Distribution and relative abundance of large whales in a former whaling ground off eastern South America

Abstract

Ship-based sighting surveys for cetaceans were conducted in the former whaling ground off the northeastern coast of Brazil. The cruises took place in winter and spring of 1998-2001 with the objectives of investigating current distribution and abundance of cetaceans, particularly large whale species taken during whaling. In 1998 the survey were conducted between the parallels 5°30'W and 9°S and the 200 m isobath and the meridian 033°W. A total of about 3,100 nm were surveyed between 1998 and 2001 Surveys were conducted using line transect methods from about 5-10°S, and from the coast to 33°W. A total of 151 sightings (203 individuals) of large whales were recorded on effort. The Antarctic minke whale - Balaenoptera bonaerensis (Burmeister, 1867) was the most frequently sighted species (97 groups/132 individuals; Sighting Rate [SR] = 0.031 groups/nm), being recorded only in offshore waters. Density gradually increased from August to October. Minke whales were distributed throughout the area, both to the north and the south of former whaling ground. Sighting data indicate this is the most abundant species, particularly in the area beyond the continental shelf break. Breeding behavior was observed for Antarctic minke whales, but few groups containing calves were recorded (4.3% of the groups sighted on effort). Three other large whale species were recorded in low numbers: the Bryde's whale - Balaenoptera edeni (Anderson, 1879)¹; the sei whale, B. borealis (Lesson, 1828), and the sperm, Physeter macrocephalus (Linnaeus, 1758). Sei, Bryde and sperm whales were regularly caught during whaling operations, but are rare in the area, suggesting they were depleted by whaling and have yet to recover to their pre-explotation abundance. In contrast, minke whales are abundant in this area, suggesting that either they were not substantially depleted, or that they have recovered rapidly. Blue whale, Balaenoptera musculus (Linnaeus, 1758), and fin whale, B. physalus (Linnaeus, 1758), not recorded on our surveys, have always been extremely rare in the area

Cetacean records along a coastal-offshore gradient in the Vitória-Trindade Chain, western South Atlantic Ocean

“…Thousands of Antarctic minke whales were hunted off the northeastern coast of Brazil and the Antarctic during the last century (Horwood, 1990), but this species was the most frequently sighted during a recent 4-year survey in offshore waters of the former whaling ground off Costinha in the State of Paraíba -from 6° to 8° S, and 33° to 35° W (Andriolo et al, 2010b). Significant numbers of Antarctic minke whales are found in waters deeper than 200 m from 5° to 12° S (Andriolo et al, 2010b). Still, little information exists about the southern and northern limits of the breeding ground of Antarctic minke whales off Brazil.…”

“…In fact, a closer look at the IUCN red list data base indicates that more than half of those listed as "Data Deficient" live primarily in pelagic environments and may never approach the coast (Jefferson et al, 2008;IUCN, 2012). In Brazil, search efforts for cetaceans in pelagic waters are rare (e.g., Andriolo et al, 2010b).…”

From the southern right whale hunting decline to the humpback whaling expansion: a review of whale catch records in the tropical western South Atlantic Ocean

“…, Andriolo et al. ,b), and today the two species are the best studied baleen whales (Mysticeti) in Brazilian waters.…”

Photo-id catalog points to some degree of Bryde’s whales (Balaenoptera edeni) site fidelity to Cabo Frio region, southeastern Brazil

“…In Brazil, Bryde's whale is commonly found in coastal waters (Zerbini et al, 1997), but there are also reports from oceanic areas (Andriolo et al, 2010). Available information about the species in Brazil is scarce, and reports mainly focus on occurrence, behavior and habitat use along the south-eastern coast (Siciliano et al, 2004;Carneiro, 2005;Gonçalves & Andriolo, 2006).…”