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Entries in Great Lakes (109)

Friday
Mar212014

Stop Blaming the 'Villagers'

Today’s biology lesson is about the life cycle of zebra mussels. As an added bonus, I’m going to provide a little instruction in the lost art of journalism.

First, read this excerpt from an article about the exotic shellfish on the KAAL website in Minnesota:

 * * *

"Say you've pumped in 100 gallons of water off Lake Minnetonka and it comes in now and then pumps out, any villagers that happen to be in that tank can't get out either,” said Larry Meddock with the Water Sports Industry Association. The villagers are trapped. That's important because the filter reduces the risk of any hitchhikers being transported from one lake to another through ballast tanks on boats.

* * *

Now here’s the journalism lesson: Know what you’re talking about.

And here’s a clue to the biology lesson: “Villagers” don’t live in water; they live in a village. And they are people, not zebra mussels.

What, then, are the “villagers” that the KAAL author is referring to? Had she bothered to do any research, she would have discovered that the correct term is “veligers.”

Here’s what you need to know about zebra mussels and what that article failed miserably to explain:

Veligers are the microscopic, free-swimming larvae of zebra and other mussels. They can drift in the water for several weeks, before settling onto hard surfaces to grow into hard-shell adults.

They likely were introduced to the Great Lakes as veligers in the ballast water of ocean-going ships. They also are being spread within the United States in ballast, as well as in bilges, livewells and any other water left in a boats as they leave infected waterways.

As adults, they can hitchhike by attaching to boat hulls, props, and trailers, surviving out of water for a week or so.

That’s why it’s so important that you clean, drain, and dry your boat after leaving any water infected with zebra or quagga mussels. And the failure of many to take these precautions is a major reason that these problematic shellfish have spread out from the Great Lakes, and, in recent years even crossed the Continental Divide.

Aside from outcompeting native species for oxygen, food, and habitat, they clog water and hydropower plants, costing the nation’s economy more than $1 billion a year in damages and associated control costs annually.

Stop the spread of “veligers,” and leave the “villagers” alone.

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.)