Recruitment variability estimated by the sardine assessment model
reportposted on 19.05.2021, 08:50 by Carryn de MoorCarryn de Moor
When the Hockey-stick stock recruitment relationship was estimated during the conditioning of the Operating Model for South African sardine (de Moor 2016a, de Moor 2018), the estimated 𝜎𝜎𝑅𝑅𝑆𝑆 was close to the lower bound of the prior distribution for the west component, where (𝜎𝜎𝑅𝑅𝑆𝑆)2~𝑈𝑈(0.16,10). Mixing of the MCMC chain for 𝜎𝜎𝑅𝑅𝑆𝑆 has been slow and thus 𝜎𝜎𝑅𝑅𝑆𝑆 has been fixed at a constant during MCMC simulations, and therefore also in projections of the population dynamics during the development of multiple OMPs. However, when the Operating Model was conditioned without any stock recruitment relationship and the Hockey-stick stock recruitment relationship subsequently estimated after conditioning (de Moor 2016b), the estimated 𝜎𝜎𝑅𝑅𝑆𝑆 was much higher for both the south and west components.