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Entries in invasive species (192)

Wednesday
Mar122014

Asian Carp Eggs Found in Upper Mississippi River

 

Just when we think that we know what is going on with Asian carp . . . 

The U.S. Geological Survey (USGS) says that researchers found eggs, including late-stage embryos, in samples collected last summer from the Upper Mississippi River, as far north as Lynxville, Wisc. 

Here's more from the USGS:

"This discovery means that Asian carp spawned much farther north in the Mississippi than previously recorded," said Leon Carl, USGS Midwest Regional Director. "The presence of eggs in the samples indicates that spawning occurred, but we do not know if eggs hatched and survived or whether future spawning events would result in live fish."

The Asian carp eggs and late-stage embryos were discovered two weeks ago while processing samples that were collected in mid-May and mid-June, 2013. The samples were taken as part of a larger research project designed to identify Asian carp spawning habitats. The eggs and late-stage embryos were 250 river miles upstream of previously known reproductive populations in the river. Spawning would have occurred upstream from this site.

Once the scientists visually identified the eggs, they examined other samples taken from the Mississippi River and found Asian carp eggs at seven locations between Pool 19 near Keokuk, Iowa, and Pool 9 of the main channel of the Upper Mississippi River near Lynxville. Iowa, Missouri, Illinois, Minnesota and Wisconsin border the navigation pools where these samples were collected.

The eggs and late-stage embryos were identified as bigheaded carps — either bighead carp or silver carp — through visual analyses of specific features of the eggs and embryos. It is also possible that some eggs could be from grass carp, although no eggs were visually identified as such. The USGS attempted genetic analyses to definitively determine which species of Asian carp the eggs belong to, but the results were inconclusive. Additional steps are being completed to attempt genetic confirmation, and those results are expected in one to two weeks.

The research project that collected these eggs is being coordinated by the USGS in collaboration with Western Illinois University. Scientists plan to collect additional samples from the Mississippi River in 2014 as part of their on-going research project.

"Invasive Asian carp could pose substantial environmental risks and economic impacts to the Upper Mississippi River if they become established," Carl said. "Further research will help us to better understand their habitat requirements and inform integrated control efforts."  

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.)

Tuesday
Feb182014

Exotics Take a Bite Out of Wetlands

Nutria photo from Louisiana Department of Wildlife and Fisheries website.

Most anglers know that Asian carp are harming this nation’s fisheries, from the Upper Midwest down to the Gulf Coast and eastward through the Ohio River watershed.

What many do not realize, however, is that other exotics also are doing severe damage. They don’t receive as much publicity because their range is more limited.

But in Louisiana, the nutria, a large rodent, is devouring the wetlands, destroying spawning and nursery habitat for a multitude of important sport fisheries. In fact, the state estimates that damage at any given time is about 46,000 acres, as about 5 million of the web-footed animals with large, orange teeth feed on the roots and stalks of aquatic plants.

Additionally, the giant apple snail also is taking a giant bite out of the wetlands. They’ve been banned from the state since 2012, but that was too late to keep them from becoming a destructive force, courtesy of irresponsible hobbyists who dumped their aquariums into waterways.

“They eat a ton of plant material, anything they can get their tiny little mouths on,” said Michael Massimi of the Barataria-Terrebonne National Estuary Program. “You are converting a water body from one dominated by plants to one dominated by algae.”

Asian carp, tiger prawns, water hyacinth, and giant salvinia also are among the exotic species doing damage to Louisiana’s coastal system.

Some limited good news is that the state’s nutria control plan, implemented in 2002, has lessened the impact of these furbearers, which were imported during the 1930s and promoted as a way to combat water hyacinth and other invasive plants during the 1940s.

Giant apple snails also are gobbling up wetlands.

Still the cumulative effect of these invaders is significant for an ecosystem already under siege. First came decades of habitat degradation and mismanagement, most of it originating from development and water diversions. These actions accelerated erosion and saltwater intrusion, which are crumbling away the equivalent of a football field every hour.

Then came the Deepwater Horizon oil spill and its aftermath, which added to the peril of an ecosystem that is critical for sustaining the food web of the Gulf of Mexico.

Fortunately, the spill also provided impetus for passage of the RESTORE Act, which provides a rare opportunity to restore and enhance the Delta and its wetlands. Guiding that restoration is a multi-state, multi-agency group known as the Gulf Coast Ecosystem Restoration Council.

And a coalition known as Vanishing Paradise is working to make sure that Council members remember the importance of habitat restoration, which can drive and support economic recovery.

“The people, business, communities, and economy of this region are undeniably reliant upon a healthy and productive Gulf, and ecosystem restoration should be the top priority,” said spokesman Ben Weber.

Sadly, passing legislation and creating coalitions will do little to counter the damage already being done by established exotic species, including the nutria and giant apple snail.

But something could be done to lessen the likelihood of future harmful invasions in Louisiana’s marshes and wetlands, as well as other waterways nationwide. Congress needs to strengthen the Lacey Act, which prohibits the import and trade of harmful species.

Here is how bad the problem is: Since the act’s implementation more than a century ago, only about 40 animal groups have been prohibited, and that usually occurred long after they were imported, escaped into the wild, and started doing damage.

By modernizing the Lacey Act, Congress could empower the U.S. Fish and Wildlife Service to first assess the potential risks associated with a species proposed for import before deciding whether to allow or prohibit its trade in the United States. The ineffectiveness of the current law is easily evidenced by Burmese pythons in the Everglades, Asian carp threatening the Great Lakes, and giant apple snails joining nutria in gobbling up Louisiana’s wetlands.

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.)