| A. longipinnis is endemic to Japan and designated as natural monument while its distribution is rather patchy and population viability is in serious doubt. Bitterling fish spawn in live unionoid mussels， remains， and hatch inside mussels during their development periods till emerging as larvae(i.e.，parasitism or commensalism). Floodplain water bodies(FWBs)， which are either connected to or isolated from the main channel， provide one of major habitat for bitterling fish. Deteriorations of floodplain habitat are manifested after 1970s as a result of riverbed degradation and concurrent floodplain terrestrialization. Thus， there is an urgent need to understand habitat requirements of A. longipinnis， including host mussel distribution， and habitat stability， to develop effective habitat restoration strategies. We examined distribution of A. longipinnis and measured physical habitat environment in 104 FWBs. Occurrence of A. longipinnis were predicted in FWBs having large surface area， abundant mussels， high connectivity to neighboring FWBs， and being sheltered from flood shear stress. With habitat and species distribution relationships， restoration strategies for A. longipinnis are discussed with some sites being planned for or already manipulated with experimental treatments. |
