Is there spatial segregation between reproductive groups of southern right whales along the coastline of southern Brazil?

• Published in: Marine Mammal Science
• Main Authors: Renault‐Braga, Eduardo P., Groch, Karina R., Simões‐Lopes, Paulo C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Southern Right Whale
• Online Access: http://dx.doi.org/10.1111/mms.12797; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12797; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mms.12797

Abstract Santa Catarina State, in southern Brazil, is an important breeding ground for the southern right whale and it is possible to record mother‐calf pairs and unaccompanied adults that migrate to this coast to either give birth, mate, or socialize. From the geographical position of the sightings, spatial segregation was evaluated between mother‐calf pairs and unaccompanied whales. Using GAM, we analyzed 15 years of aerial survey data from 2003 to 2018. The study area (780 km 2 ) was divided into 500 × 500 m grid cells. Whale count per grid cell was modeled using a set of explanatory variables. The explanatory variables of latitude, coast distance, seabed, and maximum SST were selected for both classes. However, coast type was also selected for unaccompanied whales, while coast linearity and bathymetric slope were additionally selected for mother‐calf pairs. The response curves fitted by models indicated a certain degree of spatial segregation, by which mother‐calf pairs remained closer to the coast, where the curve peak is reached at 500 m from the coast, compared to unaccompanied whales where the curve peaked near 1,000 m from the coast. Also, unaccompanied whales more frequently appeared in the southern boundaries of the study area, at latitudes south from 28.4°S.