Southern Right Whale Eubalaena australis in the Golfo San Matías (Patagonia, Argentina): evidences of recolonization

ARIAS, MAGADALENA; COSCARELLA, M. A.; CRESPO, E. A.; GONZÁLES, RAÚL

Cambridge - Virtual

Workshop; CONSERVARION MANAGEMENT PLAN FOR SW ATLANTIC RIGHT WHALE; 2021

International Whaling Commission

Since the 1980s, the distribution range of the southern right whale (Eubalaena australis) inArgentina was mostly located in the winter calving grounds around Penı´nsula Valde´ s. Afterthe international moratorium that forbade the commercial hunting, southern right whaleshave shown signs of recovery during the last few decades. Nowadays, it is thought that thespecies is experiencing a density-dependent process while expanding its distribution rangein Patagonia. From 2007 to 2016, data on right whale distribution, group composition andrelative abundance were collected in Golfo San Matı´as, Patagonia through aerial surveys.Generalized linear models with a negative binomial error distribution were used to determinethe population trend of right whales in this area. In addition, the group composition and therelative abundance of right whales among the northern Patagonian gulfs were compared.Finally, a literature review was conducted to assess the historical presence of right whalesin Golfo San Matı´as, revealing the presence of right whales in Golfo San Matı´as during andafter the commercial exploitation. During aerial surveys (2007?2016), right whales wereobserved from August to October in the area, with a peak in late August-early September.Our results suggested a geographic distribution change with a regular use of the northwestcoast of the gulf in recent years and a positive trend in the population growth rate insideGolfo San Matı´as. This area was dominated by unaccompanied whales (solitary individualsand breeding groups) as opposed to Penı´nsula Valde´s where the dominant group type wasthe mother calf pairs. Therefore, Golfo San Matı´as appears to be important for socializingand mating but not as a nursery ground. In addition, the density of whales was four timesgreater in the gulfs of Penı´nsula Valde´ s. Our findings contribute to a better understanding ofthe recovery of this species in Patagonia, Argentina and should be considered for the managementmeasures for right whales in this region.