児島湖産テナガエビの成長と寿命

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An estimation of the population growth and life span of the Oriental river prawn Macro-brachium nipponense was carried out. 17, 541 prawns were collected in Lake Kojima, Okayama Prefecture. The montly mode of each age group by sex was obtained based on normal distribu-tion, using a computer analysis technique, from body length histogram, and plotted. According to the monthly ratio of the number of ovigerous females to that of females of 26 mm (Biological minimum size) and larger in body length, the spawning season of the species in-habiting Lake Kojima is from Late May to the middle of September, continuing for almost four months with its peak in July As to the mean growth of this prawn in Lake Kojima, male attains 33 mm in body length and 0.7g in body weight at one year after hatching out, 45 mm and 2.0g at two years, 61 mm and 5.1g at three years, and 63 mm and 5.6g in the perishing winter period. Female grows to 28 mm and 0.5g at one year, 47 mm and 2.3g at two years, and 57 mm and 4.1g in the perishing winter. For male's life span 3 years and 4 to 9 months is estimated, while that of female may be 2 years and 4 to 10 months when presuming they hatch out in the middle of Juiy. Considering the mode of the appearance of ovigerous female, it is supposed that female will mature sexually at one year after hatching out, while, judging from the developmental infection point of the second chetiped, male will mature at two years after hatching out, attaining 45 mm in body length. Consequently it is presumable that 1-year-old female and 2-year-old male will show spawning activity for the first time late in July, and male and female will experience the spawning season twice respectively within each life span
日本水産學會の論文

児島湖産テナガエビの成長と寿命

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