GREEN STURGEON LISTING: NATIONAL MARINE FISHERIES SERVICE PROPOSES THREATENED STATUS FOR SOUTHERN POPULATION, DENIES LISTING FOR NORTHERN POPULATION


Photo: Dan. W. Gotshall
 

A petition for listing the North American green sturgeon (Acipenser medirostris) under the federal Endangered Species Act was submitted by the Center for Biological Diversity, Environmental Protection Information Center, and WaterKeepers Northern California in June 2000. On April 6, 2005 the National Marine Fisheries Service (NMFS) proposed listing the southern population of the green sturgeon, but denied protection for spawning populations of this rare fish in the northern portion of its range, including in the Klamath River Basin. NMFS had previously denied Endangered Species Act listing for the green sturgeon in January 2003. In response to a lawsuit by the Center, EPIC, and the Oregon Natural Resources Council, a federal District Court in March 2004 ruled that the determination was arbitrary and violated the Endangered Species Act by failing to address the decline and loss of sturgeon spawning populations from a significant portion of its former range, and ordered NMFS to publish a new listing determination. A NMFS status review found that two distinct populations of green sturgeon spawn in only three river systems in California and southern Oregon. The southern population is comprised of fish in the San Francisco Bay and Delta that spawn in the Sacramento River basin, and the northern population extends from the Eel River in Humboldt County, California to the Columbia River in Washington. View the CBD press release on the court ruling.

Eight species of sturgeon occur in North America, and four species (as well as one population of the white sturgeon) are already listed as endangered or threatened. If listed, the green sturgeon would join the Shortnose sturgeon, Gulf sturgeon, Pallid sturgeon, Alabama sturgeon, and the Kootenai River population of the white sturgeon on the Endangered Species list. Sturgeon are the largest and possibly the oldest fish found in freshwater. Some white sturgeon have been estimated at 100 years old, and green sturgeon are thought to be able to reach 60-70 years of age.

photo by Daniel GotschallThe green sturgeon is a large, olive green, bony-plated, prehistoric looking fish, with a shovel-like snout and vacuum cleaner-like mouth used to siphon food from the mud. Green sturgeon can reach 7 feet in length and weigh up to 350 pounds. This large anadromous fish ranges from Alaska to Mexico in marine waters and feeds in estuaries and bays from San Francisco Bay to British Columbia. The green sturgeon spawns in fresh water in the mainstem of large rivers.

Species Reduced to Three Spawning Populations

The only remaining spawning populations are in the Sacramento and Klamath River basins in California and possibly in the Rogue River in Oregon - rivers that have been extensively dammed, diverted, and polluted. These rivers have flow regimes affected by water projects, limiting suitable spawning conditions for green sturgeon. Increasing urban and agricultural demand for water threatens the future spawning success for the entire species. Sturgeons in general are highly vulnerable to habitat alteration and over-fishing because of their specialized habitat requirements, the long time it takes them to reach breeding maturity, and their sporadic reproductive success.

The southernmost green sturgeon populations occur in California, a region experiencing dramatic declines of its anadromous fishes due to dams, water withdrawals, and habitat alteration. A number of presumed spawning populations of green sturgeon have been lost since the 1960s and 1970s - from the Eel River, South Fork Trinity River, and San Joaquin River. Severe declines of green sturgeon have been noted recently in northern rivers which may have once had spawning populations, such as the Umpqua River in Oregon and the Fraser River in Canada.

It is currently estimated that each of the three known or suspected spawning populations of green sturgeon contain only a few hundred mature females. This is cause for alarm, because with so few females of reproductive age, not only do fish have a hard time finding each other for spawning, but also maintaining minimum population sizes for genetic diversity becomes a concern.

Over-fishing Takes Its Toll

Historic over-fishing was a major cause of decline of the species. There have been some huge catches, such as the 6,000 green sturgeon taken from the Columbia River estuary during a four-day sturgeon fishing season in 1986. The large size and sluggish nature of sturgeons make them easy to net and snag. Present fisheries for green sturgeon continue to deplete a stock of large, old fish that cannot renew itself at current harvest rates. The principal fisheries for green sturgeon are in south coastal Washington and in the nearby Columbia River estuary, yet there is no evidence of sturgeon spawning in that region. These fisheries may depend on sturgeon from California that are attracted to the area for abundant food resources.

Endangered Species Act Protection Needed

A 1992 NMFS status review of the species in California made a "conservative" recommendation that the green sturgeon be regarded as a threatened species. The American Fisheries Society recently reviewed the risk of extinction for marine fish in North American waters and determined that the green sturgeon is endangered, noting an 88% decline in most of its range. The green sturgeon clearly warrants prompt listing as an endangered or threatened species under the Endangered Species Act.

graphic Andrew Rodman ©2002
March 6, 2006
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