The pattern of absolute growth of a freshwater crab Geothelphusa dehaani (White) was studied in a natural population inhabiting the Taniyamagawa River, Fukuoka, Japan. Samples were collected from September 1990 to September 1991. Cohorts were distinguished by fitting Gaussian distributions to the monthly size frequency distributions of the carapace width (CW) of both sexes. Pauly and Gaschütz's equation was applied to changes of the mean CW of cohorts. Crabs hibernate from December to March at this field site. Individuals which were active or in a state of molting were not observed in the samples over this period. Juvenile crabs showed limited growth in the year of hatching. After the initial winter, the crabs repeatedly molted two or three times in a year. We estimate that the minimum size of maturity is about 19mm CW in females and about 18mm CW in males and maturity occurs at about four years old.
Mendeley出力
