Age,growth and age at sexual maturity of fan ray <Emphasis Type="Italic">Platyrhina sinensis</Emphasis> (Batoidea: Platyrhinidae) in Ariake Bay,Japan |
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Authors: | Gen Kume Keisuke Furumitsu Atsuko Yamaguchi |
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Institution: | Landcare Research, Lincoln 7640, New Zealand,;Graduate School of Science and Technology, Nagasaki University, Bunkyo, Nagasaki 852-8521, and;Faculty of Fisheries, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan |
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Abstract: | Abstract: Age, growth and sexual maturity of the fan ray Platyrhina sinensis in Ariake Bay, Japan were determined from specimens collected from May 2002 to September 2006. Age determination was conducted by vertebral centrum analysis using soft X-radiography. Annual band pair deposition was determined by marginal increment and edge analyses. The von Bertalanffy growth model best described the overall pattern of growth for both males and females (males L ∝ = 455.2, k = 0.56, t 0 = ?1.09; females L ∝ = 555.8, k = 0.28, t 0 = ?1.77; L ∝ is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t 0 is the theoretical time at zero length). Parameter estimates suggest that females attain a larger asymptotic total length and grow more slowly than males. The observed maximum ages were 5 years for males and 12 years for females. Age at 50% sexual maturity was 2.1 years for males and 2.9 years for females. The results indicate that this species is relatively fast-growing, short-lived and early maturing compared with many batoid species. |
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Keywords: | age at sexual maturation age determination Ariake Bay elasmobranch life history |
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