Spatial stock structure of northern shrimp Pandalus borealis Krøyer, 1838 (Decapoda: Caridea: Pandalidae) in Canada’s Northwest Atlantic

Abstract

Northern shrimp, Pandalus borealis Krøyer, 1838, are thought to form one biological unit, connected through larval dispersal, from Baffin Island in the north to the Grand Banks of Newfoundland and Labrador in the south. Current stock assessments suffer from misalignments in management, assessment, and biological spatial scales. To adequately manage and model stock dynamics, the spatiotemporal patterns in stock structure must be identified to the extent possible. We identified spatial patterns in density and life history traits (sex ratio and female length) using spatiotemporal modelling. Density peaked in depths near 250–300 m (along slope edges), the proportion of males declined as depth increased, and maximum female length was predicted in waters deeper than 400 m and in more northern areas. These spatial patterns were combined with updated genomic and larval dispersal patterns to illustrate underlying structure throughout the study area. We found two consistent north/south clusters through the time series, notably different from the current assessment and management areas used throughout the region. Spatial heterogeneity of northern shrimp dynamics and the resulting stock structure should be considered within northern shrimp assessment models to ensure proper model specification and appropriate management of the stock.