Newswise — Responding to recommendations to increase protection for the green sturgeon in coastal waters, the Oregon Fish and Wildlife Commission recently voted to lower retention-size limits for commercial fisheries that harvest this species, an important step to ensuring a future for this living relic. The Washington Commission directed their staff to examine ways to provide additional protection for green sturgeon.
Specifically, the Oregon commission voted to reduce the commercial size limit for green sturgeon from 5 feet, 6 inches to 5 feet—a move that will protect most adult male and female sturgeons and ensure that the maximum number of fish reaching maturity continue to spawn. Green sturgeon are capable of spawning numerous times throughout their lifespan, which may exceed 60 years. "We applaud the Oregon and Washington Commissions for taking these progressive steps towards protecting the green sturgeon, a resource that represents a living link with our planet's ancient life," said WCS researcher Dan Erickson, one of the leading experts on the species.
According to the research on the green sturgeon by the New York-based Wildlife Conservation Society (WCS), the larger 5 feet, 6 inch-size limit for commercial fisheries protects most female adult fish, but leaves up to 47 percent of the smaller-sized adult males susceptible to harvest. Reducing the size limit to 5 feet ensures that the most of the adult males and the genetic diversity they represent will return to their home rivers to spawn. The decision also brings commercial limits into consistency with sports fishing size limits in Oregon and Washington, already set at 5-feet even.
Although the two remaining populations of green sturgeon use different river systems for reproduction (the northern spawns in the Rogue River in Oregon and the Klamath River in California, and the southern uses the Sacramento river system), they frequent the same coastal waters, an important conservation consideration for the entire species of fish.
While commercial demand for the green sturgeon is currently low, a number of factors have changed during the past few decades regarding the survival of the species. Factors such as loss of suitable habitat, decreased water quality, and an increase in predators, are casting doubt on the green sturgeon's long-term survival. Because the population status of green sturgeon is uncertain, efforts to reduce mortality on any front is a positive step towards securing the future of this species.
Besides providing data on green sturgeon maturation rates to commissions in Oregon and Washington State for management decisions, Erickson pioneered the usage of radio and satellite tags to follow the movements of individual green sturgeon within and outside of the Rogue River system to better understand the ecological needs of the species.
"Relative to most other species of sturgeons, some populations of both green and white sturgeon are considered to be the healthiest populations in the world," added Erickson. "By implementing precautionary management strategies in the face of uncertainty, we can ensure a future for these amazing fishes." Capable of growing more than seven feet long and weighing up to 350 pounds, the green sturgeon is one of 25 to 27 species of sturgeon worldwide, many of which are critically endangered. Green sturgeon are currently listed as a Species of Concern under the US Endangered Species Act, and the southern population of the species—which spawn in the Sacramento River—is now proposed to be listed as Threatened under this Act. Other species of sturgeon—such as the beluga sturgeon in the Caspian and Black Seas—have been brought the brink of extinction, largely because of the worldwide demand for their roe, commonly known as caviar. Imports of beluga caviar have recently been banned by the United States Fish and Wildlife Service. The potential shift in market pressure from sturgeon in the Caspian basin to other sturgeon populations around the world, including green sturgeon in North America, brings new urgency to efforts to protect sturgeon populations in U.S. waters from commercial overharvest.