Bayesian surplus production models for blue sharks using the legacy BSP software.

The 2015 blue sharks stock assessment included Bayesian surplus production models conducted with an old software called BSP that used the Sampling-Importance-Resampling algorithm rather than MCMC for numerical integration, along with some JAGS code that was similar to the JABBA R package that is currently used. The legacy BSP software and the old JAGS code were used with the new catch and CPUE data, but the same settings as were used for the 2015 assessment to verify that the choice of software does not influence the assessment results. The BSP software has some features that are not available in JABBA and have been used for blue sharks, such as the ability to estimate catches in the early years of the fishery from effort, and then use catches for the rest of the years. Conversely, BSP does not have JABBA’s ability to model catches as uncertain, and JABBA provides many useful diagnostics. Because the differences in software are minor and JABBA is more convenient and reproducible, JABBA should be the preferred Bayesian state-space production models for future assessments.