Zebra and Quagga Mussels: Fish Predation on Quagga Mussels
Project ID: 9508
Principal Investigator: Cathy Karp
Research Topic: Ecosystem Needs
Priority Area Assignments: 2010 (Zebra and Quagga Mussels), 2011 (Zebra and Quagga Mussels), 2012 (Zebra and Quagga Mussels), 2013 (Zebra and Quagga Mussels)
Funded Fiscal Years: 2010, 2011, 2012 and 2013
Quagga mussels, Dreissena bugensis, from Eurasia are widespread in the Colorado River drainage and associated waterworks, and are impacting state and federal water delivery operations. One potential mussel suppression agent is predation by redear sunfish, Lepomis microlophus. In aquaria experiments, 85.7 percent of juvenile and adult redear sunfish, Lepomis microlophus, and bluegill, L. macrochirus, were found to consume quagga mussels. Predated mussels were crushed and shell material was regurgitated and defecated. Mean mussel size consumed was positively correlated with fish size (r=0.7, P=0.000). In 21 field enclosure experiments, redear sunfish significantly reduced areal mussel density (P = 0.0193, Wilcoxon Rank Sum Test) by as much as 25.3 percent. However, this decrease was not observed in 6 of 13 fish enclosures which suggests that redear sunfish may consume other prey if available. Mussel density did not decline in enclosures without fish (<1 percent) and new mussel settlement was minimal. These experiments suggest that redear sunfish, and possibly other fish species, may help to control but not eliminate quagga mussel in areas where the two species co-occur.
Fish and Wildlife Service, Department of the Interior
Lower Colorado Regional Office, Lower Colorado Region
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.
Summary of Laboratory and Field Experiments to Evaluate Predation of Quagga Mussel by Redear Sunfish and Bluegill (final, PDF,
By Cathy Karp
Research Product completed on September 23, 2014
This information was last updated on April 19, 2015
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