Lengthening Our Stride: Evaluating the Inclusion of Length Compositions When Enhancing Data-Limited Stock Assessments

The application of stock assessments to fisheries management on the west coast of the United States has been greatly enhanced by the ongoing development of Stock Synthesis, a flexible statistical catch-at-age framework. While this framework has been enhanced to incorporate more data and parameters, recent develops have also demonstrated its use in data-limited situations. Both catch-only and catch-index only modelling exercises have proven useful in obtaining management and/or biological quantities. This work attempts to expand the catch-index applications by incorporating current year length or age compositions so as to define selectivity curves and improve biomass and status estimation. This work is applied to several west coast groundfish stocks and compared to both the full assessments and the simpler applications in order to identify the use of such data. The results aim to improve our understanding of modelling under data-constraining situations, as well as offer insight in data collection and stock assessment prioritization.