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Fish Predator Reduction Using Fish Traps with Bait Attraction

Project ID: 4290
Principal Investigator: Joshua Mortensen
Research Topic: Fish Passage and Entrainment
Funded Fiscal Years: 2012 and 2013
Keywords: predation, fish passage, salvage, fish trap, fish bait

Research Question

Can common odor-releasing fish baits be used in conjunction with existing fish trap designs as a new technique for removing predator fish from Reclamation facilities?

Large piscivorous fish (i.e., striped bass, pike minnow, and catfish) reside near many of Reclamation's facilities including downstream of dams and diversions and within fish collection facilities. As a result of predation, piscivores likely have significant impacts on fish survival, passage, and salvage efficiency for many native and listed fish species, including but not limited to, delta smelt (_Hypomesus transpacificus_) and anadromous salmonids (i.e., Chinook salmon [_Oncorhynchus tschawytscha_] and steelhead [_Oncorhynchus mykiss_]). This study will evaluate the effectiveness of incorporating commonly used fish baits and collection traps to remove predators from Reclamation facilities. Fish traps are a common, passive fish capture device used to collect fish for commercial and scientific purposes. Typically, localized hydraulic conditions guide fish into the trap. Once captured, trap designs make it difficult for fish to escape.

This study proposes using an existing fish trap design and common fish baits as a new technique for removing predators from Reclamation facilities. Most predators use a keen sense of smell, among other senses, to help find prey. Many types of bait on the market expose predators to smell by adding pheromones and other odor-releasing substances as the main attraction. These smelly baits could be used on a routine basis to capture and remove resident predators from areas where our facilities cause high fish concentrations. Once in the trap, the fish can easily be removed from the site and relocated. This is a practical concept that can easily be investigated without excessive testing or equipment design because the necessary equipment is already available. This is a potentially cost-effective method that can be applied to facilities Reclamation wide.

Need and Benefit

Predation is among the greatest challenges for fish passage, survival, and salvage at various Reclamation sites and facilities. Removing predators near or within man-made facilities is oftentimes challenging due to limited access, large volumes of water, flow conditions, and high density of predators. In some facilities, such as the Tracy Fish Collection Facility (TFCF), anecdotal evidence suggests that conditions, whether as a result of high densities of available prey, facility-induced disoriented prey, or preferred habitat for ambushing, has resulted in predators (e.g., striped bass) becoming residents within major facility components. Because of the optimal conditions in man-made facilities for large piscivores, the likelihood for survival and ultimately salvage of other fish species entering or passing through Reclamation facilities is greatly decreased. While the predator's demand for food is a significant drawback for fish salvage, it may be used advantageously to remove resident predators by baiting them into a fish trap using odor-releasing baits.

Contributing Partners


Research Products

Research from Phase 1 will produce a technical memorandum that summarizes observations and results from laboratory testing. These results will include the types of fish baits that were tested and their ability to attract fish into a trap. Recommendations of the importance of continuing testing in the field will also be provided. This memorandum will be submitted by September 30, 2012.

Phase 2 will provide a report which will summarize results from the field testing. Recommendations will be provided on how this new technique should be used as well as various Reclamation sites where it can be applied.

This information was last updated on April 24, 2014
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