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Stranding Surveys

Steelhead ( Oncorhynchus mykiss ) and Chinook Salmon ( Oncorhynchus tshawytscha ) stranding surveys have been conducted on the Lower American River (LAR) for the years 2016 – 2024. Reclamation’s mission is to manage, develop and protect water and related resources in an environmentally and economically sound manner in the interest of the American people. In the National Marine Fisheries Service (NMFS) most recent biological opinion (2009), the presence of dams was identified as the most influential stressor to steelhead on the American River because it blocks passage to historic spawning and rearing habitat. Thus, Reclamation is required to monitor the effects of flow regulation by dams on the steelhead life stages present in the river system. Congruently, Reclamation has committed to significant restoration actions including salmonid spawning and rearing habitat rehabilitation on the Lower American River, which also require accurate and robust monitoring. These surveys support the mission and monitoring requirements of Reclamation by collecting the stranding data required to effectively conduct analyses of the effects of regulating Folsom and Nimbus dams on this federally listed species’ critical life stage development and support operational decision making.

Stranding surveys typically occur when: (1) there is a flow reduction of more than 1000 cfs, when the initial flow is greater than 2000 cfs or (2) there is a flow reduction of 250 cfs if the final flow will be below 1000 cfs. The low flow thresholds for stranding surveys are based on water's edge data collected by CFS during a flow reduction in January 2014; results from this field study indicate that substantial dewatering of the channel occurred at flows below 800 cfs and substantial redd dewatering occurred below 700 cfs (CFS 2014). If an isolated pool containing isolated juvenile salmonids is observed, the pool will be surveyed using a beach seine or dip net depending on vegetation and accessibility.

Cramer Fish Sciences typically uses a 50-foot wide by 4-to 5-foot tall beach seine with 1/8-inch knotless nylon diamond mesh for beach seine sampling. However, a smaller width and/or mesh size (1/16 inch) or dip nets may be used depending on fish and stranding pool size. Large cobbles and/or woody debris may be removed from the pool to eliminate risk of fish injury or damage to seine prior to seine haul. The seine is stretched out moving in the upstream direction until it is the full width and parallel to shore and then it is pulled by the team into the shore at a walking pace. The team works together to keep lead line down while bringing it into shore and ensuring that the floats stay at the water surface. If any rocks, sticks, or other objects are caught in the seine, they are removed to avoid crushing fish and damage to the seine. After debris has been removed, fish are concentrated into a small pocket in the seine and removed either by hand or with a net. If an isolated pool is too small or too vegetated to pull a seine, dipnets may be used for fish rescues. Fish captured from each seine haul or dipnet are held in five-gallon buckets containing fresh water and an aerator or live-cars secured in the body of water being seined. No more than 25 fish are placed into any one bucket, and a live car is used if water or air temperatures are greater than 18°C. Buckets or live cars are placed in the shade or under a canopy if no natural shade is available. Water quality (temperature and DO) of recovery buckets is monitored frequently and water changed if needed, particularly if air temperatures are high. Captured fish are identified and counted separately for each stranding pool. All captured fish are acclimated to main channel river temperatures before releasing into the main channel

References

Cramer Fish Sciences. 2014. Assessment of Lower American River Chinook Salmon Redd Dewatering During a Stepped Flow Reduction. Prepared for Sacramento Water Forum. 20 January 2014. 13pp.