Southwestern Atlantic Southern Right Whales Eubalaena australis still growing but at a decelerated speed

CRESPO, ENRIQUE ALBERTO; PEDRAZA, SUSANA NOEMÍ; DANS, SILVANA LAURA; SVENDSEN, GUILLERMO MARTÍN; DEGRATI, MARIANA; COSCARELLA, MARIANO ALBERTO

MARINE MAMMAL SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 34

0824-0469

This paper reports on aerial surveys conducted to estimate the relative abundance and trend in growth of the southern right whale (Eubalaena australis) population from Península Valdés. The number of whales counted tripled from 1999 to 2016. We modelled the number of whales, the number of calves, the number of Solitary Individuals and the number of individuals in Breeding Groups using as predictive variables the Year, Julian day and Julian day2 by means of generalized linear models. The rate of increase decreased from near 7% in 2007 to a 0.06% and 2.30% for total number of whales and number of calves, respectively for 2016. Trends in the rates of increase for total number of whales and number of calves were negative (-0.732% and -0.376%, respectively). The habitat use of the whales changed along the years, with mothers and calves using more heavily the near-shore strip, resulting in a decreasing trend for solitary individuals and breeding groups in near-shore waters. We conclude that whales are still increasing their abundance, while the rate of increase is decreasing. Differences in the rates of increase of the group types and changes in habitat use are thought to be consequence of a density dependence process.