Models for U.S Fish Stock Assessment

A stock assessment is a statistical summary of fish population that provides past and current information about the population, and forecasts the status of the stock. The NOAA Fisheries’ Species Information System (SIS) collects data pertaining to the stock assessments that are completed throughout the U.S. The system was standardized by categorizing statistical models used in stock assessments across the U.S. The categories of the statistical models were Statistical Catch-at-Age (SCAA), Statistical Catch-at-Length (SCAL), Biomass Dynamics, Index, Virtual Population Analysis (VPA), Equilibrium, and Unknown. An analytical summary was performed on the categories of approaches used to evaluate stock assessments. It was hypothesized the size and age based models would become more frequent over time, and approaches would differ by science center. By conducting linear regressions, it was determined the frequency of size and age based models did increase with time; thus, the alternative hypothesis was supported. The frequency at which age based models are conducted have a direct positive relationship with time. The frequency at which size based models are used to assess stocks have an inverse relationship with time which neither fails to reject null hypothesis. Also, the approaches differed based on science center rejecting the null hypothesis. SCAA was overall the most frequent approach used across science centers to evaluate stock assessments. The northern regions rely heavily on SCAA and Index approaches to evaluate stocks, while the southern regions are more likely to use a variety of approaches.