## Largemouth Bass Research Largemouth bass are native to the Mississippi drainage but wer e to California in the late 1890s as a game fish and probably expa n the Delta in the early 1900s. While they have been residing in th e at least 100 years, it is only in the last few decades that they hav extremely abundant, now supporting a renowned recreational fis h Largemouth bass are notoriously vo racious predators, but their n history in the Delta (distribut ion, habitat preferences, food habits ) reasons for their increasing popul ations have not been well docu One major hypothesis for their rise in population numbers is that weeds (such as Brazilian waterweed, Egeria densa) have also expanded in the Delta over the same time period, and might prov excellent habitat for bass. The increases in bass and aquatic weed s are part of major changes in the entire biological community shorelines of the Delta that have occurred since the mid 1980s. Our recent studies have examined the largemouth bass distribut ion, diet, association with aquat ic weeds and other environmen t variables in the Delta, as well as investigations of their movement patterns using acoustic telemetry. This work has been done b researchers in the Aquatic Ecology Section of DWRand the University of California, Davis( Dr. Andrew Sih in the Department o f Environmental Science and Policy, and Dr. Peter Klimley ’s Biotelemetry Laboratory). Resulti ng analyses will provide information seasonal movement patterns, patterns of abundance and growth with respect to abiotic and biotic conditions, and diet composit i bioenergetics for the largemouth bass population in the Delta. The results from this re search will provi de insights that manage rs assess whether largemouth bass are import ant predators for native fishes and underst and the reason for their recent expansio n Delta.
Recent Results Ferrari, M.C.O, L. Ranåker, K.L. Weinersm ith, M.J. Young, A. Sih, and J.L. Conrad. 2013. Effects of turbidity and an inva s waterweed on predation by introduced largemouth bass. Environmental Biology of Fishes. Published online March 2013: http://link.springer.com/a rticle/10.1007/s10641-013-0125-7

. Conrad, J.L., K.L. Weinersm ith, M.J. Young, D. de Carion, E. Hestir, M. Sant os, P. Crain, S. Ustin, P.B. Moyle, and A. Sih. More big bass: Understanding the role of largemouth bass as top predators in the littoral zone (PDF, 1 KB). Delta Scienc e Conference, Sacramento, CA. September 2010. Vella, M., C. Nelson, and J.L. Conrad. 2010. Patterns in largemouth bass diet comp osition in the Sacramento-San Joaqui (PDF, 1.20 MB). DWR Environmental Scientis t Workshop, Sacramento, CA. September 2010. Conrad, J.L., K.L. Weinersm ith, M. J. Young, D.de Carion, P. Crain, E. L. Hestir, M. J. Sant os, S.L. Ustin, P. B. Moyle, and 2010. Rising abundance of largemouth bass in the littoral zone ofthe Sacramento-San Joaquin De lta: the role of Egeria d (PDF, 1.40 MB). Interagency Ecological Program 2010 Workshop, California State University, Sacramento, May, 2010. Conrad, J.L. , K.L. Smith, E. Hestir, M. Santos, A. Sih, and S. Usti n. Largemouth bass abundance and diet in the Sacram e Joaquin Delta: investigating temporal and spatial variation with respect to subm erged aquatic vegetation. State of the Est u Conference, Oakland, CA, September 2009. 

### Aquatic Ecology Section http://www.water. ca.gov/aes/predators/largemouthbass.cfm

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### Aquatic Ecology Section http://www.water. ca.gov/aes/predators/largemouthbass.cfm

2 of 2 4/20/2016 4:10 PM