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Pacific Lamprey

Entosphenus tridentatus

Fish · family Petromyzontidae · order Petromyzontiformes

  1. G1
    Critically imperiled
  2. G2
    Imperiled
  3. G3
    Vulnerable
  4. G4
    Apparently secure
  5. G5
    Secure

NatureServe global rank G4: apparently secure[2].

Updated October 30, 2026. Published by Humblebee.

Endangered Species Act
Not listed[1]
NatureServe global rank
G4 Apparently Secure[2]
Native in
5 states[3]
Longest recorded life
9 years[4]

The Pacific Lamprey is a jawless, eel-shaped fish in the family Petromyzontidae[5]. It is native to Alaska, California, Idaho, Oregon and Washington, and it is not listed under the US Endangered Species Act[3][1].

Conservation status

NatureServe ranks the Pacific Lamprey G4 (Apparently Secure) worldwide and N4 (Apparently Secure) in the United States[2][6]. The IUCN Red List category recorded by NatureServe is Least concern[7]. It is not listed as endangered or threatened under the US Endangered Species Act in USFWS data[1]. State ranks differ, and the table on this page lists them[8]. NatureServe estimates more than 1,000,000 adults worldwide[9].

Status Value
Endangered Species Act[1] Not listed
NatureServe global rank[2] G4 (Apparently Secure)
NatureServe US rank[6] N4 (Apparently Secure)
IUCN Red List (via NatureServe)[7] Least concern
Total population (NatureServe estimate)[9] >1,000,000 individuals

Where Pacific Lamprey lives

NatureServe lists the Pacific Lamprey as native in 5 US states and territories: Alaska, California, Idaho, Oregon and Washington[3]. Observation records on GBIF are most plentiful for Oregon, California, Washington, Alaska and Idaho, in that order[10]. These counts follow where people look and report, so they do not show how many animals live in each state[10]. The National Park Service records the species in 2 park units[11].

Alaska: native, state rank S4AKMaine: not recordedMEWisconsin: not recordedWIVermont: not recordedVTNew Hampshire: not recordedNHWashington: native, state rank S1WAIdaho: native, state rank S1IDMontana: not recordedMTNorth Dakota: not recordedNDMinnesota: not recordedMNIllinois: not recordedILMichigan: not recordedMINew York: not recordedNYMassachusetts: not recordedMAOregon: native, state rank S1ORNevada: not recordedNVWyoming: not recordedWYSouth Dakota: not recordedSDIowa: not recordedIAIndiana: not recordedINOhio: not recordedOHPennsylvania: not recordedPANew Jersey: not recordedNJConnecticut: not recordedCTRhode Island: not recordedRICalifornia: native, state rank S3CAUtah: not recordedUTColorado: not recordedCONebraska: not recordedNEMissouri: not recordedMOKentucky: not recordedKYWest Virginia: not recordedWVVirginia: not recordedVAMaryland: not recordedMDDelaware: not recordedDEArizona: not recordedAZNew Mexico: not recordedNMKansas: not recordedKSArkansas: not recordedARTennessee: not recordedTNNorth Carolina: not recordedNCSouth Carolina: not recordedSCDistrict of Columbia: not recordedDCOklahoma: not recordedOKLouisiana: not recordedLAMississippi: not recordedMSAlabama: not recordedALGeorgia: not recordedGAHawaii: not recordedHITexas: not recordedTXFlorida: not recordedFLPuerto Rico: not recordedPR
State presence as recorded by NatureServe[8].
Show state ranks (5 states)
StateRankMeaning
AlaskaS4Apparently Secure
CaliforniaS3Vulnerable
IdahoS1Critically Imperiled
OregonS1Critically Imperiled
WashingtonS1Critically Imperiled

Habitat

This fish uses both fresh water and the sea. NatureServe records big and medium rivers, creeks, riffles, pools, deep and shallow water, bays and sounds, river mouths, open ocean and near shore waters[12]. Young lampreys live in muddy, silty or sandy backwaters along the edges of streams[13]. Adults that go to sea feed mostly in the ocean near river mouths and other coastal areas, though sometimes farther away[13]. Adults spawn in clear streams with rock, sand or gravel bottoms, in shallow nests at the head of riffles[13].

Habitat types recorded by NatureServe[12]

Size, diet and lifespan

Adult Pacific Lampreys are parasites that attach to fish and feed on their body fluids[14]. This parasite stage may last 20 to 40 months[14]. NatureServe records adult food habits as piscivore, invertivore and herbivore[15]. The young, called ammocoetes, filter tiny plant and animal material from the water[14]. The typical length recorded by NatureServe is 76 cm (30 in)[16]. The longest recorded lifespan in the wild is 9 years, which is a record and not a typical lifespan[4]. Adults die soon after spawning[17].

