Sacramento River Predator Diet Analysis: A Comparative Study

This study examined diets of two predatory fish species, the native Sacramento Pikeminnow (Ptychocheilus grandis) and the introduced Striped Bass (Morone saxatilis), in the Sacramento River, California, USA. Both species have been implicated in native species declines through predation, eliciting our investigation of their diets in the Sacramento River. Sampling occurred between March and November 2017, and was conducted via hook and line on a 35-km reach near Chico, California. Habitat types sampled include engineered structures (water diversions and beam bridges), rip-rapped channel edges, and natural riverbank. Stomach contents were collected via gastric lavage and later processed using visual, gravimetric, and genetic techniques. Diets of Sacramento Pikeminnow and Striped Bass were highly similar as determined through index of relative importance and PERMANOVA modeling. Water temperature was the only variable that significantly affected diet composition. Results reflect similar dietary niches for both species in the Sacramento River

Mod Waters and CERP sampling sites in the Florida Everglades.

<p>CERP models were based on three years of data pooled from all sampling sites. Mod Waters models were broken down into three, six, nine, and twelve years of data. Spatial scales used were Ecosystem (all Mod Waters sites), Regions (sites within Water Conservation Area, Shark River Slough, or Taylor slough), individual sites, and plots (not shown – 100 m2 areas within each site).</p

Overview of methods.

<p>Flow chart providing an overview of a) model creation, b) creation of datasets for prediction, and c) application of models to datasets for prediction. Note that the details for each data set differs. Details for step (a) can be found under the heading <i>Model </i><i>Creation</i> and <i>Parameterization</i> in the methods section. Details for steps (b) and (c) are available under the heading <i>Model </i><i>Application</i> in the methods section.</p