Zeug, S.C., M. Beakes, J. Wisenfeld, M. Greenwood, L. Grimaldo, J. Hassrick, A. Collins, S. Acuña, and M. Johnston

Publication Date

15 September 2020

Publication Name

Estuaries and Coasts

Tuesday September 15, 2020

Researchers performed two field experiments with enclosures deployed in tidal freshwater habitat to quantify effects of non-native Largemouth Bass (Micropterus salmoides) density and habitat type on the survival and movement behavior of juvenile Chinook Salmon (Oncorhynchus tshawytscha). In experiment one, bass densities were doubled and quadrupled across treatment levels with a baseline value of field-observed densities. In experiment two, three habitat types (dock, submerged aquatic vegetation (SAV), and open water) were tested while bass density was held at the medium (doubled) value. Juvenile Chinook Salmon implanted with passive integrated transponders were released into the enclosures to assess their survival and movement through the treatments over multiple trials. Mark-recapture models indicated that the survival of juvenile Chinook Salmon was reduced in the medium bass density, but not the high-density treatment, when compared to the lowest density value suggesting relationships may be non-linear. The SAV treatment had a well-supported negative effect on juvenile Chinook Salmon survival relative to a dock or open water. These results suggest that restoration strategies targeting non-native SAV control could reduce predation on juvenile Chinook Salmon by Largemouth Bass.
However, piscivore density manipulation may only be effective over a narrow range of densities

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