PACIFIC LAMPREY
DID YOU KNOW: The Pacific Lamprey has no true fins, jaws,
or bones.
SCIENTIFIC NAME: Lampetra tridentata,
from the Latin lambere, to suck, petra meaning stone,
and tridentata meaning three-toothed.
COMMON NAMES: Pacific sea-lamprey, three toothed lamprey,
tridentate lamprey, and sea lamprey.
DESCRIPTION: The lamprey has a round, elongate, flexible
cartilaginous body, and skin with no scales. Lamprey are very
smooth and slimy to the touch. Its mouth is down-turned and adapted
for clinging and sucking. Pacific lamprey are a dark bluish gray
or dark brown in color and can reach 30 inches in length and weigh
over a pound.
LIFE CYCLE: The Pacific lamprey is anadromous. Like salmon
they are born in freshwater streams, migrate out to the ocean,
and return to fresh water as mature adults to spawn. Also like
the salmon, lamprey do not feed during their spawning migration.
Mating pairs of lamprey construct a nest by digging together
using rapid vibrations of their tails and by moving stones using
their suction mouths.
The lamprey enter streams from July to October; spawning takes
place the following spring when water temperatures are between
50 and 60 degrees Fahrenheit. They ascend rivers by swimming upstream
briefly, then sucking to rocks and resting. Spawning takes place
in low gradient sections of water, with gravel and sandy bottoms.
Adults die within four days of spawning, after depositing about
10,000 to 100,000 extremely small eggs in their nest. The young
hatch in 2-3 weeks and swim to backwater or eddy areas of low
stream velocity where sediments are soft and rich in dead plant
materials. They quickly burrow into the muddy bottom where they
filter the mud and water, eating microscopic plants (mostly diatoms)
and animals. The juvenile lamprey will stay burrowed in the mud
for 4 to 6 years, moving only rarely to new areas. After a two
month metamorphosis, triggered by unknown factors, they emerge
as adults averaging 4.5 inches long. Then during high water periods,
in late winter or early spring the new adults migrate to the ocean.
During its ocean phase of life the Pacific lamprey are scavengers,
parasites, or predators on larger prey such as salmon and marine
mammals. After 2 to 3 years in the ocean they will return to
freshwater to spawn.
RANGE: Baja California, to the Bering Sea in Alaska and
Asia.
HABITAT AND ECOLOGY: While in their 4-6 year larval stage
lamprey occupy a special niche in the stream system, filtering
microscopic plants and animals from the bottom sediments. They
fall prey to a wide variety of species including trout, crayfish,
and birds.
Lamprey have similar freshwater habitat requirements as do some
of the Pacific salmon, therefore they have encountered similar
habitat problems. Though absolute historical population sizes
of the lamprey are not known, it is clear that the fish, once
a significant tribal subsistence food, have shown severe decline.
Historical splash damming has scoured many of the stream bottoms
down to bedrock, removing necessary habitat. Dams can hinder
adult and juvenile passage or completely cut off prime spawning
habitat. Inappropriate logging and grazing practices can alter
stream flows and degrade habitat severely.
The first 4 to 6 years of the Pacific lampreys life are critical
times. Animals that filter water and mud for food are very susceptible
to pollutants in the water column and sediments. Lamprey may
be impacted by pollutants from urban and agricultural runoff that
can concentrate in the sediments. Because this species depends
on muddy bottoms, backwater areas, and low gradient areas during
its juvenile life stage, it is susceptible to loss of wetlands,
side channels, back eddies, and beaver ponds resulting from agricultural,
forestry or urban development practices or channelization for
flood control. High stream temperatures and lack of stream cover
can also reduce the lampreys' food supply.
ECONOMIC VALUE: The Pacific lamprey has little or no economic
value in the Pacific Northwest. Before its decline the lamprey
was a very important fish for many of the Tribal people of the
Pacific coast and interior Columbia River basin. Tribal people
harvested these fish for subsistence, ceremonial, and medicinal
purposes.
Revised 3/11/97
