Undercurrents: beneath the obvious

December 17, 2007

Zebra Muscles cost a billion bucks

Filed under: Great Lakes Issues,Great Lakes Threats,Invasive Species — nemo @ 10:07 pm

The Columbian (Clark County, Washington) summarizes the efforts and costs associated with zebra muscle clean-up:

The non-native bivalve has proliferated in the Great Lakes and Mississippi River, costing more than $1 billion to remove from clogged irrigation pipes. Scientists believe the filter-feeder has fundamentally altered the environment by devouring zooplankton that forms the bottom of the food chain.

Researchers noted that the rate of zebra mussel expansion in the Midwest has slowed considerably since the mid-1990s. While boat-inspection programs and public education may be playing a role, the scientists at Oregon State hypothesized there might be something else to it.

So they examined calcium levels in the water.

“That’s what they make their shells out of,” said Thom Whittier, a faculty research assistant at Oregon State who wrote the study with three other researchers.

Tabulating water-sampling data from 3,000 river sites across the country, the OSU scientists drew up the first broad-scale map documenting the relative risk of zebra mussel infestation nationwide. They concluded that relatively high calcium concentrations in the water correlated strongly with the presence of the Asian freshwater mussels, while rivers with relatively low concentrations had a low risk of infestation.


May 21, 2007

DNR (MI) unsure on extent of fish virus’ damage

Filed under: Great Lakes Threats,Invasive Species,Michigan — nemo @ 12:41 pm

The Sheboygan Press reports on the progress of VHS:

Lake Michigan is likely infected with viral hemorrhagic septicemia, which is killing one fish species in Little Lake Butte des Morts near Oshkosh, and officials are taking a wait and see attitude about how destructive it’ll be.

“We are virtually certain that it is in Lake Michigan,” said Randy Schumacher, [Michigan] state Department of Natural Resources Southeast Regional Fisheries supervisor. “It is probably in Lake Winnebago as well.”

Technorati Tags: ,

February 2, 2007

VHS in the Great Lakes longer than originally thought

Back at this post, VHS was thought to be in Lake St. Clair, Lake Erie, the Niagara River, Lake Ontario and the St. Lawrence River. That thought may now be changing.

Fish disease may be in Lake Michigan already:

Just two and half months ago … experts said VHS had yet to work its way into Lake Huron. They predicted it might be two to four years away from Lake Michigan waters. At that time it was a problem in lakes Ontario, Erie and St. Clair, along with the St. Clair and Detroit rivers.

But now we find out that just isn’t so. At least not quite. Two to four years may be accurate, but the starting point has shifted.

DNR officials say the clock reset once old, frozen fish samples were rechecked. They did this last year.

“What we found is that VHS was present in Lake St. Clair in 2003 and in Lake Huron in 2005,” Kelly Smith, the DNR fisheries chief, said. “Go two to four years out and you are at 2007 for Lake Michigan.

“I’m guessing that it’s already there.”

Technorati Tags: ,

January 25, 2007

Fish-killing virus (VHS) confirmed in Lake Huron

Filed under: Great Lakes News,Invasive Species,Michigan — nemo @ 8:32 pm

Bad news for Lake Huron:

The Michigan Department of Natural Resources said it confirmed the presence of viral hemorrhagic septicema, or VHS, in fish taken from Thunder Bay and from waters off Rogers City and Cheboygan.

Previously, VHS had been found only in two of the Great Lakes — Ontario and Erie — and in Lake St. Clair. But officials have predicted the virus eventually would spread across the entire lake system.

For those not familiar with Michigan, Thunder Bay and Rogers City are quite north and within an hours drive of the Straits of Mackinaw and Lake Michigan.

Technorati Tags: ,

January 22, 2007

Bills introduced to create a Great Lakes Asian Carp barrier

Filed under: Great Lakes News,Illinois,Invasive Species — nemo @ 1:28 pm

The Green Bay Press-Gazette reports on new efforts to prevent Asian Carp from entering Lake Michigan.

Two Illinois Congress members introduced legislation to fund an electric barrier keeping the nonnative Asian carp from entering the Great Lakes. Biologists believe the carp would cause havoc for boaters and anglers, and threaten the region’s $4.5 billion fishery.

