Ecology of Delta Smelt


Arguably one of the most imperiled and controversial fish species, recent record-low abundance of threatened delta smelt is responsible for dramatic reductions in freshwater allocated from the Delta and San Francisco Estuary to central and southern California.

This project is an urgent effort, mounted in conjunction with federal and state agencies, to provide basic research on the delta smelt population. An interdisciplinary team is quantifying mortality due to changes in food webs processes and exposure to pollutants for field-caught delta smelt to compare with estimates of their losses to the federal and state water export facilities in an array of population models.

Exploratory data analyses were used to synthesize existing biological information and develop conceptual models to guide the work (See link to published monograph on delta smelt ecology, below). With collaborators Dr. Swee Teh of Veterinary Medicine, Dr. Wim Kimmerer at SFSU, and Dr. James Hobbs, former graduate student and current CALFED Science Fellow at UCB, an interdisciplinary program has been implemented to assess fish growth and spawning location using otolith microstructure analyses, as well as tissue condition using various biomarkers.

This approach has been very effective at distinguishing effects of poor-feeding success from exposure to pesticide runoff for individual field-caught specimens. Information from this research is being used to develop stage-structured population models to assess multiple effects on the dynamics of the population.

We are also using this information to calibrate a recently completed individually-based population model that is integrated with a hydrodynamic particle-tracking model (with collaborators Dr. Kenny Rose, LSU, and Dr. Steven Monismith, Stanford).

The overarching goal of these efforts is to provide the state and federal Resources agencies with management and restoration options for the threatened population.