Botulism E Update from Canada

Date: 29 Dec 2007

National Post

The carcasses of hundreds of dead loons have washed up on the shoresof the Great Lakes in recent months, and necropsies on the birds donot explicitly say what is killing one of the country's nationalsymbols.

But the fat, healthy-looking birds have congested organs and half-digested fish in their stomachs, leading biologists to believe the loons succumbed to a spreading epidemic that has killed 75,000 birds, including 9000 loons, in the Great Lakes since 1999.

Diseased bird carcasses appeared this year [2007] for the 1st time on the beaches of Georgian Bay, a wildlife expert said. Last year[2006], the deaths were seen for the 1st time in Lake Michigan.

"Rather than sporadic outbreaks, which have occurred for years and years, now it is becoming much more generalized over the Great Lakes. It's becoming more widespread," said Kate Welch, a diagnostician withthe Canadian Cooperative Wildlife Health Centre, who performs necropsies on the birds. The loons, symbols of Canadian wilderness, died after eating badfish. More specifically, the loons died of type E botulism.

"The thought of botulism turning the Great Lakes into killing fields,it's not a good situation," Joe Kaplan, a biologist in Hancock,Michigan told the Muskegon Chronicle. The toxin produced paralyzesthe loons, Dr. Welch said; when they are no longer able to hold theirheads up, they drown."

"The loons, which are very emblematic for Canadians, are verylong-lived birds," Dr. Welch said. "They live up to 20 years or more,and if we're losing a substantial number of those birds in theirprime reproductive years, it may be 10 to 15 years before we see whatthat is going to do to the population as a whole."

Exact figures for the loon deaths are difficult to tally because the birds live almost entirely on water, and many of their bodies never wash ashore to be counted, she said. "There are probably huge numbersof mortalities that we just never see.

"There are about 545 000 loons that nest each summer in Canada, and while scientists do not believe they are in any immediate danger of being wiped out by type E botulism, the outbreaks could quickly reduce their numbers. Loons produce on average less than one chick per year.

No cases of human illness have been associated with the avian botulism outbreaks that have occurred on the Great Lakes. Humans only come in contact with type E botulism by eating infected fish or birds.

Over the years, people have been shaken by shores littered with dead loons, geese, ducks, gulls and cormorants. Horrified passersby at harbors or waterfront parks watched birds flailing around helplessly or struggling to keep their heads above water. Local media reported on the mysterious mass avian deaths.

The [disease] surfaced in the western end of Lake Erie in 1999 and quickly spread to lakes Huron and Ontario. The worst year was 2002,when 25,000 dead birds were counted in Lake Erie alone, according tothe Pennsylvania Sea Grant, a research program in Erie, Pennsylvania.

The deadly chain reaction started in the 1980s when zebra mussels and gobies, both invasive species, hitchhiked into the Great Lakes in the ballast tanks of ocean freighters from the Caspian Sea.

"It's a bit of a wake-up call that invasive species have long-term repercussions," Dr. Welch said. "They have substantially altered the ecosystem of the Great Lakes to the point where now we are seeing much more botulism."

Geoff Peach of the Lake Huron Centre for Coastal Conservation said that the United States and Canada need to enforce strict regulations governing ballast water management, or else other non-native species could find their way into our lakes.

Type E botulism results from a naturally occurring toxin, soconservation officials can do little to prevent the deaths. Butscientists are working on interrupting the food chain.

A team of researchers from the University of Windsor and the Ministryof Natural Resources are trying to create a tablet that will release sex pheromones to attract gobies and trap them.

Lynda Corkum, a University of Windsor ecologist who studies gobies, said gravid females swim toward the scent [that] scientists captured by leaving a male goby in a tank for several hours. While it is impossible to trap enough round gobies to reduce its population -- she estimates there are about 10 billion round gobies living in the western basin of Lake Erie -- the research could be used to stop gobies from spreading to inland rivers and lakes.
[Byline: Melissa Leong]