Sturgeon are modern relics of the ancient group of bony fishes, and have a skeleton that is mostly cartilage rather than bone and rows of bony plates for protection instead of scales. The sturgeon has a shovel-like snout and vacuum cleaner-like mouth that it uses to siphon food.

The green sturgeon spends the most time in saltwater of any of the three sturgeon that live part of their lives in the ocean. Green sturgeon tagged by the Yurok Tribe in the Klamath River system have ended up in Grays Harbor, Wash., about 60 miles north of Astoria, Oregon. Others have made it into Puget Sound. Just south of the Klamath River, green sturgeon can also be found in Humboldt Bay.

Green sturgeon spend a lot of time in river estuaries and in the ocean, moving upstream mostly to spawn. A few spawning sites have been identified, mostly on the Klamath River. One pool on the Klamath is known to be particularly active. Leaping and jostling fish crowd into a place called "The Sturgeon Hole," about a mile upstream from Orleans, California, in spring and early summer. To a lesser degree, spawning also occurs in the Sacramento River, especially in one of its tributaries, the Feather River, and in the Rogue River in southern Oregon.