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Entries in Great Lakes (108)

Monday
Mar172014

Another Troublesome Invasive Plant Is Spreading

A pilot project in Michigan has resulted in the discovery of an increased threat to fisheries posed by European frog-bit, an exotic floating plant.

Statewide monitoring by the Early Detection Rapid Response coalition revealed European frog-bit in Saginaw Bay, Munuscong Bay, and around Alpena on Lake Huron. Previously, it was thought to be established in just a few localized sites in the southeastern Lower Peninsula.

“Responding quickly to a new invasive species is critical to increasing our chances of success, and it requires a well organized, collaborative effort between multiple agencies and other partners,” said Russ Mason, chief of the Wildlife Division for the Department of Natural Resources (DNR).

Thanks to grant funding for the project through the federal Great Lakes Restoration Initiative, control measures were quickly implemented, including physical removal and trial treatments with herbicides. By mid September, 1,500 pounds of the invasive had been pulled out of the infected areas.

Additionally, education, outreach, and future control activities are being planned with angling groups and other stakeholders.

European frog-bit resembles a miniature lily pad, with leaves about the size of a quarter. Forming dense mats, it shades out beneficial submerged native plants, disrupts natural water flow, and inhibits access.

It originally was accidentally released into Canadian waters during the 1930s, spreading throughout Ontario and into New York, Vermont, and other eastern states.

(This article appeared originally in B.A.S.S. Times.)

Wednesday
Mar122014

Fish Pass Through Electric Barrier

The last line of defense against Asian carp entering Lake Michigan isn’t impenetrable, according to a new report by the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.

Fish can pass through the electric barrier unharmed when they get caught in the wakes of barges passing through. And that’s not all. Metal barges can deplete the charge, and small fish aren’t always susceptible.

"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength,” says an interim report based on laboratory and field experiments.

“Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."

The Corps emphasizes that the findings are preliminary, with more work to be done with the barge community and the Coast Guard to see how the barrier can be strengthened.

“There is no evidence that Asian Carp are bypassing the barriers; nor is there any indication Asian carp are in the vicinity of the barriers,” the agency says. “The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan.”

Critics point out that water samples taken near the barrier and in a canal on the lake side of the barrier have tested positive for the exotic fish. Plus, poisoning of the canal in 2009 revealed an Asian carp carcass.

Read more here.

(This article appeared originally in B.A.S.S. Times.)

Friday
Feb142014

Electric Barrier Is NOT Stopping Fish

Oh, yeah! That electric barrier is going to keep Asian carp from entering Lake Michigan via a manmade connection to the Mississippi River basin.

Or maybe not.

A video obtained by the Milwaukee Journal Sentinel shows small fish swimming through the electrified water, just 35 miles downstream from Chicago’s lakeshore.

And no one said that the invaders must be adult fish.

“The only thing holding back the Asian carp at the moment is the electric barrier, but few people beyond Illinois politicians, the canal-dependent barge industry, and the Army Corps are buying the idea that the barrier is doing its job. Many worry the agency's continued confidence in this leaky, last line of defense will take a tragic toll on the Great Lakes, the world's largest freshwater system,” said the newspaper.

Thursday
Feb062014

Invasive Species Threat Goes Both Ways

Mostly resource managers have been concerned about Asian carp invading the Great Lakes through a manmade connection with the Mississippi River basin. But exotics already in the lakes also could migrate out and spread into rivers throughout the Midwest, if the electric barrier separating the two systems is not 100 percent effective.

One of those is the Eurasian ruffe, a small perchlike fish that entered Lake Superior during the mid 1980s in the ballast water of European freighters. It then spread to Lakes Michigan and Huron, and, this past summer, researchers found ruffe DNA in Chicago’s Calumet Harbor.

“The Eurasian ruffe is a relatively small fish that produces a lot of eggs and reaches maturity very quickly,” said Lindsay Chadderton, Aquatic Invasive Species Director for The Nature Conservancy’s Great Lakes Project. “They feed from the bottom of the food chain, and they’re going to compete with native and introduced species dependent on the same fauna.”

On the positive side, Illinois officials emphasized that no live ruffe have been captured in the harbor. They said that the DNA could have come from a bait bucket or ballast tanks, not an actual fish.

Still, even the possibility that the ruffe could be poised to spread inland underscores how vulnerable both the lakes and the Mississippi River basin are to invasive species and the need for an effective two-way barrier, according to The Nature Conservancy and other conservation groups.

(This article appeared originally in B.A.S.S. Times.)

Wednesday
Feb052014

Asian Carp DNA Found in Lake Michigan

Lake Michigan now has joined Lake Erie as a fishery where Asian carp DNA has been discovered.

A single positive sample for silver carp was found in Sturgeon Bay this past summer, according to the Wisconsin Department of Natural Resources (DNR), which conducted the research along with the University of Notre Dame and The Nature Conservancy.

The water sample wasn’t screened for the presence of carp DNA until recently. It was collected originally in a search for evidence of Eurasian ruffe, another exotic fish species.

Is the finding cause for concern? That’s debatable. But it is reason enough to begin regular sampling of Sturgeon Bay.

“When we start talking about evidence for Asian carp in a system and the use of DNA, we talk about repeated sampling events and repeated detections,” said Chris Jerde, a Notre Dame scientist.

This latest discovery was from just one of 50 water samples taken in Sturgeon Bay and 282 total from the state’s portion of Lake Michigan.

But Jerde added that if Asian carp DNA were commonly spread by bird feces, boat hulls, and other means besides live fish, other positive samples would be noted from across the Great Lakes.

"We can talk about alternative pathways (for DNA to get into a water body), but we still have thousands of negative detections throughout the Great Lakes and we have one positive here."

DNR’s Bob Wakeman added, “It is what it is. We just need to clarify what it means.”

Despite the discovery of positive DNA in Lake Erie and even a couple of live carp over the years, no evidence has been found of a breeding population.