Parasite of the Pacific
CENTRAL POINT — Standing in lower Jackson Creek with a long electric wand in hand, Ryan Battleson asks fellow state fish biologist Pete Samarin to turn on the electroshock contraption on his back.
"Set me to tickle, not stun," Battleson says.
Tickle it is, and later a small pulse of electricity jolts out of the mud a 3-inch version of perhaps the most fascinating yet least understood anadromous fish in the Rogue River Basin.
This young Pacific lamprey, called an ammocoete and as much as seven years away from becoming the parasite of the Pacific, swims to the surface and is netted by Samarin for quick identification and release back to the mud.
Chalk lower Jackson Creek to the list of Bear Creek Basin tributaries housing these little-known, eel-like parasitic fishes who are showing they are surviving in urban streams despite relatively poor water quality.
Samarin and Battleson are in the early stages of the first concerted effort to log lamprey-carrying urban streams within the Bear Creek Basin as part of a statewide effort by fish managers to understand where Pacific lampreys are and what it might take to keep them around.
Though long thought to inhabit the same streams as wild salmon and steelhead, lamprey seem to be declining, so the Oregon Department of Fish and Wildlife now is looking to get a better handle on where lamprey are and aren't.
A one-time candidate for federal Endangered Species Act protection, Pacific lamprey are listed in Oregon as a "sensitive" species.
"We're trying to figure out the next steps for monitoring and conservation," says Benjamin Clemens, an ODFW biologist now collating data for a lamprey assessment.
Locally, that means regular fish-shocking forays into local creeks to determine where juvenile lampreys are and what habitats they are using throughout this sliver of the Rogue Valley.
"These are some of the dirtiest urban streams," says Battleson as the caramel-colored Jackson Creek flushes past his waders. "If you can find them here, you should definitely find them in other valley tributaries."
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.
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 lampreys.
"We know they're out there, but nobody has a good testing protocol for these," Samarin says. "It doesn't exist."
Surveys in places like Little Butte Creek have turned up hundreds of lamprey ammocoetes, Battleson says. An hour spent shocking and prodding lower Jackson Creek yielded three.
"What constitutes a high density at this point? We don't know," Battleson says. "At this point, it's pretty much surveying for presence or absence."
By survey methods, the Jackson Creek work is rather low-tech.
In other surveys, electroshockers are set to stun fish so they rise to the top and can be counted and measured before they revive and swim away. For juvenile lamprey, the electricity dose is far less.
"We're really just tickling them," Battleson says. "The goal is not to immobilize them in the substrate because you won't even know they're there. It's just to agitate them and get them to swim to the surface."
Others are found by simply digging nets into the mud and sifting through the sediment for the squiggly juveniles.
"It takes a lot of work to find these things," Samarin says. "It's tough work."