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Piscivore diet response to a collapse in pelagic prey populations

Environmental Biology of Fishes
By: , , , and 
https://doi.org/10.1007/s10641-017-0618-x

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Abstract

Pelagic fish populations in the upper San Francisco Estuary have experienced significant declines since the turn of the century; a pattern known as the pelagic organism decline (POD). This study investigated food habits of piscivorous fishes over two consecutive fall seasons following the decline of pelagic fish prey. Specifically, this study addressed the contribution of pelagic versus benthic prey to piscivorous fish diets, including the frequency of predation on special-status pelagic species, and the spatial variability in prey consumption. The piscivore community was dominated by Striped Bass and also included small numbers of Sacramento Pikeminnow and Largemouth Bass. Overall, pelagic prey items contributed less than 10% of the diet by weight in both years, whereas pre-POD studies gleaned from the literature found contributions of 39–100%, suggesting a major switch from pelagic to benthic prey resources. Between-year variation in piscivore diets reflected differences in environmental conditions associated with variation in freshwater outflow. No special status fish species were detected in any of the piscivore stomachs examined. The consequences of this pelagic to benthic diet shift warrants further investigation to understand its ecological relevance.

Publication type Article
Publication Subtype Journal Article
Title Piscivore diet response to a collapse in pelagic prey populations
Series title Environmental Biology of Fishes
DOI 10.1007/s10641-017-0618-x
Volume 100
Issue 8
Year Published 2017
Language English
Publisher Springer
Contributing office(s) California Water Science Center
Description 12 p.
First page 947
Last page 958
Country United States
State California
Other Geospatial San Francisco Estuary
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