Green+Sturgeon

__**Basic Information:**__
 * Scientific name:** //Acipenser medirostris//
 * Scientific Classification:**
 * = **Domain** ||= Eukarya ||
 * = **Kingdom** ||= Animalia ||
 * = **Phylum** ||= Chordata ||
 * = **Class** ||= Actinopterygii ||
 * = **Order** ||= Acipenseriformes ||
 * = **Family** ||= Acipenseride ||
 * = **Genus** ||= Acipenser ||
 * = **Species** ||= medirostris ||

__**Habitat:**__ Green sturgeon can be found in marine waters around the Aleutian Islands and the Gulf of Alaska, as well as bays and estuaries down the west coast of North America, and as far south as Ensenada, Mexico. After breeding in freshwater, the green sturgeon moves to sea in late autumn to early winter, when temperatures drop below ten degrees Celsius and water flow increases. In the estuary, it is possible that green sturgeon are capable of moving across highly physical gradients in salinity, temperature, and dissovled oxygen. Green sturgeon in marine are usually found at depths of 20-60 meters and from 9.5-16.0 degrees Celsius. Green sturgeon may have behaviors that reduce the risk of predation by creatures, such as pinnipeds or sharks by avoiding detection while in structured areas or by migrating in a direction that contrasts with other temperate marine animals. The green sturgeon has no scales, instead it has scutes loacted along their bodies. Scutes are actually large modified scales, that serve as a type of armor or protection. __**Species Interactions:**__ Green sturgeon are consumers in their food chain making them carnivores. They have a diet that includes invertebrates such as shrimp, crabs and worms, as well as small fish. But they are not top level predators, instead those that prey on green stugeon are pinnipeds and sharks. Green sturgeon avoid them at all cost from being a prey of either predators. Green sturgeon has an unusual way of feeding, to feed they have a shovel-like snout and vaccum cleaner-like mouth that it uses to siphon food from the river and or marine bottom. __**Reproduction:**__ Green sturgeon can live up to 70 years and may spawn several times during their long lives, returning to the rivers every 3-5 years. After hatching, larvae and juveniles migrate downstream toward the Sacramento-San Joaquin Delta and Estuary. After being in the Delta and Estuary for several years, they move out to the ocean. Males and females cast eggs and sperm into the fast moving water. Fertilized eggs will sink to the bottom and stick to the gravel bottom where they'll stay until they hatch. It may take a green sturgeon 10 years to become sexually mature. Once mature, they mate only every 4 to 11 years. A single female green sturgeon can produce several million eggs. Most of the eggs will either be lost in the current or eaten by predators. Although the green sturgeon has a large population, ranging from the tens of thousands, there are concens about the loss of spawning sites of this species. Not only does green sturgeon breed in three rivers, but the thought of that four out of seven spawning sites have been lost. The green sturgeon's requirement to migrate to freshwater rivers from coastal areas makes it particularly vulnerable to human activities. With rivers being blocked, due to damming, channelling, and water extraction restricts this species access to breeding sites and can destroy existing sites. Green sturgeon can be divided into two distinct breeding population; one in the northern part and one in the southern part. Most individuals occur in the northern population, where the largest number of spawning females are found in the Klamath River. While in the southern population, it is unstable because poor land has greatly impacted the number of breeding green sturgeons and has restricted them to just the Sacramento River. Fishing was once a great threat to the survival of the green sturgeon. Fishing reached a high in 1986, when 10,000 individuals were taken. Because of fishing regulations, this threat has been reduced greatly and the estimated number of fish caught each year is probably around six percent of that taken in 1986.
 * __Threats:__**