Humpback whales distribution in a breeding area

  • Guilherme A. Bortolotto de Oliveira (Speaker)

Activity: Talk or presentation typesPresentation


The western South Atlantic humpback whale population was severely depleted by commercial whaling in the late 19th and 20th centuries, and today inhabits a human-impacted environment in its wintering grounds off the Brazilian coast.
We identified distribution patterns related to environmental features and provide new estimates of population size, which can inform future management actions. Spatial models were fitted to line transect data and to satellite telemetry data. Line transect surveys were conducted on-board research cruises in 2008 and 2012, and satellite tracking tags were deployed from 2003 to 2012. Habitat use and abundance of humpback whales wintering on the Brazilian continental shelf were investigated. Potential explanatory variables were year, depth, seabed slope, sea-surface temperature (SST), northing and easting, current speed, wind speed, distance to the coastline and to the continental shelf break, and shelter (a combination of wind speed and SST categories).
Model-based abundance estimates were 14,264 whales (CV = 0.084) for 2008 and 20,389 (CV = 0.071) for 2012. Environmental variables explained well the variation in whale distribution; higher concentration of animals was found in the Abrolhos Bank region, using both datasets and modelling methods. Estimated distribution patterns presented here can be used to mitigate potential human-related impacts, such as supporting protection in the population’s core habitat near the Abrolhos Archipelago.
Period26 Jul 2018
Held atScottish Oceans Institute