Grym: A new open-source implementation of the generalised yield model for flexible stock assessments

Here, we present the Grym package (Wotherspoon and Maschette, 2020). Designed to work within R (R Core Team, 2020), the Grym was built with the aim to provide a toolbox of functions that replicate the existing core functionality of the GYM software (compiled version 501E; Constable, 2004). By combining different functions, the effects of different decisions, for example varying recruitment relationships, can be tested. The Grym can be used as the underlying package
for a range of stock assessment and management strategy evaluation applications to facilitate assessments run by either non-specialist programmers or assessment scientists.