Species: Acipenser medirostris

Coastal areas of North Pacific from Gulf of Alaska to southern California and Ensenada, Mexico; currently known to spawn only in the Sacramento and Klamath river systems in California and the Rogue River in Oregon (Houston 1988, Berstein and Bemis 1997, NMFS 2001). The possibility of current spawning in the Umpqua River, Oregon, is under investigation. There is recent evidence of limited green sturgeon spawning in the Eel River based on the collection of both adult and juvenile fish in the mid-1990s (see NMFS 2003). The species formerly spawned in the San Joaquin River in California (NMFS 2001). Green sturgeons are reported to spawn in the Feather River, but this has not been substantiated. The northern distinct population segment (DPS) ranges northward from the Eel River, California; the southern DPS includes drainages whose estuaries are south of the Eel River (NMFS 2003).<br><br>The largest spawning population is thought to occur in the Klamath River on the north coast of California (NMFS 2003). Juveniles are captured each year in the Klamath River and have also been found in the lower portion of the Salmon River (a tributary to the Klamath River). Adults occur in the Trinity River, a major tributary to the Klamath River, to Gray's Falls (rkm 69), but spawning can be confirmed only up to the Willow Creek trap (rkm 40).<br><br>In the Sacramento river system, spawning occurs predominantly in the upper Sacramento River, above Hamilton City and perhaps as far upstream as Keswick Dam (see NMFS 2003). Juveniles are found throughout the Delta and San Francisco Bay. Adults and juveniles occur throughout the upper Sacramento River (NMFS 2003).<br><br>The Rogue River recently was confirmed as a third spawning area; radio-tagged spawners moved upriver as far as rkm 39 (see NMFS 2003); juveniles are taken in beach seining efforts in the Rogue River estuary, and adults are taken in almost all of the Oregon coastal estuaries from the Chetco River to Nehalem Bay (see NMFS 2003).<br><br>In the mid-1930s, before Bonneville dam, green sturgeons were found in the Columbia River up to the Cascade Rapids; today they occur up river to the Bonneville Dam (rkm 235) but predominately in the lower 60 rkm. Tagging studies indicate a substantial exchange of fish between the Columbia River and Willapa Bay. The estuaries of Willapa Bay, the Columbia River, and Grays Harbor are late summer concentration areas. The reasons for these concentrations are unclear, but they do not appear to be related to spawning or feeding (NMFS 2003). <br><br>Small numbers have been taken in both Tomales Bay and Bodega Bay and a single fish has been taken from the Noyo River. Green sturgeons are regularly taken in small numbers in Humboldt Bay and have been caught in coastal waters and in estuaries from Arcata Bay to the Oregon border. Small numbers of both adult and juvenile green sturgeons have been observed in the Eel River (NMFS 2003). Green sturgeons occur in small numbers along the western coast of Vancouver Island and the Skeena River. Historically, they were not uncommon in the Fraser River. There is no evidence of historical or recent spawning in Canada (Trevor Davies, draft COSEWIC report, 2003).<br>