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The Rogue's 'Third Tenor' sure can travel

I always look at the Cole Rivers Hatchery fish counts published Fridays in Oregon Outdoors and have always wondered whether Pacific lamprey make it up the Rogue River all the way to the hatchery. I remember seeing them climb on the concrete at Savage Rapids Dam when it was there. But with the removal of Savage Rapids and Gold Ray dams, are lamprey moving father upstream?

— Curt, Medford

Well, Curt, you latched onto an interesting aspect of Rogue River aquatic biology, citing perhaps the most famous of fishy parasites we have in the Pacific Northwest.

Pacific lamprey are the Rogue Basin’s anadromous fish version of the third tenor, with wild salmon and steelhead garnering all the attention among animals whose life cycle includes time in both freshwater and saltwater.

And just like salmon and steelhead, lamprey have been found at Cole Rivers Hatchery, says Dan VanDyke, the Oregon Department of Fish and Wildlife Rogue District fish biologist.

Early in his career in the late 1980s, VanDyke was a technician at Cole Rivers, where workers found young lamprey, called ammocetes, stuck in the screens at pond head gates. They had entered the hatchery’s water system either from Lost Creek Lake or the river between the hatchery and Lost Creek dam, he says.

“Basically, they go upstream as far as salmon and steelhead can,” VanDyke says.

A 2018 study by Ashland biologist Stewart Reid found them throughout the mainstem Rogue and in both Big Butte and Elk creeks, as well as in Bear Creek up to the Oak Street diversion in Ashland, VanDyke says.

Lamprey have a unique life history. Adults lay egg nests in some of the same gravel bars as wild salmon and steelhead, but their larvae quickly burrow into the creek substrate, where they will remain for up to seven years blindly feeding on algae, according to U.S. Fish and Wildlife Service data.

When they emerge and head to the ocean at about 6 inches long, they continue to feed on algae before turning parasitic. With their round, toothy mouths, they attach themselves to salmon, rockfish and other species while avoiding predators such as sharks and sea lions.

They can get to about 2 feet long before they stop feeding and head upriver to spawn. Using their mouths like suction cups, they can climb large distances over rock surfaces but can’t negotiate 90-degree turns because they lose that suction.

Little is known about their movements in specific streams such as the Rogue, because they move largely at night and regular counting methods for salmon don’t work well for lamprey.

A one-time candidate for federal Endangered Species Act protection, Pacific lamprey are listed in Oregon as a “sensitive” species.

Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@rosebudmedia.com. We’re sorry, but the volume of questions received prevents us from answering all of them.