White sturgeon Acipenser transmontanus are the largest North American sturgeon. They live in rivers from central California to southern Alaska and migrate among them via the Pacific Ocean. In the Columbia River they historically ranged from the ocean up into Idaho, Montana, and Canada. White sturgeon can live for over 100 years, can be 20 feet long, and can weigh over 1500 pounds. Their skeleton is largely cartilage and they have thick skin and bony plates, called scutes, instead of scales. Sturgeon appeared in the fossil record 200 million years ago and have survived to the present relatively unchanged. Female sturgeons spawn at 15-20 years of age (males are about 12 years old), and can produce 300,000-4,000,000 eggs. Of these, fewer than 0.1% will survive the first year. Historically sturgeon moved freely throughout their range, but with the construction of dams movements have been severely restricted.
White sturgeon were overfished in the late 1800s and populations diminished enough to warrant restoration actions. By the mid 1900s populations recovered enough to support commercial and recreational fisheries. Construction of Columbia River Basin dams have severely restricted movements of white sturgeon and two of their principal food sources (eulachon (or Pacific smelts) and Pacific lamprey), and degraded or destroyed spawning and rearing habitat.
With the decline in anadromous salmonid runs there has been an increase in the importance of the white sturgeon fisheries. Since 1986, ODFW has been working to determine the cause of white sturgeon declines in the reservoirs and to take actions that will restore abundance and productive fisheries. Over time, project goals have changed as new information clarified potential restoration actions.
There are two primary goals of the current project.
- 1)Implement and evaluate selected measures to protect and enhance white sturgeon populations and to mitigate for effects of the hydropower system on production of white sturgeon in Columbia River impoundments downstream from McNary Dam.
- Determine the need and identify potential measures for protecting and enhancing white sturgeon populations and mitigating for the effects of the hydropower system on production of white sturgeon in the Columbia and Snake rivers upstream from McNary Dam.
To ensure the sturgeon populations remain healthy and abundant enough to allow fisheries now and into the future, we have developed ways to monitor the abundance, recruitment, and harvest rates. A Sturgeon Management Task Force, comprised of tribal and state agency fisheries managers, works on annual management plans that are designed to protect and enhance white sturgeon populations in Zone 6 (Bonneville, The Dalles, and John Day reservoirs). There is currently a sport and commercial fishery in Zone 6 allowing for a total of 6,340 fish to be harvested. This is up significantly from 1996 when the total harvest guideline was 3,200 fish.
Our studies have shown that production of juvenile white sturgeon below The Dalles Dam is much greater than in The Dalles and John Day reservoirs. Conversely, growth of subadult white sturgeon is faster in The Dalles and John Day reservoirs compared to Bonneville reservoir. By transplanting subadult sturgeon from below Bonneville Dam into The Dalles and John Day reservoirs we hope to help these reservoirs reach their full potential. In fall of 2000 we transplanted 5,842 subadult white sturgeon.
To evaluate variation in the production levels of juvenile sturgeon we conduct annual young-of-year indexing. We have index sites from Lower Granite Dam to the mouth of the Snake River, and from Priest Rapids Dam to Bonneville Dam on the Columbia River. By sampling these areas annually we can describe distribution and relative abundance of young-of-year white sturgeon in each reservoir. As more information is collected we can look for trends among years and among reservoirs.
To ensure that mitigation actions are working as expected, we periodically update the population status between Bonneville and McNary dams in the Columbia River. In the summer of 2001, we will be working in the John Day Reservoir. The last stock assessment conducted there was in 1996, and we estimated the abundance of fish 3-6 feet long to be around 24,000. Using data collected this summer, we will update the abundance of white sturgeon in this reservoir and determine if we need to modify our management approach.
The White Sturgeon Project is funded by the Bonneville Power Administration. The Columbia River Investigations project leader is Tucker Jones.
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