Biologists discover Lake Erie silver
Plain Dealer Reporter
With the glee of treasure hunters searching
for sunken casks, U.S. and Canadian fishery biologists
exploring the Great Lakes say they've spotted a different
type of trove sparkling in the waters of Lake Erie.
Some even quip they've found "the
Pisces of ate."
What's got them buzzing is an all-but-extinct
native fish called the silver chub, which is reappearing
in Ohio in abundant numbers. It's an unexpected resurrection
for a ghost fish.
The return of the silver chubs after
their virtual absence of almost a half-century is good
news on two fronts for the lake.
The chubs are extremely sensitive to
pollution, so their presence indicates that Erie is continuing
to get cleaner. Moreover, these little fish, which aren't
eaten by humans, seem to have an unquenchable hunger for
zebra mussels, the exotic pests that have infested U.S.
Only one other species of North American
fish - the sheepshead - has successfully integrated zebra
mussels into its diet. So far, eating mussels have been
detrimental to all the rest, scientists say.
For example, Lake Michigan white fish
are in steep decline. Even when their stomachs are filled
with shells, their health fails because they can't get
any nutrition, said Tom Nalepa, a research biologist with
Lakes Environmental Research Laboratory
in Ann Arbor, Mich.
"Nature sometimes works in mysterious
ways," said Nicholas E. Mandrak, a research scientist
with the Canadian Department of Fisheries and Oceans.
"A nuisance moves into the neighborhood and the chubs
discover they have a taste for it, and now they're coming
back in huge numbers."
Mandrak, formerly on the faculty at Youngstown
State University, said silver chubs originally evolved
to eat small clams and native mussels.
They were all but gone from Lake Erie
by 1953, killed off by the industrial waste and other
toxic substances dumped into the lake up through the 1970s.
The pollution caused excessive growth of algae. When the
algae died and decayed, they used up all the oxygen near
the lake bottom, making it difficult for the chubs to
However, Mandrak doubts that the chubs
will ever to be able to eliminate the zebra mussels. "It's
not the solution. There will never be enough" chubs,
he said. "But if they can make a dent, that would
be pretty incredible."
The zebra mussel hitch-hiked from Europe
on freighters that unloaded ballast water in the Great
Lakes in the late 1980s. Since then, they have invaded
every major waterway east of the Mississippi River. Sewer
lines and water intakes are blocked by the mussels, which
also kill off native mussels.
The zebra mussels eat algae, filter plankton
and gobble up other micro food sources for fish. They
encrust rock ledges, reefs, shipwrecks and docks - and
grow virtually unchecked.
Although the food chain has suffered,
the mussels still have helped clear up lakes and streams,
Silver chubs also are a good source of
food for other lake fish.
Jeff Tyson, an Ohio Department of Natural
Resources wildlife expert, said the chubs are bottom feeders
with flesh "that's fatty, oily and packed with energy."
Among fish in the lake, he said, the chub probably are
preferred by pike and muskies.
"The silver chubs aren't exactly
overrunning the lake, but they are coming back strong,"