Using DNA to identify fish in the sea

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Using DNA to identify fish in the sea

January 30, 2017 - 19:08
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Japanese researchers have developed a new method of identifying multiple fish species by analysing DNA in seawater samples.

Researchers collecting water samples.

This technology involves the use of environmental DNA metabarcoding, a method which identifies fish species by collecting and analysing the DNA released by fish in the seawater (called environmental DNA or eDNA). Multiple species can be detected using this method.

So far, this method has proved to be accurate and more effective than marine surveys that relied on observation or capturing the fish, which required a lot of manpower.

Until now, eDNA analysis has only been tested in areas with a limited numbers of fish species. In areas that are home to many difference fish species, its effectiveness had not been verified because the data collected via traditional methods is limited, so a proper comparison could not be made.

However, after only one day of eDNA metabarcoding in Maizuru Bay in Kyoto prefecture, the research team achieved positive results. Using this method, they were able to detect 128 fish species from seawater samples. Among the 128 species were more than 60 percent that had been observed during 140 visual surveys that spanned 14 years. (If one excluded the fish species that had only recently migrated to Maizuru, it would have been a nearly 80 percent match.)

In addition, the researchers also managed to identify fish species that could not be confirmed by visual observation, as well as certain varieties of fish larvae that were difficult to identify visually.

Even in areas with many fish species, eDNA metabarcoding enables the area to be surveyed within a short time period. As such, this method can be used to monitor the invasion of foreign species across large areas, to conduct surveys of fish distribution in hard-to-access areas or where it is forbidden to collect specimens.

This research was carried out as part of the Japan Science and Technology Strategic Basic Research Programs.

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