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Investigation of Fish Predation Refugia Concepts at Hydraulic Structures

Project ID: 1134
Principal Investigator: Connie Svoboda
Research Topic: Fish Passage and Entrainment
Funded Fiscal Years: 2012
Keywords: fish refugia, predation, fish protection, hydraulic structure, fish screen

Research Question

Hydraulic structures, including fish screening facilities and pump intakes, produce regions on a river where fish habitat is not available. The concept of fish refugia for increased fish protection at screens and other structures is relatively new. Fish refugia pockets at multiple locations along the length of a screen are currently being developed as an alternative to intermediate bypass systems on long screens. Another type of refugia that should be investigated and developed is predation refugia. This type of refugia would consist of artificial escapement features for small fish along the upstream and downstream bank transition walls or at the base of the screens on the sill. Investigation is needed to determine if fish will use artificial refugia on vertical walls, if predation is minimized when cover is available, and if refugia elements can be designed to minimize debris retention.

Need and Benefit

The Bureau of Reclamation (Reclamation) has the responsibility of delivering water to its customers in an economically and environmentally sound matter. Conflicts between the needs of water users and the ecological needs of listed species can lead to reductions in water diversions at Reclamation facilities. The concept of incorporating fish predation refugia on the upstream and downstream transitions walls and at the base of hydraulic structures has been identified by biologists and engineers as a potential way to limit the exposure of small fish to stretches of river without habitat or cover. These concepts are still in the early stages of research, and benefits to fish have not been quantified. Identifying predation refugia that does not increase maintenance requirements at facilities is critical for field acceptance. Steve Thomas, Hydraulic Engineer for the National Marine Fisheries Service in Santa Rosa, California, and Dan Meier, Fish Biologist for the U.S. Fish and Wildlife Service in Stockton, California, support efforts to increase knowledge in the area of predation refugia. If this scoping proposal advances to field or laboratory testing, it is possible that in-kind services may be provided.

Contributing Partners

None

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Scoping Paper: Investigation of Fish Refugia Concepts at Hydraulic Structures (final, PDF, 550KB)
By Connie Svoboda
Report completed on August 01, 2013

This scoping paper discusses refuges for small fish at hydraulic structures. Fish screens and other structures produce regions in a river where hydraulics are altered and fish habitat may be limited. Fish refugia provide resting areas for juvenile and small-bodied fish as well as providing protected cover from predation. The concept of creating fish refugia for increased fish protection is relatively new. This concept is explored and potential research areas are identified.
Keywords: fish refugia, fish refuges, predation, fish screens

This information was last updated on December 19, 2014
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