FISH MEETS RADIO, WITH BICYCLE
A study of big fish in the Rideau River may attract some glances, writes Tom Spears.
Sometimes a fish needs a bicycle. Or at least a conservation scientist on a bike.
In the Rideau River, pike and muskellunge with tiny transmitters are sending signals to biologist Steven Cooke of Carleton University. He sends out student Karsten Pankhurst on a bike with radio gear to map where the big fish go.
They especially want to learn whether fish will enter Brewer Park Pond once a culvert connects it to the river next fall.
Cooke planted radio transmitters in 20 pike and 20 muskies, and released them last summer. It’s a partnership with Muskies Canada and the Rideau Valley Conservation Authority. Cooke has a Canada Research Chair in fish ecology and conservation physiology. We asked him about the project.
Q: Why bother to track fish at all?
A: “Government likes to throw lots of money at restoration because it gives politicians something they can stand by. They can be beside something and have a
photo op. It’s a feel-good story. However, does it actually work? Are we using our limited resources appropriately?”
There’s a year of “baseline” data on fish movements between Hog’s Back and Rideau Falls. Once a culvert opens the way into the pond, the radio transmissions will show whether the fish enter the pond.
“We’ll probably tag some additional fish and move them right into the pond area, and look at how those animals use it.”
Q: Isn’t it a given that fish will swim into the pond?
A: Not this time. “The concept makes sense; however, for a variety of reasons the connection between the pond and the river itself isn’t quite as ideal as I had envisioned. It’s actually going to be a pipe that the fish have to swim through … and it will be a dark pipe. Fish don’t spend a whole lot of time swimming through pipes. They’re used to swimming in more open habitats. So, first they have to find it and second they have to be willing to explore it.”
Q: How do you put a radio transmitter on a fish?
A: “The best place to put a longterm tag is actually in the belly. We put the fish to sleep, we insert the transmitter and we sew the fish up. It is a surgical procedure. We worked with vets to optimize the procedure. Then the fish wakes up and it swims away.”
The transmitter works for about three years.
Each fish has a unique radio frequency and sends a beep every three seconds. Cooke’s cycling students carry equipment that receives the signals. They plot locations.
There are tricky aspects. Triangulation in water doesn’t work as well as on land. One curveball is that depth changes the signal: A signal can either indicate that a fish is in the shallow water near
one shore or the deep water on the opposite side. Cooke says there’s “a little bit of magic” in reading the beeps. Q: Do you name the fish?
A: No, they have numbers, “but there’s no doubt that each fish has its own personality. Some fish are homebodies, some fish are big movers. And there are some that we know are recaptured by anglers quite frequently, and others are caught by our electrofishing boat and never seem to be caught by the angling community.”
(Biologists send an electric shock through the water to stun fish and bring them unharmed to the surface. But they don’t get to keep what they catch.)
Another oddity: Muskies are considered the biggest and stron-
gest fish in the river. However, muskies hatch a little later than pike. That lag time gives pike a chance to grow big enough that very young pike eat very young muskie.
Q: Any more fish science going on?
A: Yes: Cooke and others are running an International Muskellunge Symposium at Carleton on Aug. 14-15. It’s open to the public. Information is at www.muskiescanada.ca/whats_new/symposium.php, or by email at musky. symposium@gmail.com. Q: Are you handing out maps of the muskies’ favourite hangouts? A: No.