The Science behind the Fight against Invasive Species
BY MATTHEW PETASEK, GREEN BAY FWCO
for Silver and Bighead carp DNA analysis. Credit: USFWS
Aquatic invasive species are a serious threat to any waterbody, in the Great Lakes, fish and wildlife agencies throughout the region have documented more than 180 invaders. This fact is one of the many reasons why the US Fish and Wildlife Service has been tasked with monitoring for any potential invaders that we have not seen yet. At the top of our priority list are the Silver and Bighead carps, collectively known as bigheaded carps, which have been taking the country by storm since the 1970’s; particularly in the Midwest region. Since bigheaded carps have been established in the Mississippi and Illinois rivers for a long time, it’s clear that we have to look ahead and consider the security of the Great Lakes against such a prolific invader. So far, efforts have been successful in stopping their spread with the use of electric barriers in the Chicago Area Waterway System; however, we are still continually monitoring in Lake Michigan for any signs of an invasion. One of the primary methods we use to monitor for Silver and Bighead carps is environmental DNA (eDNA).
Environmental DNA can be anywhere throughout the waterways attached to the organic material found there. The Fish and Wildlife Service collects thousands of water samples every year from rivers that have been identified as suitable staging or spawning habitat. The water samples are then sent to a genetics laboratory where it is processed to find traces of fish DNA; in this case, Silver and Bighead carps. The month of May marked the first round of eDNA sampling for the Green Bay Fish and Wildlife Conservation Office’s AIS team. This office has been responsible for monitoring the St. Joseph, Kalamazoo and Grand Rivers in Michigan as well as the Fox and Milwaukee Rivers in Wisconsin. The Green Bay office’s team of 10 people spends weeks planning and as many as eight days in the field to collect and prepare these water samples for analysis; and that’s just for one round.
So far, the team has collected a total of 840 samples from these five high-priority rivers. This is only one third of the samples that the Green Bay team plans to collect this season, and only about 10% of the total samples that will be taken in all of Region 3. While results won’t be in for some time, all Region 3 AIS teams continue to monitor their respective watersheds for signs of aquatic invasion. The Great Lakes region should feel better knowing that the US Fish and Wildlife offices are all working together towards a common goal; protecting the world’s largest freshwater resource from aquatic invasive species such as bigheaded carps.