Preliminary specification for stock assessment for the Pacific saury using Stock Synthesis 3

The aim of this paper is to propose the use of Stock Synthesis 3 (SS3) as a candidate age-structured model for the next generation of the Pacific saury stock assessment. At present, due to the nature of the early stages of the collaboration, the specification has been kept simple in order to set up a framework for using the available data sets. However, we will continue to improve the structure of the model by diagnosing convergence, goodness of fit, consistency of model via retrospective analysis and model predictability. In this process, uncertainties in parameters and other assumptions are also taken into account to produce a set of plausible scenarios and robustness scenarios. In addition, better spatial and temporal resolutions will be considered to account for the effects of environmental changes as well as temporal patterns of migration and fishing activities. One of the advantages of using the existing software is the ease with which results can be shared without having to check the codes (it is sufficient to look at some inputs and then at the results). SS3 also has excellent features such as the availability of diagnostic tools, simulation platforms and links to activities for Management Strategy Evaluation (MSE). Further results will be presented at the SSC-PS08 meeting in December 2021.