DWRpredator09

Tagging studies on Feather River Fish Hatchery (FRFH) of salmonid smolts have revealed that they suffer high mortality while emigrating through the lower Feather River (DWR, unpublished). Between 2009 and 2013, acoustic tracking studies on FRFH steelhead smolts estimate an average apparent survival of 40% from release to the mouth of the Feather River. Preliminary acoustic data for spring-run Chinook demonstrate perhaps a more substantial impact—as few as 16% successfully emigrating out of the Feather River.

Predation by piscivorous fishes has been shown to be a substantial source of juvenile salmon mortality in other watersheds (Rieman et al. 1991; Beamesderfer et al. 1996; Kreuger et al. 2011). Similarly, we suspect that predation is a major source of mortality for hatchery smolts in the Feather River. In order to evaluate the impact of piscivorous fish on emigrating juvenile salmonids, we are conducting a multi-year predation study on the lower Feather River.

In addition to resident piscivorous fishes, such as Sacramento pikeminnow, several Micropterus spp., and channel catfish, the Feather River also has a seasonally abundant population of striped bass. Our specific study objectives include the following: (1) estimate the abundance and relative distribution of striped bass and resident piscivores in the lower Feather River during the hatchery smolt emigration period, (2) quantify predator diets, and (3) use models to estimate the reach specific and total loss of smolts due to fish predation, and (4) compare the results to patterns in estimated reach mortality of smolts.