Area usage estimation and spatiotemporal variability in distribution patterns of southern right whales, Eubalaena australis, of southern Brazil

摘要

Southern right whalesEubalaena australis (Desmoulins, 1822)migrate seasonally from high-latitude feeding grounds to coastal breeding and calving grounds at lower latitudes such as the southern coast of Brazil. Understanding how these whales are distributed along the coast is important for monitoring their postwhaling recovery and defining management strategies. In this study, we applied Kernel density estimators to aerial survey data to determine main occurrence and concentration areas of right whales in southern Brazil and investigate inter- and intra-annual distribution patterns between 2003 and 2012. Our results show considerable variation in area usage within and among years, and changes in the general distribution pattern of right whales in the last years of the study. Intra-annually, higher concentration area tended to expand from July to September and decrease in November. Some areas stood out as high-density areas for right whales: Ribanceira/Ibiraquera, Itapiruba Sul/Sol, and from Arroio to Gaivota. Some evidences also suggest preferential areas for mother-calf pairs. The higher concentration area of right whales in southern Brazil was estimated at 52,541km(2) and the occurrence area was 682.69km(2), which is the whole study area. As right whale distribution in the region is likely expanding due to this population's current recovery, our study provides essential information for management plan of the Right Whale Environmental Protection Area.