DEBBIE ELLIOTT, HOST:
Paddlefish have been swimming in North American water since the time of the dinosaurs. The odd-looking, prehistoric fish are a threatened species in several states, including Minnesota. But they seem to be making a comeback. Reporter Hannah Yang, with member station Minnesota Public Radio, has more.
HANNAH YANG, BYLINE: Paddlefish really do look like they come from a different age. They have no bones, just cartilage, and they can be huge - 5 to 7 feet long, weighing 60 to 80 pounds.
(SOUNDBITE OF BOAT MOTOR RUNNING)
ANTHONY SINDT: There's no teeth, just a big, giant mouth.
YANG: That's Anthony Sindt of the Minnesota Department of Natural Resources describing the fish's paddle-shaped snout.
SINDT: The paddle, called the rostrum, it's actually electrosensory organ that helps them detect zooplankton.
YANG: Sindt's colleague, Hannah Anema, describes the smooth skin of the fish.
HANNAH ANEMA: You have, like, this really cool blue tone on them, and their backs get really dark. And then they actually have - I would almost compare to - like, leopard spots on their gill covers. And their fins are really, like, a purply mauvy color.
YANG: Sindt and Anema are boating up a stretch of the Minnesota River in the south-central part of the state. They stop periodically to drop a hydrophone into the water, which picks up signals from fish tagged with an ultrasonic transmitter. Sindt says each transmitter's ping is unique, like a barcode, and lets researchers know which fish they found.
SINDT: You know, it sounds the same to us, no matter what, but this is taking that acoustic signal and turning it into the data.
(SOUNDBITE OF PINGS FROM FISH SONAR)
SINDT: So that was another fish.
(SOUNDBITE OF WATER SPLASHING)
YANG: Paddlefish started disappearing a little over a century ago due to overfishing, habitat loss, water pollution, and the construction of dams, which limited their migration. But now paddlefish numbers are rising. So Anema and Sindt are tracking their movements to get a better idea of how many there are and where they're located. We travel a mile upstream to collect data from a stationary receiver attached to a highway bridge. Anema removes the receiver with a magnet while Sindt uploads the data into a laptop.
SINDT: Any tagged fish, or fish with a transmitter implanted in it, that swims near this bridge, if it emits the signal while it's somewhat nearby, that will pick it up, save the information of the fish number and the specific time. And then we can upload that data and use that from all the receivers throughout the river to better understand movement patterns of different fish species, such as paddlefish.
(SOUNDBITE OF BIRDS CHIRPING)
YANG: It isn't clear yet if paddlefish are spawning more here, migrating from somewhere else or both. But this stretch of the Minnesota River seems to be a favorite place for them to gather. Sindt says improved water quality and the removal of some dams appear to be helping.
SINDT: We can be hopeful that they will have access to important habitats and potentially help increase their abundance and the health of their population and the whole system. And I know it will do that for other species as well.
YANG: The resurgence of the strange-looking underwater behemoth has people taking notice.
DAVE LONG: This is a wild creature. Not the prettiest creature, but it's a very fascinating creature.
YANG: That's Dave Long, co-owner of Paddlefish Brewing Company. The taproom pays homage to its namesake, with a scrap metal art sculpture and a wall of photos of people holding paddlefish.
LONG: I think it's important as a person living as being in awe and wonder and learning and seeing all the weird, wild things we have right here in St. Peter. These paddlefish are living right under our feet.
YANG: And people here see them as a good sign for the health of the region's rivers.
For NPR News, I'm Hannah Yang in St. Peter, Minnesota.
(SOUNDBITE OF FLEETWOOD MAC SONG, "DREAMS") Transcript provided by NPR, Copyright NPR.
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