UNIVERSITY PARK, Pa. -- The bright yellow signs will go up this spring at boat launches along the Ohio River, at local fishing tackle shops and anywhere else folks who enjoy the river gather. "Have You Seen This Fish?" they ask in bold letters, just above the picture of a ridiculous-looking finned creature with a long snout, an undershot mouth and a beady eye.

"This fish can grow as large as 7 feet long and weigh up to 100 pounds," the sign says. "If you happen to catch one of these rare fish, please return it to the water as soon as possible. We would like to know where, when and how you caught this fish."

They have got to be kidding -- gargantuan cartoon fish in Pennsylvania?

But they aren't kidding. For Penn State researcher Patrick Barry, discovering what is happening to paddlefish in the rivers near Pittsburgh is serious business. And the 26-year-old Frostburg, Md., native now living in State College, Pa., -- who soon will be tacking up the signs wherever he can along the river -- intends to find out. It's all part of a joint project involving Penn State, California University of Pa. and the Pennsylvania Fish & Boat Commission.

A species that is believed to be more than 300 million years old -- older than the dinosaurs -- the paddlefish is native to the Ohio River and is still commonly found in West Virginia waters and farther downstream. But for some unknown reason -- perhaps pollution -- they disappeared before 1920 from stretches of the Ohio along Pennsylvania and in the Allegheny River, where they once had thrived.

The Fish & Boat Commission embarked on a restoration program in 1991 and has stocked about 75,000 10-inch-long paddlefish obtained from the West Virginia Department of Natural Resources in the last decade or so. But after disappearing in the murky greenish-brown depths of the river, the little "paddles" rarely have been seen again.

"It's a mystery -- what happens to them?" says Barry, a graduate student studying fisheries science in Penn State's College of Agricultural Sciences. "They are big enough not to be eaten by most predators in the river, but we wonder -- are we just feeding the huge flathead catfish? There have been reports of paddlefish sightings and collections over the past few years, but most are unsubstantiated. I think a lot of times people see them and catch them and don't know what they are."

But few paddlefish are caught by anglers, mostly because they mainly eat tiny zooplankton. "It's kind of ironic that the fish with the potential to grow the largest in the Ohio River eats the smallest food source," says Barry. "There are historic photos of paddlefish from the Mississippi that are 7 feet long, almost 200 pounds. The world record is 142 pounds, snagged by an angler on the Missouri River."

The paddlefish's long snout, called a rostrum, is a sort of super-sensitive antenna that can detect the minute electrical signals emitted by zooplankton movements, helping the fish to locate their food.

Barry suspects that a residual paddlefish population could have survived all along in the Pennsylvania portion of the Ohio, but proving it is difficult. "In our experience, when paddlefish die they sink instead of floating up and washing onto a shoreline," he says. Penn State and the Fish & Boat Commission have settled on a high-tech method to track stocked fish, and despite early difficulties, Barry is optimistic it will work. But it requires him to be a fish surgeon.

"Just call me Dr. Barry," he jokes. "I do a surgical procedure on some of the little paddlefish to implant small radio transmitters inside their body cavities prior to release, and then we track them.

"Surgeries are done under water so the fish is breathing all the time," Barry adds. "A helper holds the fish, another hands me sterile tools and a third retrieves fish. After surgery, fish are observed for 24 hours to ensure that they have completely recovered from surgery. I administer anesthesia, make the incision in the abdominal cavity, insert the transmitter with the antennae sticking out the side of the fish, and suture the cut. We've been pleased that our 48-hour mortality after surgery has been zero."

The transmitter used for the small paddlefish is about the diameter of a pencil and about an inch and a half long. Each one emits a unique frequency signal so Barry can track individual fish. The batteries that power the transmitters normally last at least a month.

Last July Barry tried to track 12 paddlefish in which he had implanted transmitters in a deep pool in the Ohio where they were released. "We don't know if it was because of transmitter failure or not, but two days later we were able to find just two fish, and two days later those signals disappeared," he says. "It was frustrating. We even flew over the river in a Cessna trying to pick up a signal."

He had more success last September. He implanted transmitters in 32 paddlefish and over the next two and a half months recorded more than 700 fish locations while tracking. His research will continue this summer when he plans to track 36 fish.

"We may choose transmitters that turn on and off to save battery life and allow longer monitoring," says Barry. "We also will be trying to capture paddlefish without transmitters in gillnets and perhaps with electrofishing gear."

It takes paddlefish about a decade to become sexually mature, so the fish stocked early in the Fish & Boat Commission's restoration program may produce offspring this spring. With high hopes and a little patience, Barry will be searching the shallows to see if he can find any tiny paddlefish. He says Penn State is considering a continuation of his research after this summer.

"One way or the other," he says, "we're going to find out what is happening to the paddlefish."

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EDITORS: Patrick Barry can be contacted at 814-865-3972 or paddlefish@psu.edu.

Contact: Jeff Mulhollem jjm29@psu.edu 814-863-2719 814-863-9877 fax #105