Circumpolar frontal systems as potential feeding grounds of Southern Right whales

Abstract

All subpopulations of Southern Right whales (SRWs) have been subject of intense commercial whaling during the 18th, 19th and 20th centuries. Although the abundance and population status of some subpopulations are improving, their recovery could be compromised if inadequate advice are given rooted in poor data on basic aspects of their ecology, such as the location of feeding grounds. In this study, we combine historical whaling data with key environmental features known to be important for Balaenids to predict the offshore distribution of SRWs throughout the Southern Hemisphere using monthly Ensemble Distribution Models. We found that the location of potential feeding grounds of SRWs changes from mid-latitude shelf and oceanic waters in September towards higher latitude waters in December, a situation that holds throughout the summer. In March and April, suitable feeding grounds reach their minimum geographic coverage, being mostly restricted to areas near calving grounds. We also provide evidence that highly suitable areas of SRWs overlap with the Subtropical Frontal Zone and the Polar Front, so these frontal systems stand as important potential feeding grounds for SRWs from late spring to early fall at circumpolar scale. Improved identification of offshore feeding areas of SRWs will require more efforts to directly observe vast areas of the open ocean and to track individuals from calving to feeding grounds.