2024 Volume 18 Pages 93-105
A stickleback Pungitius sp., named “Musashi-tomiyo”, is an endemic species that originally ranged across spring-fed streams in the Kanto region, eastern Japan. The species’ population has dramatically decreased due to habitat degradation and water pollution over the past decades. Currently, the last remaining wild population is found only in the upper reaches of the Moto-Arakawa River in Kumagaya, the northern part of Saitama Prefecture. Although the species is protected by prefectural law, the population dynamics have fluctuated largely and abundances estimates outside the preserved area have now declined. Therefore, conservation concerns for the wild population of this species have grown. We surveyed the distribution, relative abundance and habitat conditions of the threatened stickleback in areas outside of preserved habitats. We found that the sticklebacks were abundant in habitats with rich aquatic vegetation cover and a relatively close proximity to an inflow of groundwater. We also found that water temperatures, depths and velocities were stable for the studied period, while invasive red-swamp crayfish Procambarus clarkii was in relatively low density. We concluded that the habitat conditions at this site might be suitable for the survival and reproduction of the stickleback.