Trait Value
Typical length[16] 76 cm (30 in)
Longest recorded lifespan (AnAge)[4] 9 years (wild)
Food habits[15] Piscivore, Invertivore, Herbivore
Migration[18] local migrant, long-distance migrant

When to look for it

Most Pacific Lampreys are anadromous, which means they hatch in fresh water, live in the ocean, then return to fresh water to spawn[19]. Upstream trips can be several hundred kilometers long, and NatureServe lists the species as both a local and a long-distance migrant[19][18]. Timing varies by place. Spawning happens in June and July in Washington, and in southern California it likely starts by late January and may go into April[20]. On GBIF, records peak in May, June and July, which reflects when people look and report[21].

January: 46 recordsJanFebruary: 38 recordsFebMarch: 86 recordsMarApril: 138 recordsAprMay: 186 recordsMayJune: 164 recordsJunJuly: 192 recordsJulAugust: 129 recordsAugSeptember: 95 recordsSepOctober: 58 recordsOctNovember: 35 recordsNovDecember: 23 recordsDec
US observation records on GBIF by month, all years. The three months with the most records are highlighted. Records show when people look and report, not how many animals there are[21].
Show records by month
MonthRecords
January46
February38
March86
April138
May186
June164
July192
August129
September95
October58
November35
December23

Where to see it

National Park Service species lists record Pacific Lamprey as present in 2 park units[11]. Present means the park has a confirmed record, not that sightings are common.

States with the most GBIF observation records: Oregon, California, Washington, Alaska, Idaho[10]. These counts follow where people look and report, not population size.

Questions people ask

Is the Pacific Lamprey endangered?
It is not listed as endangered or threatened under the US Endangered Species Act[1]. NatureServe ranks it Apparently Secure globally, but state ranks differ[2][8].
Where does the Pacific Lamprey live?
NatureServe lists it as native in Alaska, California, Idaho, Oregon and Washington[3]. It uses rivers, creeks, estuaries and the ocean[12].
What does the Pacific Lamprey eat?
Adults are parasites that attach to fish and feed on body fluids[14]. The young filter tiny plant and animal material from the water[14].
How big is a Pacific Lamprey?
The typical length recorded by NatureServe is 76 cm (30 in)[16].
How long does a Pacific Lamprey live?
The longest recorded lifespan in the wild is 9 years[4]. That is a record, not a typical lifespan[4].

Facts and sources

  1. Pacific Lamprey is not listed as endangered or threatened under the US Endangered Species Act in USFWS ECOS data (checked 2026-10-30). USFWS ECOS
  2. NatureServe global conservation status rank for Pacific Lamprey: G4 (Apparently Secure). NatureServe Explorer
  3. NatureServe lists Pacific Lamprey as native in 5 US states and territories: Alaska, California, Idaho, Oregon, Washington. NatureServe Explorer
  4. Maximum recorded lifespan in AnAge: 9 years in the wild. This is a record, not a typical lifespan. AnAge
  5. Pacific Lamprey (Entosphenus tridentatus) is a fish in the family Petromyzontidae, order Petromyzontiformes. NatureServe Explorer
  6. NatureServe national rank in the United States: N4 (Apparently Secure). NatureServe Explorer
  7. IUCN Red List category as recorded by NatureServe: Least concern. NatureServe Explorer
  8. NatureServe state ranks for Pacific Lamprey (map and table on this page). NatureServe Explorer
  9. NatureServe estimate of total adult population (global, as a range): >1,000,000 individuals. NatureServe Explorer
  10. US states with the most GBIF observation records of Pacific Lamprey: Oregon, California, Washington, Alaska, Idaho. Record counts follow observer effort, not population size. GBIF
  11. NPSpecies park lists recording Pacific Lamprey as present (list on this page). NPS NPSpecies
  12. Habitat types NatureServe records for Pacific Lamprey: Big river, Medium river, Creek, Moderate gradient, Riffle, Pool, Deep water, Shallow water, Bay/sound, River mouth/tidal river, Pelagic, Near shore. NatureServe Explorer
  13. NatureServe notes on habitat for Pacific Lamprey. NatureServe Explorer
  14. NatureServe notes on food for Pacific Lamprey. NatureServe Explorer
  15. Adult food habits recorded by NatureServe: Piscivore, Invertivore, Herbivore. NatureServe Explorer
  16. Typical length recorded by NatureServe: 76 cm (30 in). NatureServe Explorer
  17. NatureServe notes on phenology for Pacific Lamprey. NatureServe Explorer
  18. NatureServe migration category for Pacific Lamprey: local migrant, long-distance migrant (populations can differ). NatureServe Explorer
  19. NatureServe notes on migration for Pacific Lamprey. NatureServe Explorer
  20. NatureServe notes on reproduction for Pacific Lamprey. NatureServe Explorer
  21. GBIF observation records of Pacific Lamprey in the US by month (chart on this page). GBIF

Status, range and habitat come from NatureServe Explorer (CC BY 4.0) and USFWS ECOS at the snapshot date. Listings change by federal rule. State lists are where NatureServe records the species, not a promise that you will see it there. Never name a place smaller than a state. GBIF and park records count observations and checklists. They show where and when people report the species, not how many animals live there.

NatureServe. 2026. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org. (Accessed: October 30, 2026). Licensed under CC BY 4.0; SpeciesFacts selected and summarized it.