The female northern pike was 33 inches long when fisheries crews from the Department of Natural Resources in Baudette, Minn., tagged her May 3, 1996 in Zippel Bay of Lake of the Woods.
An angler reported catching and releasing the pike in March 2005, also in the Zippel Bay area.
Thursday, the same DNR fisheries crew caught the old girl again in a trap net while conducting a northern pike assessment on Lake of the Woods.
Now as then, they caught her in Zippel Bay.
She had grown only 5 inches in 15 years.
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According to Tom Heinrich, large lake specialist for the DNR in Baudette, it's difficult to say how old the pike is. Unlike most fish, pike don't necessarily grow at a rate that corresponds with their age. Heinrich said they might sample a 25-inch pike that's two years old, and the next 25-inch fish of the same gender will be 6 years old.
The only way to know for sure is to count the growth rings in a jaw bone, which requires killing the fish.
One thing's for sure, though, the tagged pike crews recaptured Thursday is a very old fish. She appeared to be in good health, Heinrich said, but hadn't yet spawned.
"Assuming it was a slow grower all the way up to the time we tagged it, at the very least this fish is like 22 years old," Heinrich said. "Considering that it took 15 years to grow from 33 to 38 inches ... I wouldn't be surprised if this was anywhere from 22 to 30 years old."
And what's the lifespan of a pike?
"Until today, I would have told you 15 to 20 years," Heinrich said. "Not all fish have the potential to get huge, and this fish is just a real good example of a general principle in biology: You can grow fast and die young or grow slow and live really long.
"I think this fish took that path to the extreme."
While every encounter with the pike occurred in the Zippel Bay area, Heinrich said the fish hasn't necessarily spent its entire life there. Research has shown that pike tend to return to where they were hatched, Heinrich said, so it's likely the fish just uses the same spawning site every year.
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Where she goes the rest of the year is anyone's guess.
"That's something we don't know," Heinrich said. "I suspect it wasn't just hanging out right in front of Zippel Bay its whole life. There's a lot of angling pressure there, and it would have been reported more than once."
The homing instinct, though, makes a strong case for protecting spawning sites.
"You don't want to rip every cattail" out of an area, for example, Heinrich said. "You're destroying a whole spawning run. It's not like these fish are magically going to go someplace else."
Heinrich said the Lake of the Woods pike assessment, which the DNR is scheduled to conduct every five years, has produced good numbers of fish, and one net Thursday yielded four northerns longer than 40 inches; they sampled six fish over 40 inches.
Regulations on Lake of the Woods require anglers to release all pike from 30 inches to 40 inches.
Besides Zippel Bay, DNR crews have sampled northern pike in Swift Ditch near Warroad, Minn., and the Baudette River, a Rainy River tributary. They plan to sample the Warroad River this week, Heinrich said.
The DNR hasn't tagged northern pike on Lake of the Woods since 1997, Heinrich said.
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"The odds we were going to see a tagged fish this year were pretty small," he said. "I would like to see a couple more."
Dokken reports on outdoors. Reach him at (701) 780-1148; (800) 477-6572, ext. 148; or send e-mail to bdokken@gfherald.com .
