Abstract
The habitat network and distribution of Eusphingonotus japonicus was investigated along the middle reaches of Tama River. There were 39 habitats lived contiguously in the Tama River. It was confirmed from the result of mark-release-recapture that 85 of 4641 marked individuals moved between habitats. Moreover, there was a positive correlation between total population size and the gravelly floodplains area, and there was a negative correlation between the emigrant rate and the gravelly floodplains area. Buffer-1 of 300m that E. japonicus could move fragmently and buffer-2 of 810m thar was considered the maximum value for emigrant were generated in each habitat. From the result, It was inferred that regional population was greatly divide into of 52.6 to 53.2km from estuary. Therefore, itis importanto connect the fragment regional population in order to conserve the habitat of E. japonicus in middle reaches of Tama River.
