2020 Volume 22 Issue 2 Pages 125-131
The habitat environment over winter for the female signal crayfish carried eggs with radio transmitters was investigated by using a mark-recapture method in a small river on Bihoro, Hokkaido. This kind of information could make increasing the efficiency of the disinfestation of the invaded signal crayfish if the female carried eggs gathered over winter and disinfested intensively. At the same time, we developed the method to identify the area of the radio source by piloting the drone with a radio receiver over the river, i.e., drone telemetry. Three crayfishes with radio transmitters were released in October 2017, and the habitats over winter for all three crayfishes were pinpointed and recaptured in December 2017. All crayfishes were found in the soil under 60-90 cm away 1-2 m from the riverbank in meandering sections. The environment of habitat over winter was considered to spread throughout the flood channel such inter meandering section. Therefore, it seemed to be practically impossible that we would capture the female lobsters carried eggs in winter, intensively. On the other hand, certain methods of the radio wave source with a drone been shown that there were also effective in soil and water, were expected future applications.
