2020 Volume 26 Pages 307-312
For recovery of the population of Ayu fish, Plecoglossus altivelis in the lower Tenryu River, we have been continuing sampling of larvae and survey of food mark coverage to estimate their spawning section and feeding section. Number of days when such conventional methods are possible is small, because high turbidity often continues long and it is dangerous to enter the large river channel except when the flow is small. We surveyed environmental DNA (eDNA) of Ayu fish to evaluate whether the highly used sections can be estimated by it and obtained the following findings: 1) the distribution of eDNA concentration in river settlement period shows the similar tendency as that of food mark coverage, 2) eDNA concentration in spawning period is higher in the spawning section estimated from the yolk index of the larvae, 3) eDNA concentration in marine life period is higher in the still water section adjacent to the rivermouth. These results suggest tha eDNA analysis can be an useful substitute for the conventional methods.
