DNA from silver
carp was detected in one of 200 water samples taken in July from the river
in Allegan County, this one from below the Caulkins Dam about 24 miles
from Lake Michigan, the state Department of Natural Resources and the U.S.
Fish and Wildlife Service said.
The discovery
marks the first time so-called environmental DNA for silver carp has been
found in Michigan's Great Lakes waters outside of Maumee Bay in Lake Erie.
The term "environmental DNA" refers to genetic markers that fish leave
behind as they move through waters, shedding scales, mucous or excrement.
Scientists have
been testing waters for Asian carp DNA in an effort to track their
progress toward the Great Lakes. Bighead and silver carp were imported to
the Deep South from Asia in the early 1970s and escaped into the
Mississippi River, where they have been migrating northward since. They
have invaded numerous tributaries including the Illinois River, which
leads to Lake Michigan, although authorities have installed electric
barriers near Chicago in hopes of stopping their advance. The large,
voracious fish compete with native species for food.
The discovery of
genetic markers doesn't necessarily prove the presence of live carp, as
scientists say it could come from other sources, such as fishing gear or
bird droppings that came in contact with the DNA. But some contend the
presence of live fish is the likeliest explanation.
"While we don't
have evidence of a live fish in the water, we treat this finding very
seriously," Michigan DNR senior water policy adviser Tammy Newcombe said.
The agency has
requested assistance from the Fish and Wildlife Service for additional
surveillance on the lower Kalamazoo River, and authorities planned to
begin collecting an additional 200 samples Tuesday. Results should be
available within a month.
Also, the DNR
will boost presence of its staff along the river, which is popular for
recreational activities such as fishing and boating, to ask anglers to
report any Asian carp sightings. The agency plans to place information in
local bait shops to heighten public awareness.
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Posted 10/7/2014