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Entries in Illinois River (13)

Thursday
May112017

Grass Carp Invasion Also Threatens Great Lakes Fisheries

 

While silver and bighead are the Asian carp of most concern these days for the Great Lakes, a third species has quietly been making inroads and is a growing worry for fisheries scientists in both the United States and Canada.

"For the first time, we have a binational, peer-reviewed study by some of the best minds and practitioners in the field who have a consensus on what the risk is to the Great Lakes from grass carp, and it's pretty substantial," said Marc Gaden of the Great Lakes Fishery Commission.

The vegetation eaters, which could decimate wetlands and aquatic grasses, have been found in Lakes Ontario, Erie, and Michigan. And, according to researchers, at least some of these invaders are reproducing.

"They've just been humming in the background," he added. "They haven't gotten a lot of attention. Once in a while one would get captured."

In fact, 23 have been caught in Canada since 2012, including five in Lake Ontario at Toronto, according to Becky Cudmore of Fisheries and Oceans Canada.

"Right now, the sterile fish outnumber the fertile fish. This isn't game over, but we are finding more of these fertile fish."

How did they get into the Great Lakes? Possibly through the manmade connection between the Illinois River and Lake Chicago, before electric barriers were erected. Introduced in the early 1960s to control invasive aquatic plants, they been around far longer than their more notorious cousins.

Likely too, some were introduced either intentionally or by accident. Unlike with silver and bighead, grass carp are easy to acquire and have been introduced illegally into both private and public waters by people who don't understand the consequences.

"Our assessment is saying that yes, they were showing up before, but now they're starting the invasion process," Cudmore said. "They have arrived. Now is the time to act."

Sunday
Dec202015

Noise Could Be Way to Slow Spread of Silver Carp

Anglers and other boaters already know that silver carp don't like noise, and arguably that's not a good thing. That's because huge schools of these exotic fish go airborne as they flee the sounds of outboard engines, often damaging boaters and injuring people.

But this aversion to noise also could provide a silver lining in the quest to slow the spread of silver carp, according to scientists with the University of Minnesota-Duluth (UMD) and the U.S. Geological Survey (USGS).    

“Our complex noise findings suggest that certain sounds could be used to divert silver carp away from strategic points on waterways or herd them into nets,” said Brooke Vetter, a UMD researcher and graduate student.

After placing speakers at the ends of outdoor concrete ponds, scientists tested carp response to pure sounds, which resemble a dial tone, and more complex noises. The fish quickly adjusted to the pure tones, never swimming away more than two consecutive times. But they continuously fled the more complex sounds.

Now researchers are testing complex noise as a way to control silver carp in the Illinois River.

“Silver carp threaten many waterways in the Great Lakes basin by competing with native species,” said USGS's Mark Gaikowski. “Understanding silver carp behavior is critical for determining effective techniques to minimize the ecological and economic damage of this invasive species."

Friday
Aug212015

Tennessee, Cumberland River Fisheries Threatened by Asian Carp

Most anglers know that Asian carp are overwhelming populations of native fish in portions of the Mississippi, Missouri, and Illinois Rivers. Likely they are aware that the invaders could have catastrophic consequences for the sport fishery if they migrate into the Great Lakes.

And almost certainly they have seen photos of silver carp leaping from the water, like the one above, as they are frightened by passing boats. This iconic shot was taken in 2007  by Nerissa McClelland of Illinois Department of Natural Resources from the chase boat as an electrofishing survey was conducted on the Illinois River, just upstream from Havana.

What most anglers do NOT know is that silver and bighead carp also threaten the Tennessee and Cumberland River systems , along with the world-class sport fisheries in their reservoirs. Most at risk right now are Kentucky and Barkley Lakes, but the invaders are moving steadily upriver from there.

