DNR Prepares for Potential Asian Carp Invasion | Environment
Written by the Michigan DNR
If – or when – Asian carp make their way into Great Lakes waters, will state fisheries management agencies be ready to deal with them? The Michigan Department of Natural Resources certainly intends to be - so much so, that its Fisheries Division recently staged a two-day exercise on the St. Joseph River to run though how it will react in the event silver or bighead carp show up there.
The agency chose the St. Joseph River for its run-through, as it is the first major waterway up the state’s Lake Michigan coastline from Chicago. Most fisheries biologists believe that Asian carp – which are already found in the Chicago Area Waterway System – are likely to enter the Great Lakes via Lake Michigan and, if they do, it’s a coin flip whether they turn left or right as they head up the lake.
Asian carp breed in rivers. It’s a safe bet that if they do hit Lake Michigan, they’ll wind up in the St. Joe.
"The St. Joe has optimal habitat for these fish to spawn and potentially establish a population," said Tom Goniea, the DNR fisheries biologist who oversees aquatic invasive species and designed the exercise. "These fish thrive in highly productive streams like the St. Joe."
The two-day event involved 27 fisheries technicians – all but two of the field techs in the state – and a handful of biologists. The DNR brought 14 boats – 12 for fisheries workers, one for conservation officers and a spare (which was pressed into duty). The crews roped off a 2-mile stretch of river several miles below the dam at Berrien Springs and strung nets across the river to prevent fish from heading up or downstream during the exercise.
The crews began the exercise by electro-fishing, collecting common carp, tagging them, and returning them to the water as part of a mark-and-recapture study to see how effective various techniques were at catching the fish.
The common carp were "surrogates for silver and bighead carp," Goniea said. "They’re roughly the same size and same body shape and you’re going to catch them in the same places of the river. That gives us a known quantity of fish in that closed section of the river."
After the fish had been tagged, the fisheries crews deployed stretches of large-mesh gillnet through the river.
"One of the techniques used to catch silver and bighead carp is to electro-fish and chase them into vertical walls of gillnet," Goniea explained. "Then on the second day, we’ll attempt to recapture those fish with no nets in place and we can compare how effective our techniques are at capturing the fish.
"Fisheries Division has never done anything like this on any of the state’s river systems."
The exercise took on the air of a military operation. Ed Pierce, a DNR fisheries technician supervisor out of Plainwell and a detail-oriented type, assumed command.
"There’s a lot going on here," Pierce said. "Lots of logistics – boats, meals, motel rooms, portable toilets, a dumpster. We even contacted the local food bank as a contingency in case we wind up catching salmon or steelhead in the nets."
The exercise went smoothly. The crews tagged a lot of fish and recovered many of them over the next two half-days. The first afternoon session included several thousand feet of gillnet set systematically so the most effective sets could be evaluated. The following morning, the electro-fishing crews went back at it without the accompanying gillnets.
As a result, biologists are formulating a strategy for what they’ll do if the real deal – live silver or bighead carp – shows up in a Michigan stream.
"Everything pretty much went according to plan," Goniea said. "The ideas we had for netting worked. The nets were deployable and stayed in place where we put them in the river. How effective they were, that analysis hasn’t been completed, but just the fact that they worked in that habitat was a significant positive.
"Upon further review, I believe this exercise will provide us with several options."
In addition to the common carp caught in the exercise, the crew captured a single grass carp, another invasive species that is on the prohibited list in Michigan, but has been found on rare occasions in the St. Joseph River.
"We knew they were in this river in extremely low numbers," Goniea said. "We’re pleased that our efforts resulted in the removal of one of these elusive fish."
Tammy Newcomb, the DNR’s senior water policy advisor and fisheries research biologist who coordinates the state’s Asian carp strategy, said the exercise was a necessary step in preparing for dealing with the invaders.
"We need to be prepared to make a prudent response if we get reports of bighead or silver carp in our waters," she said. "Those fish are so good at evading typical gear that we set up this experiment to see how we can best respond.
"Early on in an invasion is when we have the ability to contain and eradicate them and we will," Newcomb said. "We’re trying to demonstrate some leadership on this front."
For more information on Asian carp - including how to identify and report them; actions taken to prevent their spread; and frequently asked questions - visit the DNR website www.michigan.gov/asiancarp.