Fish fauna around the habitat of the endangered loach Parabotia curtus and prospects for restoring extirpated areas.

Abstract

Ayumodoki (Parabotia curtus), a critically endangered loach, survives only in three locations in western Japan. Its population in Yagi, Kyoto Prefecture, went extinct in the wild in the 1990s but has been maintained in captivity for over 40 years. This study investigated fish fauna in the areas including the former and nearby current habitats primarily using environmental DNA metabarcoding. We detected 41 freshwater fish species from 26 sites, but P. curtus was found only in its known habitat in Kameoka. However, the species composition suggests that re-establishing the population in the Yagi former habitat is feasible if spawning habitats and migration routes are improved. Adequately maintaining the captive population and enhancing the local environment are crucial for successful reintroduction.