Tagging Tiny Fish: Scientists Aim To Learn More About Lamprey Migration
If Northwest fish were stand-up comics, the salmon would be the headliner. And the fish that gets “no respect” would be the lamprey, an eel-like creature that has been plying the Northwest’s rivers for 400 million years.
While millions of dollars have been poured into juvenile salmon research, much still isn’t known about juvenile lamprey. But now, scientists at the Pacific Northwest National Laboratory are tagging these small fish to learn more about how tiny, young lamprey swim downstream to the ocean.
“Are they actively migrating? What’s their travel rate? How fast do they swim when they are out-migrating? You know, how they pass the dams is a big unknown,” said Robert Mueller, a senior fish biologist with the lab.
If scientists can figure out how lamprey behave around dams, they might be able to design better bypass systems for the tiny young fish.
Tiny tags, smaller batteries
The tag is the size of a grain of rice. It’s the smallest fish tag being used as part of PNNL's larger Juvenile Salmon Acoustic Telemetry System.
The tags have to be so small and light because the fish the scientists are trying to study are so small. While they can grow to be as large as a woman’s arm, the juvenile lamprey that were tagged this year was only about five inches long.
The lab has been developing the tags since 2001, but this year is the first time its lamprey tag has been tested in the field. Scientists tagged 100 fish this year and were able to track 98.
The tags are also being tested back East in American eels.
The lamprey were captured at John Day and McNary dams on the Columbia River and they were returned after surgery between those two dams.
The scientists set up sensors to track them in the water column at several points downstream.
Each tag can ping every five seconds with a unique acoustic signal for about 30 days. Daniel Deng, the head mechanical engineer working on the tags for PNNL, said the lithium battery in the tags is the smallest micro-battery of its kind in the world to his knowledge.
Deng said lamprey are much like salmon. They rear their young in small tributaries. Then after several years those young lamprey migrate out to the ocean. The adults attach themselves to a fish and feed for years. Then, they return to the river and smaller tributaries to spawn and die.
Scientists aren’t too worried that a human will eventually eat the tag -- because the tags are placed in the body cavity of the fish -- and humans usually just eat the muscle meat of the fish.
An important, traditional food
Ron Suppah, councilman with the Confederated Tribes of Warm Springs in Oregon, says lamprey are a very important food to tribes—one of their “first foods.”
“The fish is always the first food, deer meat second, roots third, huckleberries are the fourth and water encompasses all of that,” Suppah said.
Suppah said the lamprey’s importance goes back to the time of creation.
“The Creator placed us on this part of the land, and gave us a voice,” Suppah said. “And the Creator gave us everything that would sustain us on the land. The foods are in the order of which they arrive in the seasons. We promised that we would take care of the foods forever. And if we neglected the foods, then the Creator would take them back and make them scarce.”
Suppah said the tribes and the federal entities have been working well together for restoration of the lamprey.
The U.S. Army Corps of Engineers have spent millions of dollars on lamprey passage past the dams. And Suppah said they are further working on better passage systems for the juveniles.
But he said the Columbia River is still tough on young lamprey. They have to go through dam gates or turbines. And get past many predators.
Lamprey are considered by many tribal people to be an actual medicine—something that will give better health. And some tribal people consider them to be an aphrodisiac.
“I love lamprey,” Suppah said. “I’ve fished for them every since the early 60s clear up to today. I can eat two to three eels at a sitting and feel good about it. Beats the heck out of two bowls of green salad.”
‘Really resilient critters and adaptable’
But Suppah said the lamprey were once easier to catch.
“In the 60s we would fish them, and they were so plentiful,” he said. “We would take 20 50-pound sacks. Now we take a half-tote full, like 10 sacks.”
And Suppah said it’s also getting harder to convince younger people to continue the hard work of fishing for lamprey.
“A lot of them [younger people] don’t care for the taste of them,” he said. “So why get something you don’t like to eat?”
Still, they are a very good source of oily fats, and rich flavors.
But to survive, lamprey need clean rivers and streams—and a better way past massive dams.
“We consider the lamprey our sisters,” Suppah said. “We have to make sure everything is healthy here for them to survive.”
Despite being somewhat snake-like, slippery and unattractive, Suppah said you have to ultimately respect the ancient lamprey. They’ve been on earth longer than dinosaurs.
“What I appreciate most is they are really resilient critters and adaptable,” he said. “They survive no matter how they got to do it.”