Synthesizing the spatial functionality of contemporary stock assessment software to identify future needs for next generation assessment platforms

Marine fishes are heterogeneously distributed across their ranges according to population dynamics governed by complex spatiotemporal relationships between ontogenetic habitat usage, species interactions, environmental variability, and harvest patterns. However, few stock assessments incorporate spatial population structure in the determination of population status and sustainable catch limits. A small number of generalized stock assessment software platforms are utilized worldwide to assess a large number of marine fish populations. Although each platform relies on similar underlying population dynamics, the spatial capabilities and functionality often differ among them. We catalogue spatial dynamics and capabilities across stock assessment platforms to leverage collective experiences and identify future needs for next generation assessment software packages. Despite commonalities across platforms (e.g., most models allow for a single population with spatial heterogeneity, apportionment of recruitment, and age-varying connectivity), no single platform is flexible enough to address the full breadth of spatial dynamics observed for managed marine fish species. Our review clarifies spatial assessment design and modeling ‘good practices’, while emphasizing the need for more generalizable and modular next generation assessment platforms that can account for the spatiotemporal complexity of marine resources (such as natal homing and spawning migrations, ontogenetic movement patterns, metapopulation structure, and complex fleet dynamics). Generalized, spatially-integrated assessment platforms will be key decision-tools to account for spatiotemporal species and fishery interactions, particularly as managers attempt to address climate change and implement ecosystem-based fisheries management.