh, Sung-Hoi
    • Korean Journal of Ichthyology
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    • v.23 no.4
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    • pp.300-304
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    • 2011
  • The reproductive characteristics of Chaenogobius gulosus was examined using 333 specimens collected monthly between October 2008 and September 2009 in the coastal waters of Tongyoung, Korea. Specimens ranged from 2.0 to 12.6 cm in standard length (SL). The gonadosomatic index (GSI) of females was highest in February and decreased until April, with the spawning season lasting from December to April. The monthly ratio of female to male did not significantly differ (${\chi}^2$-test, p>0.05). The size at 50% maturity for females was 7.9 cm SL. Fecundity ranged from 1,112 to 6,059 eggs, with a mean of 3,011 eggs.

Mesh selectivity of gill net for female Japanese sandfish (Arctoscopus japonicus) in spawning season (산란기 도루묵(Arctoscopus japonicus) 암컷의 자망에 대한 망목선택성)

  • Park, Hae-Hoon;Jeong, Eui-Cheol;Bae, Bong-Seong;Yang, Jae-Hyeong;Chol, Soo-Ha;Lee, Sung-Il
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.43 no.4
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    • pp.274-280
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    • 2007
  • The mesh selectivity of gill net for Japanese sandfish (Arctoscopus japonicus) caught in the East Sea, Korea was described. The experiment was conducted with five different kinds of mesh size (39.4, 45.5, 51.5, 53.0, 57.6mm) between November and December 2006 in spawning season. The catch was mostly Japanese sandfish (93.3%) and some others (6.7%), and almost all of the female Japanese sandfish were larger than the fork length at 50% maturity (16.7cm). The selection curve for the female Japanese sandfish caught from the experiments was fitted by the Kitahara's method to a polynomial equation which was $s(R)={\exp}\{(0.2584R^3-5.3445R^2+32.269R-59.868)-0.6585\}$ where R=l/m, and l and m are fork length and mesh size, respectively.

Catch and reproductive biology of common octopus Octopus vulgaris in the coastal waters of Jeju Island, Korea (제주해역 참문어(Octopus vulgaris)의 어획실태와 생식생태)

  • HAN, Song-Hun;KO, Jun-Chul;KIM, Min Sun;KIM, Bo-Yeon;CHOI, Jung Hwa
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.58 no.2
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    • pp.113-120
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    • 2022
  • The purpose of this study is to provide information about annual variations in catch size and changes in reproductive biology in the common octopus, Octopus vulgaris, a commercially important species in Jeju Island. Samples were collected from coastal waters of Jeju Island, Korea by coastal trap fishery from January to November 2021. Octopus vulgaris have been decreasing in this region since 1984. The mantle length (ML) ranged from 4.5 to 17.8 cm and body weight (BW) ranged form 88.5 to 2,657.5 g. A χ2-test revealed that the number of males was significantly greater than females (χ2 = 32.712, df = 10, P<0.05). Mature females were found from January to July and male occurred January to August. The gonadosomatic index value was higher from July to August than other months. The relationship between mantle length and body weight was BW = 2.4527ML2.3139 (female) and BW = 2.6785ML2.3159 (male). At 50% group maturity, female and male average weight was estimated to be 554.7 g and 330.6 g, respectively.