News
SpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliamentSpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliament
EveryFish
Male (bottom) and female (top) Sockeye salmon ( Oncorhynchus nerka ) specimens.

Oncorhynchus

A genus of migratory fish native to the North Pacific basin.

Photo: David Menke, Public domain, via Wikimedia Commons

Oncorhynchus is a genus of ray-finned fish in the family Salmonidae. It contains sixteen species of Pacific salmon and trout found in cold waters across the North Pacific.

Share on WhatsApp

  • Sixteen extant species of Pacific salmon and trout.
  • Males develop a hooked jaw called a kype for mating.
  • Most species are semelparous and die after spawning.
  • Body sizes have decreased due to overfishing and dams.
  • Hatchery fish compete with wild salmon for resources.

What it is

This group includes sixteen living species of ray-finned fish. They belong to the subfamily Salmoninae within the family Salmonidae. The name comes from Greek words for bend and snout. This refers to the hooked jaw called a kype that males grow during mating. These are mid-level predators found in cold water. Most live in the North Pacific basin. Some are landlocked in mountain lakes.

Where it lives

They inhabit tributaries of the North Pacific Ocean. Their range stretches from the Bering Sea south to Taiwan and Mexico. Most populations live in high-latitude cold waters. This includes the Russian Far East and the Pacific Northwest. Some cutthroat trout subspecies live in endorheic waters in the Rocky Mountains. Others have crossed the Continental Divide into the Mississippi River system. Rainbow trout and Chinook salmon have been introduced globally.

How it lives

Most species are anadromous or potamodromous. They display natal homing and semelparity. This means they die after spawning. Migration can be affected by parasites. Infected fish may become weak and fail to complete the journey. Steelhead trout are iteroparous and spawn multiple times. Coastal cutthroat trout are semi-anadromous. They spend time near their native streams. Parasites cause culling effects on infected individuals.

Breeding and life cycle

Pacific salmon are semelparous and die after spawning. Kokanee sockeye evolve differently from anadromous forms. They reach biological species status through reproductive isolation. Populations in the same lake spawn at different times. They eat different foods and do not interbreed. This resource partitioning allows them to coexist as independent genetic entities.

Oncorhynchus
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

Pacific salmon are harvested worldwide for food. Commercial and recreational fishing has increased significantly since the 1970s. Overfishing has led to smaller body sizes in many species. Smaller fish produce fewer offspring. Hatcheries play a major role in supplying fisheries. Hatchery fish often compete with wild salmon for resources. They may also exhibit predatory behavior toward wild stocks.

Status and threats

Populations have declined since the mid-nineteenth century. Columbia River stocks dropped below twenty percent of pre-1850 levels by 1933. Many runs are now dominated by hatchery-raised fish. Several subspecies are listed as endangered or extinct. Causes include overfishing, habitat loss, and hybridization. Conservation efforts face financial pressures from commercial interests. Sustainable certifications exist but are periodically reviewed.

Cover art of female Oncorhynchus rastrosus by Ray Troll.
Cover art of female Oncorhynchus rastrosus by Ray Troll.. Photo: Kerin M. Claeson, Brian L. Sidlauskas, Ray Troll, Zabrina M. Prescott,, CC BY 4.0, via Wikimedia Commons
" a Mean fish length has changed in a nonlinear pattern, as demonstrated by the nonlinear year effect from GAMs on mean population length with fixed effects of region and population. b Mean freshwater age (in years) has
" a Mean fish length has changed in a nonlinear pattern, as demonstrated by the nonlinear year effect from GAMs on mean . Photo: Authors of the study: K. B. Oke, C. J. Cunningham, P. A. H. Westley, M, CC BY 4.0, via Wikimedia Commons
"Salmon body size declines over the past 30 years have negative consequences for a fecundity, b nutrient transport, c commercial fishery value, and d rural food security. We estimated the difference in ecosystem services
"Salmon body size declines over the past 30 years have negative consequences for a fecundity, b nutrient transport, c co. Photo: Authors of the study: K. B. Oke, C. J. Cunningham, P. A. H. Westley, M, CC BY 4.0, via Wikimedia Commons
USFWS Headquarters Status: Threatened Photo credit: Joe DiSilvestro
USFWS Headquarters Status: Threatened Photo credit: Joe DiSilvestro. Photo: U.S. Fish and Wildlife Service Headquarters, Public domain, via Wikimedia Commons

Questions people ask about Oncorhynchus

What does the name Oncorhynchus mean?

The name derives from Ancient Greek words meaning bend and snout. It refers to the hooked lower jaw tip known as a kype. Males develop this feature during the mating season.

Are all Oncorhynchus species migratory?

Most are anadromous or potamodromous. Some cutthroat trout subspecies are landlocked. Steelhead trout are iteroparous and spawn multiple times. Coastal cutthroat trout are semi-anadromous.

Why are Pacific salmon getting smaller?

Overfishing selects against larger fish. Dams and climate change also contribute. Smaller fish have lower reproductive success. This trend affects population growth rates.

How do hatcheries affect wild salmon?

Hatchery fish often out-compete wild salmon. They may exhibit predatory behavior. Genetic changes reduce fitness in the wild. This disturbs natural social interactions and resource use.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Oncorhynchus", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

Like Oncorhynchus

All salmon and trout
🇺🇸 United StatesCutthroat trout A group of Pacific trout native to western North America, known for red throat markings.Salmonid · Rivers and lakes · 1793 🇦🇹 Austria and 4 moreHuchen A large freshwater salmonid native to the Danube basin in Central and Eastern Europe.Salmonid · Rivers and lakes 🇬🇧 United Kingdom and 3 moreSea trout Anadromous form of brown trout that migrates between sea and rivers.Salmonid · Between sea and river WorldBrown trout A widespread salmonid with river, lake and sea forms.Salmonid · Rivers and lakes · 1758

More from Salmonidae

All of them
🇺🇸 United StatesApache trout A golden-spotted trout native to Arizona highlands.Salmonid · Rivers and lakes 🇺🇸 United StatesCisco Small salmonid fish of northern lakes and seasSalmonid · Rivers and lakes WorldTaimen Large freshwater salmonids native to EurasiaSalmonid · Rivers and lakes 🇬🇧 United KingdomSchelly Rare whitefish of the English Lake DistrictSalmonid · Rivers and lakes

Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

The weekly digest

Every Monday: the fish of the day, new pages on EveryFish, and the conferences and anniversaries of the week ahead.