Lamprey populations spawning in the Willamette River may display several
genetic differences, characterized by size and spawn timing, according to a
number one finding in the study was that Pacific lamprey in the Willamette
River displayed, to some extent, genetic differentiation, according to corresponding author Benjamin Clemens, a faculty
research assistant in the Department of Fisheries and Wildlife at Oregon State
University at the time of the study in 2009 and 2010.
neutral genetic loci, we found evidence for moderate genetic differentiation in
adult Pacific Lamprey collected at Willamette Falls,” Clemens said. “This is
surprising, given that previous genetic studies (that also used neutral loci)
have suggested little genetic differentiation among Pacific Lamprey, and that
Pacific Lamprey stocks are therefore fairly panmictic (random matings).”
2010, when the study’s researchers found evidence of genetic structuring of
adult Pacific lamprey at Willamette Falls, one genetic grouping was smaller and
migrated significantly earlier than the other, within-year genetic group.
Moderate genetic differentiation of the adult lamprey also occurred between the
years of the study – 2009 and 2010, Clemens added.
study in 2012 that used different genetic measurements found something similar,
Clemens said. In that study, small Pacific lamprey from Willamette Falls had
earlier passage times than large lamprey.
hypothesize that these data may indicate different migratory cohorts of Pacific
Lamprey,” Clemens said.
temporal genetic differentiation we report for Pacific lamprey in the Willamette
River is new, surprising, and biologically interesting,” the report says.
the aid of radio tags and fixed and mobile receiving stations (airplanes and
boats), researchers tracked lamprey movements in the Willamette River,
generating detailed migration histories for the 372 tagged lamprey.
?sh (69.9 percent) remained in the mainstem Willamette River; the remaining
30.1 percent migrated into tributaries,” the study says. “Eighty-two lamprey
exhibited multiple back-and-forth movements among tributaries and the mainstem,
which may indicate searching behaviors. All migration distances were
signi?cantly greater in 2010, when the amplitude of river discharge was
greater. Our data suggest genetic structuring between and within years that may
reflect different cohorts.”
to the study, the final detection for most lamprey were in the mainstem
Willamette, which suggests they may have spawned in the mainstem, died before
entering tributaries, or entered tributaries undetected.
for detections in tributaries, most lamprey were tracked in eastside
tributaries, such as the Santiam and the Molalla rivers. Of the westside
rivers, the Yamhill River had the most.
study found that some lamprey entered a tributary, then exited and then re-entered
the same or another tributary, sometimes multiple times, a back and forth
movement not detected in previous studies.
diversity does occur among adult Pacific Lamprey over dates within a year and
among years,” Clemens said. “These kinds of information provide some
tantalizing details and interesting nuances to show that lamprey are not boring
automatons that always migrate in a simple, ever-upstream path. And that the
genetics, body size, and behavior of a lamprey collected on a particular date
may differ from those of another lamprey collected on another date.”
study hypothesized that these back-and-forth movements may have been searching
behaviors by the lamprey for holding, rearing, or spawning locations.
genetic population structure and interannual variation in migration behavior of
Pacific Lamprey Entosphenus tridentatus” was published online January 27, 2017
in the journal Hydrobiologia (http://link.springer.com/article/10.1007/s10750-017-3096-4).
currently is a fish biologist and statewide lamprey coordinator with the Oregon
Department of Fish and Wildlife. His co-authors are Lance Wyss, currently a
restoration project manager for the Freshwater Trust. Rebecca McCoun is
currently a Council Coordinator for the North Santiam Watershed Council. Ian
Courter is a fisheries scientist for Mount Hood Environmental. Lawrence Schwabe
is a hydrosystem compliance specialist with the Confederated Tribes of the
Grand Ronde. Dr. Christopher Peery is currently a fish biologist with the U.S.
Fish and Wildlife Service. Dr. Carl Schreck is a University Professor and Unit
Leader of the U.S. Geological Survey Cooperative Fish and Wildlife Research
Unit in the Dept. of Fisheries and Wildlife at OSU. Erin Spice is a research
scientist and Dr. Margaret Docker is an associate professor, both in the
Department of Biological Sciences at the University of Manitoba.
study of lamprey migrating into the river was funded by the Columbia River
Inter-Tribal Fish Commission through the Columbia Basin Fish Accords with the
Bonneville Power Administration.
are an ancient taxonomic group that goes back about 500 million years, the
study says. Unlike salmon, there is little evidence that their migration return
from the ocean includes homing in on natal spawning grounds, but instead they
“may rely on other migration cues such as orienting to larval lamprey
addition, there is no evidence that Pacific lamprey have a fixed life cycle,
the study says. They have a long and variable (3 to 7 years) larval period in
fresh water before migrating to the ocean and to their parasitic stage when
they attach themselves to and feed on fish. That phase is about 3.5 years, but
smaller lamprey will return earlier. On their return to fresh water, lamprey
may hold in rivers anywhere from several weeks to a couple of years. They do
not feed prior to spawning and so will shrink in body size.
River Pacific lamprey, often considered one of the healthiest runs of lamprey
in the Columbia River basin, travel 205 kilometers (127 miles) from the Pacific
Ocean, 162 km (101 miles) in the Columbia River and 43 km (27 miles) up the
Willamette River to Willamette Falls where they congregate before continuing
their migration beyond the falls. The passage beyond the falls occurs mostly
April through late June.
population(s) – we don’t know whether it is best to label them as a single
population per se, at least not at this time – have declined significantly in
the Pacific Northwest (including the Columbia River Basin and Willamette River
Basin) over the last 100+ years,” Clemens said.
the late 1800s, one naturalist wrote about the abundance of Pacific lamprey at
Willamette Falls as being several layers thick in places, giving the impression
that the lamprey were a “profuse growth of kelp” in some areas of the falls,
some scientists have described lamprey at Willamette Falls as “the last
stronghold,” the abundance of the fish at the falls and all other areas of the
Columbia basin has declined significantly.
and lack of passage at certain dams, entrainment into water diversions and
screens as larvae, habitat degradation, pollution, dredging, decreases in ocean
prey sources that the lamprey parasitize, poor water quality, and many other
causes have been implicated to cumulatively be affecting populations of Pacific
Lamprey, Clemens said.
is “clear that many different Tribes rely on the availability of adult Pacific
Lamprey at Willamette Falls—where the lamprey congregate before ascending the
falls via lamprey ramps or via the fish ladder—as a source of harvest,” Clemens
continued. The fish are an important and integral component of tribal culture
lamprey continue to not get the attention they deserve, alongside ‘game’
fishes, there is evidence to suggest that waters that support robust lamprey
populations can support healthy salmon and steelhead populations, and vice
versa,” Clemens concluded.