Moving away from a scale mismatch: Spatiotemporal modelling of striped shrimp (Pandalus montagui) density in Canada’s subarctic

Abstract

Mismatches between assessment and ecological processes can increase the likelihood of resource mismanagement, lead to the misinterpretation of population dynamics, and impact decision making. Striped shrimp (Pandalus montagui) are an important part of Canada’s subarctic marine ecosystems but have little historical research or assessment focus. Off northern Canada, striped shrimp are currently assessed separately within three assessment areas, despite these areas forming an open, dynamic system with population mixing throughout. Although assessed using data from a common survey, the differing time series of available data within each area have hampered efforts to consider the dynamics of the stock as one population and create a single biomass index for the area. Consequently, there is a spatial-scale mismatch between the biological resource and the assessment and management scales. To address causes of this scale mismatch, we developed a spatiotemporal model that can accommodate inconsistent survey coverage and can be used to estimate annual biomass of fishable striped shrimp throughout the study area over the entire time series (2005–2022). Meanwhile, to address deficiencies in biological knowledge, we concomitantly explored potential environmental and ecosystem covariates (i.e., bottom temperature, bottom salinity, and predicted potential predator densities) to further scientific understanding of striped shrimp’s relationships with their ecosystem. Our results build a cohesive population-level biomass time series and found fishable striped shrimp densities were related to depth, bottom temperature, and lagged predicted redfish density.