Quantifying the Benefits of Habitat Restoration
Carlton

A primary goal of the Central Valley Project Improvement Act (CVPIA) is to double natural production of Chinook salmon in California Central Valley streams through restoration actions that involve both non-discharge (e.g., gravel augmentation) and discharge (e.g., flow management) components.  Quantifying these benefits has been hindered by the inability traditional sampling techniques to identify juveniles emerging within restored sites and those that benefited from flow management on a river-wide scale. This project used new genetic mark-recapture and otolith reconstruction tools to explicitly test (1) the extent to which restored spawning sites produce a greater number of juveniles to the CVPIA-funded rotary screw traps than non-enhanced sites, and (2) how water operations influence the expression and survival of different outmigration strategies (fry, parr, smolts) to adulthood.  These data dovetailed with existing monitoring efforts (e.g., carcass survey and rotary screw traps) and provided important information on the success of restoration projects and guidance for flow management actions within the lower American River.  

A parental genotype database was created by genotyping all adult (carcass) samples. Each carcass was associated with either a restored or unrestored site.  Maximum likelihood methods were employed to assign or relate out migrating juvenile genotypes to adult genotypes in order to determine spatially explicit recruitment patterns. Results directly link the genotype of the juveniles coupled with the meta-data of the rotary screw trap (fish size, outmigration timing) to genotype of parentst taken from the carcass surveys from both restored and unrestored sites. This analysis documented recruitment from enhanced sites and provided a recruitment metric (juveniles per female) for both restored and unrestored sites.