In the October issue of B.A.S.S. Times, I'll have a detailed report on what's happening to these fisheries and what might be done to save them. Following is some insight regarding the problem from Ben Duncan , a commercial fisherman:

"I think it's too late to fully save the Mississippi and Ohio Rivers. The quantity of carp in both those rivers is unimaginable, although sustained fishing does help. If we don't start soon, the Tennessee and Cumberland Rivers will soon follow.

"Using the Cumberland River as an example, the numbers on the Barkley pool are large, while two pools up--- Old Hickory Lake --- catches, while becoming more frequent, are still at manageable levels.

" I have been on these lakes all my life, and spend more time on the water in a year than most people do in 10, and I can already see how native fish are changing their behaviors due to the invasion of carp. I think it's even influenced the crappie population and spawn on Kentucky Lake. Commercially, we catch way fewer fish in the bays than we did seven or eight years ago---  especially buffalo--- a fish that competes with Asians for food. Such large schools of carp decimate the food source so there's no reason to enter the bays. I have observed the same patterns in gizzard shad. 

"Currently, commercial harvest is the only defense. Kentucky and Barkley lakes are two of the most productive reservoirs in the country and it's concerning that Asian carp have made them so vulnerable. There are still several anglers unaware of the severity of the problem and most need to be educated on how tackling the problem is a collaborative effort among all stakeholders."

Sunday
Apr192015

Largemouth Bass Chow Down on Bighead Carp in Lab Tests

Bighead carp grow large. But bass eat them when they're smalll and more vulnerable

“Asian carp” actually refers to two species of exotic fish, not one. As they spread throughout the nation’s rivers, both pose threats to native fisheries.

As it turns out, though, there seems to be a big difference in their vulnerability to predation. That’s bad news for bighead carp, which grow larger, feed more exclusively on zooplankton, and are less abundant. And good news for the smaller silver carp, which have become infamous for endangering boaters with their leaping antics.

Researchers at the Illinois Natural History Museum and University of Illinois put small samples of both into experimental pools, along with bluegill, gizzard shad, and golden shiners. Largemouth bass in those pools ate more bighead carp than any other species, including silver carp. Scientists hypothesized that this may mean that young silver carp are more “street smart” than their bighead cousins.

While it’s good to know that bass can and likely do eat these invaders, especially bighead carp, whether this predation will help control them remains to be seen.

“Although new research is confirming that native fish can and do consume Asian carp, this not mean that all is well,” cautioned the Michigan State University Extension (MSUE). “In the LaGrange Reach of the Illinois River, at least seven native fish are preying on Asian carp. Even so, this reach has one of the highest densities of silver carp recorded anywhere in the world.

“Native plankton-eating fish like gizzard shad and bigmouth buffalo have declined and the long-term effects on gamefish are still uncertain.”

In 2008, biologists estimated more than 5,000 silver carp per mile in that nearly 80-mile stretch of the river, with a biomass of 705 metric tons.

“In the Great Lakes, we already know that native fish are adapting to non-prey items like quagga mussels and round gobies,” MSUE continued. “We also know that predation has not been enough to eliminate these species or prevent their negative effects. The same is likely true for Asian carp.”

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

Friday
Oct172014

Ground Zero for Asian Carp Invasion

Havana, Ill., is Ground Zero for the Asian carp invasion, according to the Illinois Department of Natural Resources. On the Illinois River, it’s about 200 miles south of Lake Michigan and 120 miles north of the Mississippi.

“You find more carp per acre, per mile of river, tan nearly anyplace else in the world,” says Kevin Irons, DNR’s Asian carp program director.

If you doubt that, check out this video.

Based on electrofishing surveys, bighead and silver carp now account for about 60 percent of the fish biomass in that stretch of the river. That means native species have declined dramatically because the exotics outcompete them for food and habitat.

And peaceful boat rides are a thing of the past because of silver carp, which go airborne when startled.

“People have been hit and seriously injured,” says DNR’s Matt O’Hara. “I know there have been some cases of broken noses and jaws.

“Pretty distressing when you come out here and you’re looking for native fish, and all you see is invasive Asian carp,” he adds.