Abstract
For protecting endangered species, precise understanding of their distribution is crucial. However, it is often very difficult to estimate at a large scale with conventional methods (e.g., casting nets or electrofishing for aquatic species) because of their low densities in the wild. Sakhalin taimen (Parahucho perryi) is one of the largest and most critically endangered freshwater salmonid fishes in the world. In this study, we applied an environmental DNA (eDNA) detection system for this species to 120 rivers in Hokkaido, the second largest main island of Japan. We successfully detected eDNA from Sakhalin taimen in seven rivers (5.8%). Although these rivers were widely distributed across the island, more than 95% of the total amounts of eDNA were detected from region-A and -I, indicating that local populations in the other regions of Hokkaido are very small and on the brink of extinction. In addition, principal component analyses based on the eDNA-based estimation of Sakhalin taimen distribution and GIS revealed their distribution determinants including limited topographic relief of watershed as well as presence of wetlands and lagoons. Our results suggest that eDNA-based detection systems are an efficient means of monitoring the population status of endangered freshwater species at large scales.
Highlights
Precise information about the current distribution and biomass of threatened species is essential for their conservation and appropriate management
We aimed to estimate the distribution and population status of Sakhalin taimen in 120 rivers covering the entirety of Hokkaido, Japan, using an environmental DNA (eDNA) detection system established during a previous study (Mizumoto et al, 2018)
We looked into the same variables that were tested in Fukushima et al (2011) to confirm the current population status of Sakhalin taimen
Summary
Precise information about the current distribution and biomass of threatened species is essential for their conservation and appropriate management. While many kinds of threats are considered as factors for extinction (e.g., loss or degradation of habitat, illegal trade, invasive species, or human activity), 85% of the endangered species are facing threats of habitat loss or degradation (Wilcove et al, 1998). Specialized skills are typically needed for species identification, especially in the case of Sakhalin Taimen Distribution in Japan juveniles. Due to these requirements, studies on current distribution of endangered species are often incomplete and may be limited to small parts of a species’ distribution
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