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DID YOU KNOW? Green sturgeon are highly migratory in the ocean. Fish tagged in the Sacramento/San Joaquin estuary have been found in the Columbia River and Grays Harbor, Washington one year later.
SCIENTIFIC NAME: Acipenser medirostris, acipenser is an old world name for sturgeon and medirostris meaning moderate snout.
COMMON NAMES: Sakhalin sturgeon or sterlyad sturgeon.
DESCRIPTION: The green sturgeon is a primitive, bottom dwelling fish. It is characterized by its large size and long round body. There are four barbels located in front of its large toothless mouth located on the bottom (ventral) side of the head. The sturgeon has no scales, instead it has "scutes" (or plates) located along their bodies. Scutes are actually large modified scales, that serve as a type of armor or protection. Green sturgeon have 9-11 scutes on their back (dorsal) located in front of a single dorsal fin, 1-2 scutes trailing the dorsal fin, 23-30 scutes along the side, and 7-10 scutes on the ventral side. The dorsal body color is a dark olive-green, with the ventral surface a lighter whitish green, with the scutes having a lighter coloration than the body. Green sturgeon can reach 7 feet in length and weigh up to 350 pounds.
LIFECYCLE: Very little is know about the green sturgeon's life history. The green sturgeon is an anadromous fish that spends most of its life in salt water and returns to spawn in fresh water. It is a slow growing and late maturing fish that apparently spawns every 4 to 11 years during the spring and summer months. The green sturgeon spends limited time in fresh water; only while young and spawning. Adult fish and older juveniles are commonly found in estuaries and marine environments.
RANGE: In North America, green sturgeon are found from Ensenada, Mexico, to Southeast Alaska. Green sturgeon are not abundant in any estuaries along the Pacific coast, although they are caught incidentally in the estuaries by the white sturgeon fishery.
HABITAT AND ECOLOGY: Green sturgeon rely on streams, rivers, and estuarine habitat as well as marine waters during their lifecycle. Like the white sturgeon, greens prefer to spawn in lower reaches of large rivers with swift currents and large cobble; no nest is built, adults broadcast spawn into the water column. The fertilized eggs sink and attach to the bottom to hatch. Research indicates that water flow is one of the key determinants of larval survival. As a result, water diversions for municipal and industrial uses, irrigation projects, and power generation projects that reduce the amount of water in the rivers can negatively impact green sturgeon. Accumulation of PCBs and other contaminants can also reduce sturgeon survival.
Feeding on algae and small invertebrates while young, green sturgeon migrate downstream before they are two years old. Juveniles remain in the estuaries for a short time and migrate to the ocean as they grow larger. Adult green sturgeon feed on benthic invertebrates and small fish. The green sturgeon can become highly migratory later in life. They have been documented as traveling over 600 miles between freshwater and estuary environments.
ECONOMIC VALUE: The green sturgeon is commercially caught along with the white sturgeon in the Columbia River, Grays Harbor, and Willapa Bay. The green sturgeon is not as valuable as the white sturgeon because its flesh is considered inferior to that of the white sturgeon.