An outbreak of botulism in the eastern basin of Lake Erie, which has killed hundreds of thousands of fish and thousands of birds, among other wildlife, has grown so pervasive as to include even fly larvae on lakeshore beaches.
It is not yet clear whether the disease, identified as a type E botulism, will spread lakewide or spill into Lake Ontario.
“We're still in the problem-describing stage, but we're making headway,” said Ward Stone, wildlife pathologist for the New York Department of Environmental Conservation. “It seems to be able to kill one heck of a lot of things.”
Stone noted that evidence of botulism kills has been found in both New York and Pennsylvania waters, and likely also is affecting the corresponding Ontario side.
Last fall some 6,500 water birds, including about 1,000 prized common loons and more mergansers, were killed by a botulism outbreak in the basin.
Since then, fish kills have littered the east end of the lake. Don Einhouse, an NYDEC biologist at the state's Lake Erie Fisheries Research Station at Dunkirk, said that close to 90 percent have been sheepshead.
But the kills also have included smallmouth bass, some of them trophy size, and about 20 rare Great Lakes Sturgeon, some of them more than seven feet long. “It's a tremendous loss,” said David Davies, a biologist at Ohio's fisheries research station at Sandusky, about the sturgeon.
Other species in the toll include some walleye, rock bass, and stone cats. Stone said that the fish toll may be in the millions “if you include the little fish.”
In addition, bottom-dwelling, salamander-like mud puppies have died, as have several or more bird species. The bird toll includes mergansers, black-backed gulls, herring gulls, ring-billed gulls, double-crested cormorants, and sanderlings, the latter a shorebird. Many of the birds are thought to have fed on dead , infected fish carcasses.
An NYDEC technician has beenwalking beaches to collect carcasses. Stone thinks that turtles also may be affected, though no specimens have been found.
Both dead and dying sheepshead were infected with the botulism, which leads Einhouse to conclude the outbreak has spread by ingesting food. Most of the dead fish are bottom feeders; the sheepshead were full of round gobies.
Gobies are an invader pest, dumped in the Great Lakes from ballast-water from overseas ships. Their numbers have exploded in Lake Erie, as have those of one of their primary foods, zebra mussels. The mussels are another, earlier overseas alien pest.
“Just about all these fish had gobies in them,” said Einhouse.
Concerns also have arisen that migrating waterfowl and other migrant birds this fall may feed into the infected food-chain.
Einhouse noted that the bacteria that cause type E botulism are found almost everywhere. But it takes a special set of circumstances to allow for formation of the type E toxin that actually does the fatal poisoning. Researchers still are working on understanding the mechanism.
Stone said it is premature to jump to conclusions that gobies and zebra mussels - and their larger cousins, quagga mussels - are solely to blame.
“It's more complex than that.” The problem, the pathologist said. He theorized that the botulism involved may be a new strain of type E from overseas, dumped with ballast water on the same pathway as the mussel and goby infestations.
He noted that type E outbreaks have been recorded in the upper Great Lakes as far back as the mid 1960s, but were not seen in New York waters until last year.
Even insect larvae and midge larvae, which are fed on by small fish, show signs of the botulism bacterium. The outbreak also has extended to fly larvae found on the beaches, Stone said.
“We've still got a long way to go. ... This is an international problem,” he stated, calling for lakewide agency meetings.
Just such a meeting is set for Thursday at Dunkirk, where the Lake Erie Committee of the Great Lakes Fishery Commission is gathering.
Roger Knight, supervisor of the Ohio station at Sandusky, said the botulism dilemma is on the agenda and that the committee is “very much aware of it.
“It's at the forefront of Great Lakes issues. Everybody is trying to get a handle on this.”
“We've not seen any evidence of this (outbreak) in the western basin of the lake, including in Michigan or western Ontario waters. But we're looking. We will definitely collect specimens if we are aware of them.”
The researcher said that biologists have to be careful investigating fisheries kills, inasmuch as there are many other natural causes and explanations for mortality. However, mass kills readily would be suspect.
Until the cause is isolated, a cure cannot be attempted, Knight noted. “It's a mess.”
The eastern basin dieoffs have slowed somewhat in recent weeks, said Bill Culligan supervisor at the Dunkirk station. “It was at its worst in August.”
The NYDEC has alerted the public to be careful about handling dead fish and other wildlife, especially on the beaches and shoreline. Pets also should be kept from scavenging on dead fish or wildlife.
A fresh-caught fish, properly cleaned and cooked, should be safe. Thorough cooking should destroy any toxin present.
Culligan said that cases dating to the 1960s indicate that most human infections have come from eating raw fish or improperly smoked fish. He warned against using cold-smoking methods and to keep temperatures high when smoking fish for the table.
Steve Pollick is The Blade's outdoor writer. E-mail him at firstname.lastname@example.org.