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Entries in silver carp (28)

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.

Friday
Mar282014

Mapping the Invasion

This screen shot shows zebra and quagga mussel invasion as of 2006.

Nature Conservancy has produced some great interactive maps showing how invasive aquatic species have spread out across the country from their point of introduction.

Featured species include bighead and silver carp, zebra and quagga mussels, Eurasian ruffe, round goby, sea lamprey, and black carp.

Also, in late 2012, the organization released a report saying that aquatic invasive species “cost businesses and consumer in the Great Lakes region hundreds of millions of dollars annually in direct costs and even more from indirect costs related to removal, maintenance, and management of those species.

“Meanwhile, state and federal governments are currently forced to spend additional millions as they attempt to control the impacts and prevent the spread of AIS (aquatic invasive species).”

According to the report, the largest industry affected by AIS in the Great Lakes is tourism and recreation, which is responsible for employing more than 90,000 people in the region, generating $30.3 billion annually in revenue. Costs range from monitoring and controlling AIS to lost revenue from beach closings affecting hotels, restaurants and other tourism-related businesses.

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."  

Tuesday
Nov262013

Carp Threat Moves East

This Asian carp was caught at Kentucky Lake, Photo by Steve McCadams.

Asian silver carp DNA has been found as far up the Ohio River as Wheeling, West Va., and Pittsburgh, Pa. That’s bad news for East Coast river fisheries.

The silver is most noted for leaping from the water when frightened, injuring passing anglers and other boaters. But the most damage is being done to our waterways, as silver and bighead carp crowd out and outcompete native species for food and habitat.

"Unfortunately, the test results provide some evidence that this invasive species could be in the upper Ohio River in Pennsylvania," John Arway, executive director of the Pennsylvania and Boat Commission.

 "This is an early warning sign, since we don't know for certain the origin of the genetic material. We don't know if the eDNA came from live or dead fish or if it was transported from other sources, like bilge water or storm sewers, or even waterfowl visiting the basin."

For years, most of the focus was on the fear that Asian carp would devastate fisheries in the Great Lakes when/if they gain entrance. But now they also are threatening the inland waters of Iowa, South Dakota, and Minnesota, as well as the Cumberland and Tennessee rivers and their reservoirs, including Kentucky and Barkley lakes.

Read more here.