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Entries in Great Lakes (110)

Wednesday
Mar262014

Third Carp Species Also Threatens Great Lakes

Activist Angler caught this 30-pound-plus grass carp in a lake that has been damaged by illegal stocking of this exotic species. Photo by Robert Montgomery.

When people talk about Asian carp threatening the Great Lakes and its fisheries, they typically are referring to bighead and silver.

But a third species also potentially could damage this vast freshwater ecosystem if it becomes established in substantial numbers.

The grass carp was introduced into U.S. waters about 50 years ago, with the intent of using it to manage invasive aquatic vegetation. It has done its job--- and then some. Too often it has obliterated all vegetation in a water body, including beneficial native plants.

Additionally, it has escaped and established wild populations, as did the bighead and silver. Today the grass carp is believed to be in at least 45 states.

And now this invader poses danger for the Great Lakes.

Researchers recently documented that grass carp have spawned in the Great Lakes, specifically in Ohio’s Sandusky River, a tributary of Lake Erie. They also point out that 45 of them were caught in the Great Lakes between 2007-2012. That’s not a lot, but it’s 45 too many, especially since about half of those were capable of reproducing, meaning that an established population might already exist.

That does not bode well for bass, pike, and other inshore species that thrive in and around aquatic vegetation.

Read more here.

By the way, I have personal experience with grass carp. Years ago, ignorant property owners illegally stocked grass carp in the little lake behind my house because, they said, “they filter the water and improve the water quality.”  They did so, even though the lake contained little, if any, aquatic vegetation.

Somehow, the carp have survived and today some of them weigh 30 pounds or more. They’re the equivalent of big aquatic cows, degrading water quality, not improving it, as their wastes feed alga blooms during summer.

Also, hundreds of pounds of carp prevent growth of hundreds of pounds of bass, bluegill, and catfish. Like a farm field, a lake can sustain just so much biomass. 

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.