DNA analyses enable more precise identification of fish species
Published: Tuesday, Dec 5th 2023, 08:20
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Identify fish species in a river using DNA traces: This method was tested at 89 locations in Switzerland. It proved to be simpler and more reliable than the electrofishing method used to date.
This was the conclusion of a large-scale study, as announced by the Swiss National Science Foundation (SNSF) on Tuesday.
According to the SNSF, electrofishing, which has so far been used to control fish stocks, involves stunning the fish with electricity and then collecting them. Electrofishing, which is harmful to fish, is only permitted in Switzerland for scientific purposes.
According to the SNSF, fish population monitoring has therefore only been carried out selectively to date, usually every five years. "Meaningful monitoring of biodiversity is not possible in this way," study leader Florian Altermatt from the University of Zurich and the aquatic research institute Eawag was quoted as saying in the press release. In addition, the animals were only identified based on their appearance using this method.
Dander and excrement
The environmental DNA method involves searching for traces of DNA in the water. Fish leave these behind via skin scales or excrement, for example. The researchers took two liters of water from each body of water and collected the environmental DNA from it. By comparing the genetic sequences with a comprehensive database of fish DNA, the species could be identified.
They compared the results with records from the last 30 years at the respective locations, as well as with electrofishing results. The results were consistent with the historical data on the one hand and showed a greater diversity of species than would have been expected from selective electrofishing on the other.
"Using the environmental DNA, we were also able to identify fish that live further upstream, as well as species that are difficult to catch using the electrofishing method," explains Altermatt. The results of the study, which was co-financed by the Federal Office for the Environment (FOEN), were published in the "Canadian Journal of Fisheries and Aquatic Sciences".
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