An environmental DNA (eDNA) technique, which utilizes DNA from water samples to identify vertebrate species in the wild, was first reported in 2008. Since then, the technology has developed drastically all over the world. This new technique provides for strong detectability of rare or alien species. It is especially useful because the basic information (ex. habitats, behaviors, or niches) of these kinds of species is often unclear. Furthermore, this eDNA technique reduces sampling efforts, making it easier to take replicates or track seasonal changes. Despite these benefits, there are some problems for quantifying the biomass of target species using this technique, so it is still an impractical tool for detecting the distribution and biomass at the same time.
In the Sarufutsu river, we collected water samples and set-up sonar equipment for counting adult Sakhalin taimen (Parahucho perryi) during their spawning seasons. For this presentation, we will show the results of stationary sampling for Sakhalin taimen in this river and we will discuss the applicability of eDNA techniques for monitoring temporal distribution and biomass simultaneously by comparing the amount of detected eDNA and the number of fish.