The Big Story Blog

Silver carp knocking at the door

Posted at 6:20 AM on October 21, 2011 by Paul Tosto
Filed under: Environment

silvercarpphoto.png
(Department of Fisheries and Allied Aquacultures, Auburn University)

Yes, this is the carp that jumps out of the water and hits you in the head. Yes, it has the potential to wreak havoc on Minnesota fisheries. And, yes, it's here.

News came Thursday that water sampling found DNA evidence the silver carp have made it up the Mississippi into the the Twin Cities, near the Ford Dam in St. Paul.

Today, we'll take a deep dive into the issues surrounding the carp. We'll also look into other invasive species threats and what's happened. It may sound like a dumb question, but are invasive species always bad?

Post below if you have some experience with the silver carp or other invasive species. Tell us what happened and we'll all get a little smarter.

Here are some of the things we know this morning.

1.) It was inevitable. We knew the silver carp was coming. A Minnesota DNR report in 2007 acknowledged, "Preventing the introduction of Asian Carp into Minnesota waters is a daunting challenge and unlikely to be successful over the long-term."

A year after that report, a silver carp was caught near La Crosse, Wis.

A U.S. Geological Survey map also makes it pretty obvious it was going to be tough to keep out the carp.

carpmap.png

2.) It will get political. We haven't seen a carp body yet. But MPR News reporter Tim Nelson captures the potential problems when it happens.

Actually finding the fish could touch off a legal and political battle. The Ford Dam has a unique construction that would make it one of the only existing barriers to the fish on the Mississippi. But that would require closing its locks to shipping -- forever.

The risk is that fish could potentially spread like other invasive species and damage the state's $1.6 billion sport fishing industry.

But shipping is also a multi-million dollar industry that depends in part on the Mississippi River in the Twin Cities.

3.) They are destructive. Here's how the U.S. Fish & Wildlife Service at La Cross describes the eating habits of the silver carp:

This fish is a very proficient feeder which uses gill rakers that are fused into sponge-like porous plates. The silver carp can consume two or three times their weight in plankton each day.

Because of its method of feeding, the silver carp is in direct competition with all native fish larvae and juveniles, adult paddlefish, bigmouth buffalo, gizzard shad, and native mussels.

That's a fish that has no intention of leaving without a fight.


About Paul Tosto

Paul Tosto

Paul Tosto writes the Big Story Blog for MPR News. He joined the newsroom in 2008 after more than 20 years reporting on education, politics and the economy for news wires and newspapers across the country.