|
 Ocean
Watch
Friday, May 07, 2004
Monster
Carp
While visiting my home town in
Wisconsin this week, I hiked along a breakwater to a lighthouse in nearby
Lake Michigan. There, the fresh breeze, choppy swell and endless view
reminded me of the ocean. This Great Lake smelled like the sea too, but
clearly this wasn’t salt air. It was fish air and I loved it.
The Great Lakes resemble the ocean in
some negative ways too. Both are threatened by various human activities
and both harbor what people consider bad fish. In Hawaii, the villains
are sharks and the introduced blue-striped snapper or taape. Here it’s
carps.
Although all four species of
introduced carps are a threat to the Great Lakes, the big hazard right now
is the bighead carp. These fish don’t have teeth and aren’t aggressive,
but they’re scaring people here, for good reason. Bighead carp have the
potential to wipe out nearly every living creature in the Great Lakes.
Bigheads aren’t your average carp.
These Asian imports grow to 110 pounds and can measure up to 50 inches in
length. To reach this enormous size, they eat half their weight in
plankton every day.
And that’s the problem. By gobbling
up most of the Lakes’ tiny plants and animals, bigheads hit the food chain
where it hurts the most: at the bottom.
A shortage of plankton squeezes out
the little fish that survive on it. And that’s it. With no small fish,
the trout, salmon and other fish-eaters in the lake are done for.
Anglers love fishing for trout and
salmon, and lots of people love the anglers. The Great Lakes sports
fishing industry generates an annual $5 billion to the region.
It was also economics that brought
bigheads here in the first place. Southern fish farmers imported these
carp in the 1970’s to clean algae from their ponds. The fish escaped
during floods about 10 years ago, and have been inching toward the Lakes
since then.
People are right to worry. No state
or federal laws exist prohibiting trade in, or release of, bighead carp.
And the carp are definitely coming. A 38-pound bighead was recently
caught in a Chicago lagoon only a few miles from Lake Michigan. Also, to
date, four bighead carp have been caught in Lake Erie, and a snorkeler
there spotted two more near a river entrance.
All the Great Lakes are connected.
Because the four bigheads taken from
Lake Erie were all adults, biologists don’t think the fish bred there.
But with no regulations on these rapidly reproducing fish, it’s just a
matter of time.
Today, it’s easy to buy bigheads in
both Canada and the U.S. One fish market in Illinois sells live bigheads
for $1.29 per pound. It’s up to the buyer to kill them.
Some softies, however, can’t do it.
They feel sorry for the gasping fish and set them free.
Alien species in the once-isolated
Great Lakes is an old problem, dating from the early 1800’s when the first
man-made ship canal to the Lakes opened. A century later, people reversed
the Chicago River’s flow, linking Lake Michigan to the Mississippi River.
Since then the largest freshwater
ecosystem on the world has been open to invasion from both sides.
People are currently working to
keep the carp out of the Great Lakes in the form of electric fences, new
legislation and public education.
There’s hope yet for the health of
the Midwest’s oceans.
|
|
