The Longfin Smelt (Spirinchus thaleichthys) is a native forage fish, characteristic of the natural biological community of the San Francisco Estuary (SFE). This study will examine variation and interactions among hatch dates, instantaneous and total growth rates, habitat use, and timing of transitions among habitats with different salinities, and variation among years with very
different climate and freshwater outflow conditions. This information is crucial for managing freshwater flows and can be used to evaluate the effects of tidal wetland restoration in the San Francisco Estuary.
Regents of the University of California, Davis
The project objectives are:
1. Develop and refine tools using otoliths (ear bones) to retrospectively assess age, hatch dates, back-calculated size-at-age, growth rates, and habitat use (salinity) patterns including the timings of transitions among habitats for Longfin Smelt.
2. Use the otolith tools, specifically calibrated for Longfin Smelt, to describe the general biology (hatch dates, growth rates, ontogenetic changes) and habitat/salinity use patterns (range and movement patterns) of wild Longfin Smelt, and examine optimal habitat/salinity conditions that maximize growth (i.e. survival) throughout their larval and juvenile development.
3. Determine how inter-annual variability in climate (precipitation/flow) alters habitat/salinity use patterns and demographic/vital rates (hatch date, growth rate) of wild Longfin Smelt populations using archived samples that span 20 years of variable climate regimes.
Research/Planning (including Science)
Project Benefits a Disadvantaged Community (or SDAC):