COS 3-1 - Resource selection by ringed seals (Pusa hispida) in the Beaufort and Chukchi Seas

Background/Question/Methods

Ringed seals (Pusa hispida) are an ice-obligate species that is both abundant and widely distributed throughout the Arctic. They are the primary prey resource for polar bears (Ursus maritimus) and hold significant cultural and subsistence value for Indigenous communities. Anticipated changes in sea ice dynamics associated with climate change were viewed as a significant threat for ringed seals, and consequently led to their listing as “threatened” under the U.S. Endangered Species Act. As such, the National Marine Fisheries Service is legally required to designate critical habitat, but representatives of Indigenous subsistence communities do not agree with the current description of the critical habitat. Identification of critical habitat can rely on several methods. Resource selection functions are widely used methods that define habitat use at a population level. In many cases, it is useful to consider animal movements when defining habitat use, taking advantage of satellite telemetry data to improve our understanding of the relative importance of different habitat types. To estimate ringed seal habitat use we integrated telemetry data from satellite tagged ringed seals within a mixed effects resource selection framework. Our approach considers satellite telemetry measurement error and includes static and dynamic environmental variables.

Results/Conclusions

Our use of a mixed effects approach provides seasonal estimates of ringed seal habitat use probabilities in the Beaufort and Chukchi Seas, while also reflecting differences in migratory patterns between individuals. We found that ringed seals have a high probability of selecting near shore habitat in summer, while distance to the ice edge was an important variable in fall. In winter and spring ringed seals have a higher probability of selecting areas of high ice concentrations. By predicting important environmental variables for ringed seals and quantifying the relative importance of habitat, we thereby offer insights into which habitats may be ‘critical’. As climate changes, potentially changing the accessibility of important subsistence species such as ringed seals to Indigenous hunters, it is important that we better understand current habitat use to predict future changes.