Pursuing the Paddlefish

Liliana M. Naydan
January 11, 2003

It was early afternoon by the time I met Patrick Barry at the Harmar Marina on the Allegheny River just north of Pittsburgh. The sun was bright and the November air was unusually warm, and Barry, a Penn State graduate student in wildlife and fisheries science, had already maneuvered his 18-foot aluminum motorboat down the ramp and into the murky water. I stepped in carefully and sat down in the back, facing what looked like an old-fashioned metal rooftop antenna. It was rigged to the front deck off the bow and held together at its joints with strips of duct tape. A small black pirate flag tied to the top of one of the antenna's arms waved in the breeze as we shoved off in search of paddlefish.

man in life vest standing on shore and putting away boating equipment
Liliana M. Naydan

Returning to harbor after a day of tracking paddlefish

The paddlefish, which gets its name from its oddly shaped snout, or rostrum, is the oldest living animal in North America. "They're older than dinosaurs," says Barry, and they look like sharks. They can grow to seven feet long, and like sharks, have skeletons made entirely of cartilage. The paddlefish's nubbly, slate-gray skin has no scales. "They swim like sharks, too," says Barry. "They kind of cruise."

Paddlefish are hard to catch. That's due, in part, to a set of highly receptive sensory organs, pinholes that dot the underside of the rostrum. These sensors detect the slightest motion and are key to the creature's survival. With their beady eyes, Barry explains, paddlefish can't see very well. "But they can sense the movement of plankton floating downstream. I even heard that the Navy is studying the paddlefish rostrum to develop navigation technology."

This sensitivity may also explain the fish's disappearance from western Pennsylvania. By 1919, paddlefish, which continue to thrive in the other main branches of the Mississippi River, were rarely seen in the Allegheny. Barry speculates that turbulence from heavy boat traffic and man-made dams chased the ancient species into backwater areas where large boats can't travel. To test the theory, he and the Pennsylvania Fish and Boat Commission are fitting hatchery-born paddlefish with radio transmitters, releasing them into the river, and tracking their movements. They hope to learn enough to one day successfully repopulate the rivers in the state with these fish.

"When's the last time we had a sighting?" Barry yelled over the humming of the motor to Justin Lorson, a research technician and recent graduate of Mansfield University who was sitting at the front of the boat recording data. Lorson flipped through the pages of his little yellow notebook.

river in foreground with houses overlooking the river in the background
Liliana M. Naydan

Houses line the bank of the Allegheny River

"October twenty-first," he hollered back. Though they'd successfully plotted the underwater locations of all 34 radio-implanted fish they'd released, it had been two weeks since they'd seen one come to the surface.

"Listen," Mark Gritzer said. Gritzer, Barry's other research technician and a graduate of the California University of Pennsylvania, was holding up a black radio receiver that was hooked by cable to our ramshackle antenna. He listened to the receiver beeping as he spun the antenna to catch any fish's signal. When the antenna pointed toward the fish, the receiver's beeps grew louder.

"It's radiotelemetry," Gritzer explained. "The static's bad 'cause we're right near the turnpike, but if you listen close you can hear a change in the intensity of the sound. It's like trying to tune in a radio station in your car. But instead of music we're listening for pulses."

He turned to Barry. "Slow down, Pat, it's right back there."

Barry steered the boat around and cut the engine. "He's at twenty-six feet," Barry said, indicating the fish's depth directly below us.

"It's Hollywood," Barry said, calling the fish by the name he had given it after six weeks on the river. "This is right where we found him yesterday." To pinpoint the location, Barry noted the boat's proximity to familiar houses along the shore. He started the motor again and I got a whiff of gasoline as we sped off after our next quarry.

"Want to try tracking?" Gritzer asked once we'd been cruising a while.

I said I did. Gritzer moved aside and I stood and grabbed the antenna's lowest arm as a turning handle.

"Where's the most intense sound?" he asked as I spun the antenna.

three men in life vests standing on shore and holding antennas
Liliana M. Naydan

Justin Lorson, Mark Gritzer, and Patrick Barry

I listened to the changing strength of the beeps. "That way," I answered at last, pointing toward the near riverbank.

"Well tell him to go there," he said, nodding at Barry.

"Hey Pat, head that way!" I yelled over the motor's roar.

Barry turned the boat, drew close to shore, and stopped. Lorson penciled the location into his notebook.

"Radiotelemetry: Now you can put that on your resume," Gritzer said with a laugh. "Now give it a rating," he added, meaning the one-to-five scale the team uses to indicate confidence in the accuracy of a location.

"This one's a five," Lorson blurted before I could speak.

"Why a five?" I asked, wondering how they could be so sure I'd accurately tracked a fish on my first attempt.

"'Cause this one's dead," he answered grinning. "It's been in this same spot for weeks."

Barry chuckled and started the motor, then drove us down river to track our next fish.

Patrick Barry will receive an M.S. in wildlife and fisheries science in May 2004 from the College of Agricultural Sciences. His adviser is Robert F. Carline, Ph.D., 113 Merkle Bldg., University Park, PA 16802; 814-865-4511; rcarline@psu.edu. Barry's research is funded by The Pennsylvania Fish and Boat Commission.

Last Updated January 20, 2005