Rep. Judy Biggert, R-Ill., and Sen. Richard Durbin, D-Ill., introduced the Great Lakes Asian Carp Barrier Act (HR553 and S336), which would provide approximately $9 million to construct and maintain a permanent electric barrier.

The project has struggled to find funding in recent years.

Technorati Tags: ,

January 10, 2007

5 Things to Know About Viral Hemorrhagic Septicemia (VHS)

Viral Hemorrhagic Septicemia at a glance:

What is it?

Viral Hemorrhagic Septicemia (VHS) is a fish disease that may cause bulging eyes, bloated abdomens, inactive or overactive behavior and hemorrhaging in the eyes, skin, gills, and at the base of the fins. It also attacks the internal organs of fish, leaving them bloody looking. Fish mortality is highest in low water temperatures between 37-54 degrees Fahrenheit.

The virus poses no threat to humans.

What species are affected?

VHS has been found in 37 species, including muskellunge, smallmouth bass, northern pike, freshwater drum (sheephead), gizzard shad, yellow perch, black crappie, bluegill, rock bass, white bass, redhorse sucker, bluntnose sucker, round goby and walleye. It has not been confirmed in salmonids in the Great Lakes, but has been known to infect those species.

Where is VHS found?

VHS was observed as early as 2005 in freshwater drum in Lake Ontario and in muskellunge in Lake St. Clair. In 2006, VHS was blamed for fish die-offs in muskellunge in Lake St. Clair, freshwater drum and yellow perch in Lake Erie, and round gobies in Lake Ontario.

As of January 2007, waters known to be infected with the virus include Lake St. Clair, Lake Erie, the Niagara River, Lake Ontario and the St. Lawrence River. Or maybe more — see update here: VHS in the Great Lakes longer than originally thought

How is VHS spread?

Fisheries managers don’t know for sure how VHS has spread. They’re guessing the virus moved to the Great Lakes from the Maritime Provinces via ballast water from ocean-going ships in 2002. Biologists believe the virus can move between fish populations, making them worry all of the Great Lakes could eventually have a VHS presence.

If the virus can spread by infected fish, it could be seen in Lake Huron and Lake Michigan in two to four years.

What can be done to stop VHS?

In the short term, boaters and anglers can disinfect their equipment with a bleach cleaning solution. Managers are urging anglers not to move fish from known infected waters to uninfected waters. They also ask anglers to leave all bait and livewell water in the lake from which it was taken.

Source: Ludington Daily News

Technorati Tags: ,

January 8, 2007

Ontario limits use of live bait fish to curb spread of fish virus

Filed under: Canada,Great Lakes News,Invasive Species — nemo @ 8:38 pm

From mlive.com comes this news item on steps Ontario is taking to prevent the spread of viral hemorrhagic septicemia:

Ontario is putting restrictions on live bait fish in an effort to stop a new fish virus from spreading to central and northern areas of the province.

Viral hemorrhagic septicemia has been discovered in fish from the lower Great Lakes. The disease isn’t a threat to human health, but it has been linked to the die-offs of at least four species of fish.

Waters known to be infected with the virus include Lake St. Clair, Lake Erie, the Niagara River, Lake Ontario and the St. Lawrence River.

Technorati Tags: ,

December 22, 2006

European invader (shrimp) found in the Muskegon Lake Channel

Filed under: Ballast,Great Lakes News,Invasive Species,Michigan — nemo @ 2:37 pm

The Muskegon Chronicle reports on the latest invasive species to be spotted:

A species of shrimp previously found only in the seas of eastern Europe has now been discovered half a world away — in the Muskegon Lake Channel.

Thousands of bloody red mysid, Hemimysis anomala, were discovered in the channel in November. It is the most recent addition to a list of Great Lakes invader species that now numbers more than 180.

Researchers at the National Oceanic and Atmospheric Administration’s Lake Michigan Field Station who found swarms of bloody red mysid said the half-inch-long shrimp were likely imported to the Great Lakes in the ballast water of an oceangoing freighter.

Scientists said the discovery was unsettling for two reasons: It again demonstrated that exotic species are still entering the Great Lakes; and the imported shrimp may compete with fish for zooplankton, a microscopic source of food.

Technorati Tags: ,

Next Page »

Blog at WordPress.com.