Tag: otolith

Research Results: If You Restore It, Will Pike Come?

It’s well known that some migratory fish species, like salmon, are able to trace their way back to the stream where they were born. However, conservationists have no idea if this is the case for hundreds of other fish species.

Do pike return to spawn in the streams where they were born, a la salmon?

Not necessarily, at least in the Green Bay watershed. If there’s suitable habitat, pike will find it and spawn. That’s the central finding of research conducted by the University of Wisconsin’s Pete McIntyre and Dan Oele.

This result may sound like a let-down, but in reality it’s a relief for conservationists in the Green Bay area. The Nature Conservancy and other conservation groups are focused on restoring streams for pike and other fish, but the best methods to accomplish that goal remain uncertain. If pike returned to their natal streams to spawn, they may never find a restored stream even if it contained suitable habitat.

That’s not the case, which is good news for conservation efforts.

Full Article

Big Fish: Roadside Pike

Northern pike have always conjured images of wilderness: big, wild lakes, the scent of pine trees, a loon calling in the background.

Large, predatory fish, pike do indeed hunt lake shallows. They’re found in big places—from remote Alaskan and Canadian waters to the Great Lakes.

Come spring, they actually are on the move—traveling up rather small streams in order to spawn.

Researchers in Green Bay, Wisconsin have been tracking pike movements by doing chemical analyses of pike otoliths, also known as ear stones. Otoliths have annual growth rings, like trees, and accumulate trace chemicals from the surrounding water column as they form.

Many streams have a specific—and unique—combination of chemicals, and this chemical profile shows up in the otolith when fish move from one chemically distinct water body to another.

As such, researchers can determine where pike spent different years of their lives – and if they return to the streams where they were born, or if they use different streams.

This knowledge, in turn, helps conservationists focus on restoring streams that will actually be used by pike.

When I headed out with researchers, I imagined we’d search for pike in wild, lonely places. Instead, we immediately drove to an area across from a small, rural housing development, cars whizzing by as we checked pike traps.

Where could the pike possibly be?

It turns out: In a roadside ditch.

These little ditches— the kinds designed to keep water off the road—have been used for a very long time by pike as spawning sites.

With hundreds of lakes, streams and wetlands within miles of Green Bay, it may seem odd to focus on ditches. But those little channels may be vital in restoring pike populations.

Full Article


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