Green Sturgeon (Acipenser medirostris)

A green sturgeon can live for 60 to 70 years, according to NOAA, spending long stretches in the Pacific before returning to a river to breed. This is a fish built for a long life, with much at stake when an adult is lost.

The green sturgeon, Acipenser medirostris, is a conservation species, not a commercial source of caviar. Its southern US population is federally threatened; its northern population is not ESA-listed.

Green sturgeon facts

The source record also contains the unlabelled entries “About 4.3 mm in breeding research” and “California, according to UC Davis”, each followed by “Not reliably established”. Their subjects are unclear, so they cannot be assigned to factual fields here.

Where green sturgeon live

Green sturgeon range along North America's Pacific coast, spending extensive periods at sea and using rivers, estuaries and coastal waters at different life stages. They are anadromous: they move between saltwater and freshwater to complete their life cycle. Their extensive use of the ocean distinguishes them from many other sturgeons. The sturgeon species guide places them within the wider family.

Northern fish spawn in Oregon's Rogue River and California's Klamath and Eel rivers, according to NOAA's current species account. Southern fish reproduce in California's Sacramento River system, including the Feather and Yuba rivers. Finding a fish in an estuary does not establish that it spawns there.

Both populations travel along the coast and can share feeding areas. In a study published in 2011, Lindley and colleagues fitted 355 green sturgeon with acoustic transmitters, then detected their movements with underwater receivers. The findings make the conservation challenge clear: spawning rivers and distant feeding grounds need protection as a connected network, not isolated sites.

Size, growth and reproduction

Green sturgeon reach maturity at around 15 years, according to NOAA. It gives an average length of about 1.4 to 2.0 metres, converted from its published range of 4.5 to 6.5 feet. Individual fish vary.

Adults survive reproduction and can spawn repeatedly. California's wildlife agency describes returns to spawning rivers every 2 to 6 years. With maturity so late and breeding opportunities spaced years apart, the loss of a mature fish carries particular weight.

How to recognise a green sturgeon

Start with the belly and barbels, not just the colour. Green sturgeon have an olive-green back and a pale belly with a dark stripe down its centre. Their four barbels, sensory feelers beneath the snout, sit closer to the mouth than to the snout tip. White sturgeon have barbels nearer the snout tip.

Both species carry rows of scutes, the bony plates along the body. Green sturgeon also have a conspicuous scute behind the dorsal fin. Use these features together, following agency identification guides; colour alone will not settle the identification. The white sturgeon profile covers the other Pacific coast species.

Two populations, different protections

The legal distinction follows breeding populations, not appearance. A distinct population segment, or DPS, is a population unit recognised for assessment under the US Endangered Species Act. These are not two separate species.

NOAA listed the southern DPS as threatened on 7 April 2006 and designated critical habitat on 9 October 2009. The northern DPS is not federally listed as threatened or endangered, but state fishing restrictions still apply.

Southern critical habitat extends far beyond the spawning rivers. It includes specified Sacramento basin waters and the Delta, coastal bays and estuaries, and marine waters from Monterey Bay to the Canadian border, generally out to the 110 metre depth contour. Together, these places support different stages of the fish's life.

US critical habitat designation does not ban all human activity. Federal agencies must consult the relevant wildlife agency and ensure that actions they authorise, fund or carry out are not likely to destroy or adversely modify designated critical habitat. In Canada, green sturgeon is listed as Special Concern under SARA, a category distinct from threatened or endangered.

Why protection is needed

A fish does not have to be kept to be harmed. Bycatch, accidental capture while fishing for something else, remains a threat where retention is prohibited: capture and handling can injure or kill green sturgeon. NOAA's conservation programme includes work with fishing fleets to reduce these encounters.

The river journey brings other pressures. Dams and altered flows can block access to spawning habitat or make it less suitable. Water diversions can entrain fish, drawing them into channels or infrastructure. Contaminants and warming water add to the burden. Recovery therefore involves fish passage, river flows, temperature management and habitat restoration, not simply restrictions on fishing.

Fishing restrictions and roe

Green sturgeon cannot be retained in recreational or commercial fisheries across California, Oregon, Washington and British Columbia, according to NOAA. The practical rules are clear:

• Oregon expressly prohibits targeting green sturgeon, even for catch-and-release.
• Washington also prohibits fishing for them.
• California requires accidentally hooked fish to remain in the water and be released immediately.

CITES Appendix II regulates international trade; it does not authorise domestic harvest. MED identifies the species, not an authorised caviar fishery.

Indigenous relationships and stewardship

For the Yurok Tribe, green sturgeon belong to a much broader story than roe. The Tribe identifies them among the Klamath Basin fishes important to its people for cultural, sustenance and ecological reasons. Tribal fisheries scientists also contribute to understanding the species.

Indigenous sturgeon traditions provides the wider cultural context.

The Sakhalin connection and changing names

Older literature sometimes placed the Asian Sakhalin sturgeon within green sturgeon, including under the name Acipenser medirostris mikadoi. They are now treated as separate species: Sakhalin sturgeon is Acipenser mikadoi. Read the Asian conservation profiles for its own history and status.

The green sturgeon's name also remains a subject of taxonomic debate. Brownstein and Near's 2025 proposal uses Sinosturio medirostris. At its October 2025 workshop, the IUCN Sturgeon Specialist Group did not accept that proposal. The original account also says that “both organisations” proposed an alternative classification at the same meeting, but does not identify both organisations clearly. This page retains Acipenser medirostris, the name used by the conservation and CITES sources cited here.