Development of a productivity-susceptibility analysis and its application to Alaska groundfish stocks

Productivity-susceptibility analysis (PSA), which evaluates vulnerability to overfishing based upon a stock’s biological productivity and susceptibility to the fishery, can be used to classify stocks within a fishery management plan (FMP), assist in the creation of stock complexes, and inform precautionary control rules.  In the U.S., the National Marine Fisheries Service (NMFS) has developed a PSA to evaluate the vulnerability of data-poor stocks. Evaluation criteria of productivity attributes were developed to be consistent with published relationships between quantities such as maximum size and age, growth rate, and natural mortality.  Additionally, the NMFS approach includes a data quality score that describes the strength of information used to determine vulnerability.  Productivity scores for stocks in Alaska FMPs varied widely, whereas susceptibility scores were less variable possibly because inclusion in an FMP in itself implies a conservation concern. No clear demarcation was observed between high and low vulnerability stocks. Several non-target stocks had vulnerability scores equal to or greater than those of target stocks, and determining vulnerability of data-rich target stocks provided a useful means for evaluating the relative vulnerability of data-poor stocks.  The vulnerability and data quality scores have provided valuable information regarding the management of Alaska groundfish.