Article ID: 21-00020
While social demands for understanding the current status of biodiversity and for its conservation are increasing, biodiversity in river ecosystems may be decreasing rapidly. The importance of setting targets and goals when restoring and rehabilitating ecosystems has been pointed out, and one effective method is to use information on past species distributions. Then, we identified a list of "lost species" of freshwater fishes that have never been found since 1990, although they were recorded in 1978, by organizing the National Survey on Natural Environment conducted in 1978 and the ongoing census as the National Census on River Environments since 1990. We compared the results of the two surveys in 102 of the 109 class A river systems and found that native fishes recorded in 1978 but not collected since 1990 were two species, Pungitius sp. (Musashitomiyo) and Aphyocypris chinensis (Hinamoroko). In 39 river systems, all the native species recorded in the National Survey on Natural Environment were collected in the National Census on River Environments. However, for 63 river systems, one to ten species/species groups were not collected, and these species in each river system were listed as a list of "lost species". This list contained various species, such as diadromous and peripheral as well as pure freshwater fishes, including also many common species not listed in the national Red Lists. The species listed on our "lost species list" are not necessarily extinct, but should be endangered. Therefore, in each river system, confirmation of the presence/absence of the listed species and implementing conservation measures for them are needed before they become locally extinct. In addition, it will be possible to set clear targets and goals for the restoration and rehabilitation of river ecosystems based on information on the habitat and life history of these fish species.
