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Wednesday, January 7, 2015
Only 1 of 500 Mississippi River samples test positive for invasive carp
Water samples from southeastern Minnesota pools of the Mississippi River that were collected in August and analyzed in December indicate only a small presence of bighead carp eDNA, according to the Department of Natural Resources.
The U.S. Fish and Wildlife Service, in consultation with the DNR, conducted the environmental DNA (eDNA) sampling and analyzing for invasive carp.
A total of 500 samples were tested for both bighead and silver carp DNA in Pool 5a near Winona, Pool 6 in Winona and pools 8 and 9 near the Iowa border. One sample in Pool 8 tested positive for bighead carp, while none of the samples tested positive for silver carp. Results can be viewed on the USFWS Web page: www.fws.gov/midwest/fisheries/eDNA.html.
“The lone positive bighead result appears to support historical, physical catch evidence of low numbers of invasive carp in this stretch of the Mississippi River,” said Nick Frohnauer, DNR invasive fish coordinator. “Individual captures of adult bighead and silver carp have occurred since 2008 but none were captured in these pools in 2014.”
Environmental DNA is a surveillance tool used to monitor for the genetic presence of an aquatic species. The presence of eDNA does not provide physical proof of the presence of live or dead carp, but indicates the presence of genetic material in the water body. This genetic material may be the result of live carp, or transport of only the genetic material via boats or other means.
This is the first time samples were collected in the southeastern Minnesota pools.
Given the low population size at this time, the DNR and USFWS sampled these pools to help guide future traditional sampling efforts and establish a baseline to begin a time series that will help detect population changes. The plan is to collect samples at these and potentially other pools farther north each year.
“It’s important to remember that eDNA is still a new technology and cannot be used to estimate population size at this time,” Frohnauer said. “But the DNR hopes to use this technology to inform field monitoring efforts.”
The USFWS and the DNR will review eDNA results and advancements along with other 2014 monitoring results in planning 2015 sampling.