Biologists target Great Lakes sea lampreys
Parasite responsible for decline of lake trout population
Published July 7th, 2004
SAULT STE. MARIE, Mich. (AP) — Federal biologists have
returned to the St. Mary's River to wage another round
of chemical warfare on the sea lamprey, a parasite blamed
for killing off most lake trout in the Great Lakes.
The U.S. Fish and Wildlife Service is targeting the river
connecting lakes Huron and Superior because it is the
region's primary breeding ground for sea lamprey. The
agency will apply lamprey-killing Bayluscide Granular
to a 110-hectare area through July 22.
The wildlife service has treated small streams throughout
the Great Lakes with a chemical called TFM. But it has
not been used in the St. Mary's River because of its relatively
high cost and because the river's water depths and currents
likely would render it ineffective.
Biologists had success in the late 1990s using helicopters
to apply Bayluscide Granular, which the wildlife service
says is non-toxic to humans, pets, livestock, mammals
and birds. Similar to a cold capsule, the granules have
a time-release coating that dissolves when they reach
the targeted area at the river bottom.
Since the sea lamprey invaded the Great Lakes in the
1950s, the lake trout population has dropped from 6.8
million kilograms caught annually in lakes Superior and
Huron to 135,000 kilograms. The U.S. and Canada spend
an estimated $15 million US ($19.9 million Cdn) a year
to control the parasitic eel.
The current batch of lampricide will be dumped from boats,
not helicopters. Applications will depend on weather conditions,
the Evening News of Sault Ste. Marie reported.
According to the wildlife service, each lamprey eel kills
20 or more kilograms of fish during its adult life by
attaching itself to the fish and sucking out its body
fluids. Lampreys prefer to feed on trout, salmon and whitefish,
but also have been known to feed heavily scaled fish like
carp and lake sturgeon, agency spokesman Terry Morse said.
Lamprey hatch from eggs and can live for several years
in silty river bottoms before travelling to the lakes
as adults. Great Lakes tributaries are treated every three
to five years with TFM, which is designed to kill the
Bayluscide granules and TFM aren't the only weapons in
the wildlife service's arsenal. Male lampreys have been
captured at various locations along the St. Mary's and
sterilized before being reintroduced to the river.
The various treatments have killed an estimated 90 per
cent of sea lamprey in the Great Lakes, according to the
U.S. Geological Survey.
"They're still out there," said Morse, "but
we have been very encouraged by what we have found."