Whale, whale, everywhere: increasing abundance of western South Atlantic humpback whales (Megaptera novaeangliae) in their wintering grounds
MetadataShow full item record
The western South Atlantic (WSA) humpback whale population inhabits the coast of Brazil during the breeding and calving season in winter and spring. This population was depleted to near extinction by whaling in the mid-twentieth century. Despite recent signs of recovery, increasing coastal and offshore development pose potential threats to these animals. Therefore, continuous monitoring is needed to assess population status and support conservation strategies. The aim of this work was to present ship-based line-transect estimates of abundance for humpback whales in their WSA breeding ground and to investigate potential changes in population size. Two cruises surveyed the coast of Brazil during August-September in 2008 and 2012. The area surveyed in 2008 corresponded to the currently recognized population breeding area; effort in 2012 was limited due to unfavorable weather conditions. WSA humpback whale population size in 2008 was estimated at 16,410 (CV = 0.228, 95% CI = 10,563–25,495) animals. In order to compare abundance between 2008 and 2012, estimates for the area between Salvador and Cabo Frio, which were consistently covered in the two years, were computed at 15,332 (CV = 0.243, 95% CI = 9,595–24,500) and 19,429 (CV = 0.101, 95% CI = 15,958–23,654) whales, respectively. The difference in the two estimates represents an increase of 26.7% in whale numbers in a 4-year period. The estimated abundance for 2008 is considered the most robust for the WSA humpback whale population because the ship survey conducted in that year minimized bias from various sources. Results presented here indicate that in 2008, the WSA humpback whale population was at least around 60% of its estimated pre-modern whaling abundance and that it may recover to its pre-exploitation size sooner than previously estimated.
Bortolotto , G A , Danilewicz , D , Andriolo , A , Secchi , E R & Zerbini , A N 2016 , ' Whale, whale, everywhere: increasing abundance of western South Atlantic humpback whales ( Megaptera novaeangliae ) in their wintering grounds ' PLoS One , vol 11 , no. 10 , e0164596 . DOI: 10.1371/journal.pone.0164596
Copyright: © 2016 Bortolotto et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
Showing items related by title, author, creator and subject.
Changes in dive behaviour during naval sonar exposure in killer whales, long-finned pilot whales, and sperm whales. Sivle, Lise D; Kvadsheim, Petter H; Fahlman, Andreas; Lam, Frans Peter; Tyack, Peter Lloyd; Miller, Patrick (2012-10-11) - Journal articleAnthropogenic underwater sound in the environment might potentially affect the behavior of marine mammals enough to have an impact on their reproduction and survival. Diving behavior of four killer whales (Orcinus orca), ...
Two intense decades of 19th century whaling precipitated rapid decline of right whales around New Zealand and East Australia Carroll, E.L.; Jackson, J.A.; Paton, D.; Smith, T.D. (2014-04-01) - Journal articleRight whales (Eubalaena spp.) were the focus of worldwide whaling activities from the 16th to the 20th century. During the first part of the 19th century, the southern right whale (E. australis) was heavily exploited on ...
Responses of male sperm whales (Physeter macrocephalus) to killer whale sounds : implications for anti-predator strategies Cure, Charlotte; Antunes, Ricardo Nuno; Alves, Ana Catarina De Carvalho; Visser, Fleur; Kvadsheim, Petter H.; Miller, Patrick (2013-04-02) - Journal articleInteractions between individuals of different cetacean species are often observed in the wild. Killer whales (Orcinus orca) can be potential predators of many other cetaceans, and the interception of their vocalizations ...