AsianScientist (Mar. 16, 2016) – A research group based in Japan has shown that measuring quantities of fish DNA in seawater can reveal how many fish inhabit that environment.
This discovery could enable quicker and more effective surveys of fish distribution, and has potential applications in long-term monitoring. The findings were published in PLOS ONE.
Until now, the distribution of marine species was calculated using two main methods: fish capture and fish finder equipment. However, these survey methods involve heavy costs in time and manpower, and specialist knowledge is required to use the measuring apparatus.
On the other hand, a method was already available for determining whether the target fish inhabit a certain area of water: analysis of the fish DNA released into the water.
The research team, led by Satoshi Yamamoto, a research fellow at the Kobe University Graduate School of Human Development and Environment, took this a step further, testing whether it was possible to discover the location of fish and size of their schools by measuring the amounts of environmental DNA, or eDNA, released into the environment.
In June 2014, they collected one-liter samples of surface water and bottom water from 47 locations in Maizuru Bay in the city of Maizuru and estimated the concentration of eDNA of Japanese jack mackerel using real-time polymerase chain reaction (PCR) technology. They then compared the eDNA concentration in the 47 locations with the biomass of Japanese jack mackerel that was simultaneously measured using fish finder equipment.
They discovered that the eDNA concentration of a location reflected the biomass within 10-150 meters of the location. This proves that environmental DNA reflects the biomass of the target fish species, and environmental DNA analysis methods can be used to quantitatively measure the distribution and school size of saltwater fish.
This method is simple, requires no specialist knowledge, and can be used for large-scale surveys over a short period of time. These features also make it suitable for long-term monitoring. The method has the potential to drastically improve efficiency for surveys of the amount and distribution of marine resources.
The article can be found at: Yamamoto et al. (2016) Environmental DNA as a ‘Snapshot’ of Fish Distribution: A Case Study of Japanese Jack Mackerel in Maizuru Bay, Sea of Japan.
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Source: Kobe University; Photo: Shutterstock.
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