Thaleichthys pacificus
Eulachon are an anadromous (moving between freshwater and saltwater) smelt in the family Osmeridae. The binomial species name is derived from Greek roots; thaleia meaning rich, ichthys meaning fish, and pacificus meaning of the Pacific.
Eulachon are found from northern California to southwest Alaska. The southern distinct population segment (DPS) is listed as threatened under the Endangered Species Act.
Eulachon have many other names—smelt, hooligan, oolichan, and fathom fish. First Nations people called eulachon "salvation" fish because the return of spawning runs to coastal rivers meant the difference between life and starvation after a hard winter. Native people continue to fish for eulachon by traditional methods for use as an important subsistence food and medicine.
NOAA Fisheries is committed to conserving and protecting eulachon. Our scientists and partners use a variety of innovative techniques to study, learn more about, and protect this species.
The 2010 status review concluded that the southern DPS of eulachon experienced an abrupt decline in abundance throughout its range, beginning in the mid-1990s. Although eulachon abundance in monitored rivers improved in the 2013–2015 return years, sharp declines in eulachon abundance occurred in monitored rivers in 2016–2018. Recent improvements in ocean conditions in the northern California Current, beginning in 2020, suggest that eulachon may rebound in numbers in the near future. The 2016 ESA five-year review concluded that the DPS’s threatened designation remained appropriate. An updated five-year review is in preparation.
Eulachon are an anadromous smelt in the family Osmeridae and are distinguished from other osmerids by having 4–6 gill rakers on the upper half of the gill arch (others have 8–14 gill rakers) and distinct concentric striations on the operculum and suboperculum (gill plate). Eulachon have a prominent adipose fin, and exhibit strong countershading on the body; blue above and silver below. Eulachon mature when they are about 160–250 mm (6–10 inches) in length. Small, pointed teeth occur on both jaws and tongue, but these are usually resorbed in spawning specimens.
Juvenile eulachon from 30–100 mm in length disperse within the first year of life to open, marine waters on the continental shelf and reside near the bottom at depths of 50–200 m. Eulachon do not undergo diel vertical migrations from their preferred depths. Postlarval and juvenile (20–157 mm) eulachon consume various planktonic crustaceans, particularly adult copepods. Adult eulachon consume euphausiids, cumaceans, and copepods, with euphausiids (aka, “krill”) being the primary prey.
The Southern distinct population segment of eulachon can be found in the northeastern Pacific Ocean from the Mad River in northern California to the Nass River in British Columbia.
World map providing approximate representation of the eulachon ESA-listed population's range
Adult eulachon typically spawn at age 2–5. Many rivers within the range of eulachon have consistent yearly spawning runs; however, eulachon may appear in other rivers only on an irregular or occasional basis. The spawning migration typically begins when river temperatures are between 0 and 10⁰ C, which usually occurs between December and June. Most eulachon are semelparous (i.e., they die after spawning) and females release from 7,000–60,000 eggs, which are approximately 1 mm in diameter. Milt and eggs are released over sand or coarse gravel. Eggs become adhesive after fertilization and hatch in 3–8 weeks depending on temperature. River flow carries newly hatched larvae (4–8 mm in length) down-river to estuaries, and juveniles disperse onto the marine continental shelf within the first year of life.
The 2010 status review categorized climate change impacts on ocean conditions as the most serious threat to the persistence of eulachon throughout the Southern DPS. Climate change impacts on freshwater habitat and eulachon bycatch in offshore shrimp fisheries were also ranked within the top four threats in all areas of the DPS. Dams and water diversions in the Klamath and Columbia rivers, and predation in the Fraser River and British Columbia coastal rivers filled out the last of the top four identified threats.
| Kingdom | Animalia | Phylum | Chordata | Class | Actinopterygii | Order | Osmeriformes | Family | Osmeridae | Genus | Thaleichthys | Species | pacificus |
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