Improving Stock Assessments for Rockfishes Using Habitat-referenced Acoustic Surveys in the Gulf of Alaska

Benefits to stock assessment and management:

This project builds on earlier work to assess rockfishes in untrawlable habitat, and will benefit stock assessments for the FSSI stocks of GOA dusky rockfish, northern rockfish, and Pacific Ocean perch in several ways. Biomass estimates can be refined by accounting for untrawlable regions in the survey area to better estimate the survey catchability coefficient (q), which largely reflects the availability of the population to the survey gear. Estimates of q for Alaska rockfishes are currently hypothesized to reflect the differential densities between trawlable and untrawlable habitats, and empirical data would improve specification of Bayesian priors on q. Methods developed here and knowledge gained through this and related studies can ultimately be used to begin time series of rockfish abundance estimates in untrawlable areas to complement traditional BT survey data. Additionally, the proposed experimental design is flexible enough that the work could easily be expanded to additional sites that could be sampled using AC survey methods to refine our proposed summer 2015 estimates.

This project was in response to the Habitat Information for Stock Assessment RFP.

7600 Sand Point Way NE, Building 4