Published Date: 2008-01-03 23:00:19
Subject: PRO/AH/EDR> Botulism, avian - Canada: Great Lakes
Archive Number: 20080103.0031
BOTULISM, AVIAN - CANADA: (GREAT LAKES)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 29 Dec 2007
Source: National Post [edited]
The carcasses of hundreds of dead loons have washed up on the shores
of the Great Lakes in recent months, and necropsies on the birds do
not explicitly say what is killing one of the country's national
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  for the 1st time on
the beaches of Georgian Bay, a wildlife expert said. Last year
, 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 with
the Canadian Cooperative Wildlife Health Centre, who performs
necropsies on the birds.
The loons, symbols of Canadian wilderness, died after eating bad
fish. 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 paralyzes
the loons, Dr. Welch said; when they are no longer able to hold their
heads up, they drown.
"The loons, which are very emblematic for Canadians, are very
long-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 their
prime reproductive years, it may be 10 to 15 years before we see what
that 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 numbers
of 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
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 to
the 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, so
conservation officials can do little to prevent the deaths. But
scientists are working on interrupting the food chain.
A team of researchers from the University of Windsor and the Ministry
of 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]
[Map of Great Lakes:
Image of Common Loon _Gavia immer_):
Image of invasive round gobie (_Neogobius melanostomus_) held in
gloved hand to give scale:
[There is a good deal of relevant information regarding these deaths
in ProMED-mail post 20071207.3942. I would encourage the reader to
review this posting as I will not repeat the information here.
The greatest advance this article gives us insight into is the
research being done on the gobies. This is significant news. I
suspect that Lynda Corkum is correct in that it will never eliminate
the gobies, but it may prevent their spread.
The gobies and zebra mussels are excellent examples of the ease with
which invading species can hitch a ride from other parts of the
world. - Mod.TG]