JUDY WOODRUFF: For those stations not taking a pledge break, we have a report on the threat posed to waterways from the Eastern Crayfish.
Tonight's story comes from Vince Patton of "Oregon Field Guide," a production by Oregon Public Broadcast.
VINCE PATTON: As discoveries go, this one seemed anti-climatic.
JEFF ADAMS: We've got all sizes of them here, too.
VINCE PATTON: Five years ago, Jeff Adams came to this spot near the town of John Day and found some crayfish as easily as he trapped more today.
JEFF ADAMS: There were hundreds and hundreds of crayfish at one of the sites that we looked at. Just the sheer numbers seemed very odd and out of place.
VINCE PATTON: Other scientists checked his samples and realized these crayfish belong a couple thousand miles away.
JEFF ADAMS: Certainly, it was a shock to see it up here. It's a well-known species to cause a lot of ecological damage in the Upper Midwest and it's never been found west of The Rockies, west of the Continental Divide. And that's a big concern, when you see something hop a continental divide and invade a new -- a new region.
VINCE PATTON: From Jeff's first spotting in 2005, Rusty crayfish have sprinted downstream. They have now colonized 30 miles of the John Day River.
Professor Julian Olden of the University of Washington has been studying invasive species in the John Day River for several years.
JULIAN OLDEN, University of Washington: They're pretty thick through here. So it's like a couple of kicks. There's pretty much a crayfish under every rock. That's the reality of it.
It's a great catch. There's at least a dozen there.
The species are native to the Upper Ohio River drainage and the Midwestern U.S. but now have been introduced to about 18 states and two Canadian provinces, ranging from Ontario and Quebec all the way down to Tennessee.
VINCE PATTON: Oregon's native Signal crayfish can appear either bright red or drab green.
JULIAN OLDEN: The Signal crayfish has a beautiful brown olive color. It has some nice white spots right on its claw. It's a quite beautiful, nice and smooth crayfish.
VINCE PATTON: Rusty crayfish may be green, too, but they carry a trademark rust spot on their side. When aquatic invasives move around the country, there's a standard list of usual suspects -- anglers and their boats often give them unintentional rides. But not this time.
JULIAN OLDEN: Here in the West, there seems to be kind of a unique pathway that hasn't really obtained that much attention. We see a quite different story here. Crayfish are using the classroom.
You know, they're -- they're using the classroom for a reason. They -- I think they illustrate biological life quite well.
KELTON: Well, we have the Rusty crayfish in the tank right here.
I think they're pretty cool. Yes.
VINCE PATTON: Crayfish are sturdy. They can survive a lot of handling. That makes them good for fourth and fifth graders, who are learning about biology, ecosystems and life cycles.
JENNIFER ENGLAND, teacher: You can talk about it, you can look at a -- a movie, but it's not the same as actually picking it up and learning how to -- to hold a crayfish and what are the structures and how really unique are they?
GREGORY: Right here, this is where the eggs would be if this was a female, but it's a male.
CHILD: Don't be scared.
DR. SAM CHAN, Oregon state university: The Rusty crayfish is one of several crayfish that are shipped around the country to, roughly, probably 25 percent of elementary classrooms throughout the United States. And usually they ship between a dozen to two dozen in each classroom.
VINCE PATTON: The problem comes when the school year ends.
What should they do with their living specimens?
SAM CHAN: Often, it's done very innocently. Most people feel that the best thing to do is to return plants and animals to nature, where they came from.
This is Dixon Creek. This is the main creek in Corvallis. And it's also a creek where at least flows through the backyards of four different elementary schools.
VINCE PATTON: Dixon Creek now has invasive crayfish.
Dr. Sam Chan of Oregon State says the schools that back up to the creek are very likely the source. Every time a Red Swamp crayfish from Louisiana or a Rusty crayfish from the Upper Midwest comes head to head with Oregon's native Signal crayfish, the Signal loses.
At Franklin School in Corvallis, Jennifer England has been teaching with live animals for 15 years.
JENNIFER ENGLAND: Skim and see if you can find something about how to care for them.
VINCE PATTON: It was only three years ago she learned that supply companies were shipping her an invasive species.
CHILD: He's made at you, Conan.
VINCE PATTON: Fortunately, she had never dumped live animals in streams.
CHILD: They would use their back tale and they would flop it back and forth.
VINCE PATTON: Experts at Oregon State suggested this could make a good lesson for her kids.
JENNIFER ENGLAND: It blossomed. It grew immensely and became quite a good project.
GREGORY: They will eat the fish eggs that are in the rivers and they will also kick the native crayfish out of their habitats.
SAM CHAN: Their students are learning about invasive species while learning about science.
VINCE PATTON: After caring for their crayfish for months, the children often aren't wild about killing them. But they're learning that may be the only responsible option.
CHILD: I don't think he likes the (INAUDIBLE) exhale.
GINGER: Sometimes we just wait until they just die of old age.
GREGORY: We actually put them in a bag and put them in the freezer.
And so that was a very painless way for them to go. We didn't have to put them out into the ecosystem that we have over here.
VINCE PATTON: Wildlife officials say it's against state and federal law to ship these crayfish into Oregon or Washington. Oregon wildlife officials sent warning letters a couple of years ago to the major supply companies. The shipments have continued.
But officials have not chosen to aggressively enforce the law.
A couple of years ago, even Professor Olden discovered how easy it was to obtain an illegal shipment of invasive crayfish.
JULIAN OLDEN: I mean and that was probably the most shocking moment. A box full of non-native crayfish that we just got, you know, delivered right to our door.
VINCE PATTON: He traced crayfish shipments to schools near the John Day River, too. Now, this river has at least 30 miles of invasive crayfish. Only distance and time stand between here and the Columbia River.
JULIAN OLDEN: There's no way of containing crayfish in large river systems like this.
VINCE PATTON: Five years ago, on this stretch of river, Jeff Adams found only one Rusty crayfish.
JEFF ADAMS: Yesterday, when I got back here for the first time in five years, the second my foot hit the water, I probably saw 30 or 40 scatter away. So it's a pretty -- a pretty dramatic difference.
VINCE PATTON: Since crayfish shipments continue to classrooms, Northwest scientists will focus their efforts on teaching the teachers and their children.
JIM LEHRER: You can see an extended version of that story by following -- excuse me -- by following a link on our website.