By Howard Meyerson
Federal scientists studying the origins of Asian carp DNA found in the Great Lakes, particularly in the Chicago Area Waterway system, ground zero in the politically heated debate about separating Lake Michigan from the Mississippi River Basin, have learned the genetic material can arrive by bird, barge, sewer or other means. Finding DNA today may not mean the dreaded fish are swimming somewhere near.
“I was surprised by how long the DNA can persist, especially in the bird droppings and how long it can persist on really hot surfaces.” said Kelly Baerwaldt, the eDNA program manager for the US Army Corps of Engineers. “When I think about all those barges being pummeled by silver carp and that the stuff (carp slime) can stay on it for a month and still give us the same signal as a live fish, I was really surprised by that.”
Those and other findings were announced two weeks ago by the Army Corps of Engineers, the US Fish and Wildlife Service and US Geological Survey in an interim report about a three-year study underway that was funded by the Great Lakes Restoration Initiative.
The $6.15 million study found storm sewers carrying melted ice water from fish markets where carp are sold, fish eating birds leaving droppings behind, fish sampling gear and dead carcasses or slime on barges all can deliver Asian carp DNA to a waterway.
“The telemetry work was really interesting,” Baerwaldt said. “Anal swabs of tagged cormorants all came back positive. Yes, they recently had eaten Asian carp and moved over 800 miles. When we put that together with the poop study there was a direct line of evidence that cast a shadow of doubt on eDNA being correlated only with live fish.”
Those findings are significant, according to Kurt Schilling, the fisheries program manager for the USFWS Midwest office in Minneapolis MN. They illuminate various ways Asian carp eDNA can be moved from place to place.
“When eDNA emerged as a viable tool for detection and we started getting positives it was like now what does that mean,” Schilling said. “We got out with boats and gear and didn’t find any fish.
“The takeaway for me (from the study) is there are other vectors that produce a positive sample and that eDNA can stay for a number of days and there are a number of ways it can be moved around. Right now we can’t separate between live and dead fish, but some of the work this coming year will help.”
As the study goes forward the work effort will shift. The FWS will take over sampling and processing of the DNA samples at a new genetics laboratory in La Crosse , Wisconsin instead the Army Corps of Engineers lab in Mississippi.
The Army Corps will work to further calibrate the computer model being used to identify the DNA. The agency has requested another $1.3 million for the work.
Scientists will someday be able to determine the probability of DNA coming from a live Asian carp, according to Baerwaldt. Upcoming research will identify and catalogue how Asian carp DNA degrades with time and different types of exposure.
The current study began in an effort to answer questions that arose after the DNA was found, but large-scale efforts to find live carp came up empty-handed.
“We did a large-scale rotenone kill on six miles of water and fished the snot out places and still didn’t get any fish. We kept looking the (DNA) test results and didn’t have any good answers. That’s where this (eDNA) calibration study was born,” Baerwaldt said.
“We had been using eDNA since 2009 and were all excited about the new technology. Then we started applying it and started getting positives in weird places all over the place and decided that must mean something.”
Schilling said his agency will now take the lead on Asian Carp DNA sampling and processing.
“It’s a better fit,” said Schilling. “Our mission is to preserve protect and enhance fish and wildlife,” he said.
“One of the goals of GLRI is to have an early detection system in place. This is one of the first steps. We will be looking at tributaries around the Great Lakes. The Chicago Area Waterway will be priority one for us. The Great Lakes is the next priority and then come other hotspots like the Upper Mississippi and Ohio Rivers.
Baerwaldt said she doubts that any Asian carp got past the electric barrier on Chicago Area Waterway. And basin separation may prove more of a political question than scientific at this point.
“I hesitate to have anyone jump on one side or the other,” Baerwaldt said. “We are doing our due diligence and asking the right questions. We are fortunate to have funding when there isn’t a lot out there.”
Copyright © 2013 Howard Meyerson