Research groups such as Kobe University, Chuo University, and Kyoto University have revealed that the habitat of Japanese eels in rivers can be estimated from the analysis of the amount of environmental DNA in 1 L of river water.
The Japanese eel, which is widely distributed in East Asia, has been threatened with extinction due to a drastic decrease in its catch since the 1970s.
Data on distribution areas and abundance of resources are indispensable for the conservation of living things.However, in Japanese eels that are widely distributed, it takes a lot of human and time labor to collect and survey using an electric shocker, and eels hidden in vegetation and mud are often overlooked. There was a problem.
Therefore, this research group focused on the usefulness of environmental DNA analysis methods, which have been rapidly developing in recent years.The environmental DNA is the DNA of an organism contained in water, air, soil, or the like, and in the case of water, DNA derived from the excrement of aquatic organisms or the peeled epidermis can be detected.
For verification, the research group drew 10 L of river water at all 125 points in 1 rivers in Japan and measured the amount of environmental DNA of Japanese eels contained therein.At the same time, a collection survey was conducted by an electric shocker at the same site, and the results were compared with the results of environmental DNA analysis.
As a result, environmental DNA of eels was detected in 91.8% of the sites where Japanese eels were confirmed in the electric shocker survey, and environmental DNA was also detected at 35 sites where eels could not be collected due to their low density. bottom.This confirmed that environmental DNA analysis can detect the distribution of eels in rivers with higher accuracy.
Furthermore, since there was a positive correlation between the eel population / biomass obtained in the collection survey and the environmental DNA concentration, it is possible to estimate the eel population / biomass in rivers by examining the environmental DNA. I found.
This result will enable monitoring of Japanese eels in rivers more easily than conventional methods, and is expected to greatly contribute to the conservation of this species' resources.
