Using environmental and non-targeted data for the validation of a fishery-independent survey for Northern Shrimp (Pandalus borealis)

Fisheries management relies on accurate population estimates, often sourced from fishery-independent surveys. Many surveys are spatially constrained due to logistical and financial challenges. Analysts therefore have to assume that localized sampling is representative of the entire population. The survey for northern shrimp in Nova Scotia, Canada, is one such survey, where only core areas are surveyed annually. Using the shrimp data collected from the snow crab survey, we develop an index utilizing a species distribution model and compare its trend to the shrimp stock assessment outputs that utilizes data from the shrimp survey. Results show that the shrimp data from the snow crab survey trends with the shrimp stock assessment and that the majority of shrimp are in these core areas which are representative of the overall population abundance. We highlight how this focus on core areas, while accurate for management, misses an apparent range contraction related to changes in water temperatures. Our work introduces methods utilizing non-targeted data to verify other surveys while providing external validation for the assessment of a commercially important stock.