Integrating Fine-Scale Habitat Data with Onboard Observer Surveys to Inform Indices for West Coast Groundfish

California’s saltwater recreational fishery is one of the largest in the U.S.  The California Department of Fish and Wildlife conducts an onboard observer program within the Commercial Passenger Fishing Vessel fleet primarily to monitor in-season activity.  Onboard observers collect location-specific catches and effort for a subset of anglers at each fishing stop on a trip.  Data collected in the onboard observer program can also be utilized to create indices of relative abundance, which then feed into a stock assessment model.  For a number of nearshore West Coast groundfish stocks, the only index available is from a fishery-dependent catch per unit effort time series of observed recreational angler catch rates.  Traditionally, fishing data are aggregated at the port or county level.  The availability of finescale bathymetric data from the California Seafloor Mapping Project allows us to model the onboard observer data at a rocky reef-specific level.  From the seafloor mapping data, we determined areas of suitable rocky habitat and assigned fishing stops from the onboard observer program to individual rock reefs.  These areas are then used to appropriately weigh reef-specific estimates of CPUE when constructing time series of relative abundance.  We present examples for China rockfish, black rockfish, and kelp greenling.