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Entries in USGS (9)

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."  

Friday
Dec272013

Snakehead is Carrier of LMBV

Scientists have confirmed the presence of Largemouth Bass Virus (LMBV) in northern snakeheads taken from two Potomac River tributaries.

That might seem a positive development for those who view the exotic predator as a threat to bass and other native fish. After all, LMBV killed thousands of bass during the late 1990s and early 2000s; now maybe it will do the same to snakeheads.

But that’s not a foregone conclusion. The virus doesn’t always turn into a deadly disease. As a result, researchers caution that snakeheads simply could be carriers for spreading LMBV to bass throughout the Chesapeake Bay watershed, especially since the two share similar habitats.

“The virus has been found in bass, sunfish, and other fish species, but largemouth bass is the only species known to develop disease from it,” reported the U.S. Geological Survey (USGS).

USGS and Virginia Department of Game and Inland Fisheries made the discovery while studying snakeheads for possible pathogens. Until now, little has been known about what diseases this introduced predator might carry and/or be susceptible to.

In 2011, though, researchers found bass with LMBV in all 16 bodies of water tested in Virginia, except the tidal James River.

“The long-term and population-level effects of Largemouth Bass Virus on bass inhabiting these rivers are unknown,” added Luke Iwanowicz, a USGS research biologist.

Meanwhile, efforts to control the spread of snakeheads have been unsuccessful, the USGS pointed out, with scientists predicting they likely will expand their range.

Monday
Dec232013

Prescription Drugs Contaminating Lake Michigan

Prescription drugs and other chemicals are contaminating Lake Michigan as far as two miles from the Milwaukee sewage discharges, according to researchers. That’s an unpleasant surprise for those who had theorized that water was diluting the pollutants to non-threatening levels.

With 14 chemicals found at levels of “medium or high ecological risk,” scientists don’t know what effect they are having on fish and other aquatic life. But they are concerned.

“You’re not going to see fish die-offs but subtle changes in how the fish eat and socialize that can have a big impact down the road,” said Dana Kolpin, a research hydrologist for the U.S. Geological Survey. “With behavior changes and endocrine disruption, reproduction and survival problems may not rear their ugly head for generations.”

The chemicals’ ability to travel and remain at relatively high concentrations means that aquatic life is exposed, so there could be “some serious near-shore impacts,” added Rebecca Klaper, an associate professor at the University of Wisconsin-Milwaukee and senior author of the study published in the journal Chemosphere.

Of the 27 chemicals found, the most prevalent were caffeine, metformin (an antidiabetic drug), sulfamethoxazole (antibiotic), and triclosan, an antibacterial and antifungal compound found in soaps and other consumer products. The latter is known to be toxic to algae and can act as a hormone disruptor in fish.

The real problem, though, is the witch’s brew created by the contaminants blending together in the fishery. “It’s going to be hard to ease out which of these compounds may do harm,” Kolpin said.

Klaper added that the Milwaukee Metropolitan Sewerage District does a better job than other plants at removing many compounds. But its facilities are just not equipped to handle the volume.

“For example, we found quite a bit of caffeine in the lake, and they’re removing about 90 percent of the caffeine that comes in for treatment. They can’t remove everything.”

Capturing these pollutants is a challenge not just for Milwaukee’s treatment plants but for those across the country, according to Kevin Shafer, executive director of the Milwaukee Metropolitan Sewerage District.

“At the time wastewater treatment plants were developed, these compounds were just not an issue,” he said.

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

Thursday
Dec192013

Brown Trout Can Interfere With Brook Trout Conservation

Photo of brook trout by Mark Sagan

No big news here: Brook trout populations throughout the East long have been damaged by stocking of non-native rainbow and brown trout. Brook trout have more specific habitat needs and they are less aggressive, both negatives in a world where species are moved about and ecosystems altered. And they are not trout, but char, related to Lake trout, bull trout, Dolly Varden, and Arctic char.

But this study by USGS does provide interesting insights into the brook trout/brown trout dilemma in New York.

Brown trout introductions could hamper the conservation of declining native brook trout populations, according to a new U.S. Geological Survey study.

Brook and brown trout are valuable sport fish that co-exist in many parts of the world due to stocking introductions. USGS researchers found that, in New York State, direct interactions between the two species, such as competition for food, have minor effects on diminishing brook trout populations compared to human-caused habitat disturbances. However, repeated, disproportionate stocking of brown trout in brook trout habitats could drastically decrease brook trout numbers.

"There is great potential for brown trout stocking to reduce native brook trout populations," said James McKenna, USGS scientist and lead author of the study. "But brown trout aren’t necessarily causing the current brook trout declines, and managers may be able to develop sustainable scenarios to support both fisheries."

The USGS study found that human-induced degradation (from dams and roads, among other causes) of the habitats of both species can affect the populations of either. However, because brook trout do better in forested watersheds, whereas brown trout can thrive in more agricultural environments, degraded watersheds and/or the elimination of forests may affect brook more than brown trout. Improper brown trout management could further threaten vulnerable brook trout populations.

Fisheries managers in New York use stocking to maintain brook trout—a native species—and/or brown trout—a non-native species stocked in New York for over 100 years—in some streams. Brook trout have been declining within its native range in recent decades, and there has been concern that the stocking of brown trout has caused these declines.

The report is published in the North American Journal of Fisheries Management and is available online.

For more information on USGS Great Lakes ecosystem research, please visit the USGS Great Lakes Science Center website.

Saturday
Jul202013

Asian Carp Infestation Worst in Mississippi, Missouri Basins

USGS bighead carp distribution map

Asian carp have been found in fisheries from Colorado to New Jersey and from North Dakota to Florida, according to a map released recently by the U.S. Army Corps of Engineers, the U.S. Geological Survey, and the Illinois Department of Natural Resources.

 “Asian Carp Distribution in North America” displays the presence of bighead and silver carp at all life stages, as well as black carp and grass carp occurrences. Since three bighead carp have been collected in the western basin over the years by commercial fishermen, Lake Erie is one of the green shaded areas, which indicates the presence of at least one adult fish. (This is not the map shown above. Go to link to see more detailed map.)

Not surprisingly, the most intense infestation is in the Mississippi and Missouri River watersheds, including the Illinois River, which connects to Lake Michigan via the Chicago Sanitary and Ship Canal.

On the positive side, no Asian carp have been found above the canal’s electric barriers during the past two years, despite hundreds of interagency monitoring trips, including 192 hours of electrofishing and 82 miles of netting.

But on the southeast side of the Mississippi River watershed, meanwhile, Asian carp are a growing problem for the Tennessee River and especially Kentucky Lake.

"Asian Carp by the thousands are flooding Kentucky Lake, causing a problem for fishermen, regular boaters and the other fish. With no natural predators the Asian carp are single-handedly eating the entire food supply, reports WBBJ.