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Missouri Researcher Tracks Wandering Paddlefish

July 23, 2008

Long after Missouri’s spring paddlefish-snagging season ended, Josh Lallaman is still chasing the giant creatures.

Five days a week, he launches his boat on the Osage River and follows fish that he implanted with radio transmitters back in March.

His goal? To unravel some of the mysteries surrounding one of Missouri’s biggest fish.

“We knew before we even started this project that paddlefish are capable of traveling great distances,” said Lallaman, a graduate student in the University of Missouri’s fisheries and wildlife department. “And we’ve certainly seen that in our tracking study.

“They’re capable of traveling 35 to 40 miles a day, especially when they’re making their spawning run. That can make them hard to find at times.”

But like a good private eye, Lallaman has managed to keep up with most of the paddlefish he is tailing.

He uses sophisticated radio telemetry equipment to track the signals given off by the transmitters that he surgically implanted in 35 fish.

That’s what he was doing on a warm spring day. As Lallaman guided his boat into a stretch of water below Bagnell Dam, the signal on his radio telemetry receiver suddenly grew louder.

One of the paddlefish he was following had to be close.

“Each one of the paddlefish that we implanted with transmitters has a different signal,” Lallaman said. “That’s 101, a male that weighs about 30 pounds.

“He’s about 80 miles from the spot where we tagged him. He’s just been steadily working his way upstream.”

Once, such upstream migrations were common on the Osage River.

Before dams were built, large numbers of paddlefish would make long migrations up the river and spawn on gravel bars. Now, that path is interrupted, and there appears to be little natural reproduction.

The Missouri Department of Conservation has compensated for those losses by stocking thousands of paddlefish in the Lake of the Ozarks, Truman and Table Rock reservoirs.

Lallaman’s study, which is being conducted in conjunction with the Department of Conservation, is designed to determine whether there is any natural reproduction and also to learn more about the paddlefish’s movement patterns, its habitat and its needs.

“We do know that they are finicky spawners,” Lallaman said. “Traditionally, they always spawned after a big rise. Now that we have the dams, we don’t see that as often.”

But the paddlefish still go through the motions, making a false spawning run. Triggered by rising water temperatures, they work their way upstream in rivers such as the Osage each spring.

That’s when snaggers enjoy success, catching fish as big as 100 pounds. That’s also when Lallaman is busy keeping track of the fish he implanted with radio transmitters.

One of his first findings? That the paddlefish can be elusive during the snagging season.

“When we first tagged the paddle-fish this spring, they weren’t that active. The water was still cold,” Lallaman said. “On opening day of the snagging season, there were 15 to 20 boats working the stretch of water holding some of the fish we were following.

“We had boats pass right over some of the fish that we had tagged, but no one caught one.”

By the end of the snagging season April 30, only four of the 35 fish Lallaman was following had been caught. Since then, the survivors have shown a variety of habits.

Remember 101? Well, that little guy is a traveling man.

After navigating the 82 miles from the mouth of the Osage to Bagnell Dam, he has since swum all the way back down the river, into the Missouri and has kept right on going until he was out of Lallaman’s signal field.

“My guess is that he could be pretty far downstream in the Missouri by now,” Lallaman said.

If he is, he wouldn’t be the first paddlefish to travel great distances. One of the paddlefish that Lallaman tracked last year was found 280 miles away in the Mississippi River. That meant it had to travel through three river systems.

But not all paddlefish show that same wanderlust. Nine of the paddle-fish Lallaman is tracking have stayed in the water below Bagnell Dam.

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