What do humpback whales Megaptera novaeangliae (Cetartiodactyla: Balaenopteridae) pairs do after tagging?

ZOOLOGIA 31 (2): 105–113, April, 2014 http://dx.doi.org/10.1590/S1984-46702014000200001 What do humpback whales Megaptera novaeangliae (Cetartiodactyla: Balaenopteridae) pairs do after tagging? Artur Andriolo1,3,6, Alexandre N. Zerbini2,3, Sergio Moreira3,4, José L. Pizzorno3, Daniel Danilewicz3,5, Ygor G. Maia3, Natália Mamede1,3, Franciele R. de Castro1,3 & Phillip Clapham2 1 Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora. Rua José Lourenço Kelmer, São Pedro, 36036-900 Juiz de Fora, MG, Brazil. 2 National Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA Fisheries. 7600 Sand Point Way NE, Seattle, WA, 98115, USA. 3 Instituto Aqualie. Avenida Dr. Paulo Japiassu Coelho 714, Sala 206, Cascatinha, 36033-310 Juiz de Fora, MG, Brazil. 4 Laboratório de Bioacústica e Ecologia de Cetáceos, Departamento de Ciências Ambientais, Instituto de Florestas, Universidade Federal Rural do Rio de Janeiro. Rodovia BR 465, km 7, 23890-000 Seropédica, RJ, Brazil. 5 Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz. Rodovia Ilhéus, Itabuna, km 16, 45662-900 Ilhéus, BA, Brazil. 6 Corresponding author. E-mail: ABSTRACT. The social structure of humpback whales in their tropical wintering grounds is very fluid. To date, no information has been published for cases in which two whales were both satellite-tagged while in association. Here, we report the movements of four humpback whale pairs tagged together off the coast of Brazil. Fieldwork and satellite tagging of humpback whales was conducted between 2003 and 2008 along the eastern coast of Brazil, between 20°S and 8°S. Movement was monitored while whales were still in their breeding ground. A switching state space model was applied to the filtered data of each humpback whale to standardize telemetry data and allow direct comparison of each individual track. GIS was used to plot model-predicted locations and to visually compare animal movements. The results confirm the short-lived nature of associations between breeding humpback whales, and shows that individuals differ widely in their movements. KEY WORDS. Cetacean; large whale; satellite telemetry; social behavior; SSSM. Humpback whales, Megaptera novaeangliae (Borowski, 1781), occur in all major oceans of the world. They are one of the most well studied large whale species, but much remains unknown about their behavioral ecology. In the Southern Hemisphere the species typically migrates from summer feeding grounds in the Antarctic to mating and calving grounds in tropical and subtropical coastal waters (D AW B I N 1956, CHITTLEBOROUGH 1965, MACKINTOSH 1965, ZERBINI et al. 2006, 2011). Humpbacks move through ocean waters during migration (e.g., ZERBINI et al. 2006), or during residency in feeding areas (e,g., DALLA ROSA et al. 2008). The International Whaling Commission (IWC) afforded Humpback whales virtually complete protection in the mid 1960s, and currently recognizes seven humpback whale breeding grounds in the Southern Hemisphere with corresponding feeding areas in high-latitude Antarctic waters (IWC 1998, 2005). Breeding Stock ‘A’ (BSA) corresponds to whales wintering off Brazil. In this region, the species typically occur from the northern portion of the South America (~5°S) to Cabo Frio area (~23°S) in the state of Rio de Janeiro (ANDRIOLO et al. 2010). Occasional records have been observed along the South American conti- nent and near oceanic islands (PINEDO 1985, LODI 1994, SICILIANO 1997, PIZZORNO et al. 1998), but it is not yet clear whether these regions correspond to the regular range of the species. An aerial survey conducted in 2005 constituted the first systematic effort to confirm that the southern limit of the breeding ground of Humpback whales on the continental shelf corresponded to the coast of Rio de Janeiro state (~23°S) (ANDRIOLO et al. 2010). Results from this study were further supported by satellite telemetry (ZERBINI et al. 2006). The Abrolhos Bank (16°40’ to 19°30’S) corresponds to the main breeding habitat of the species in the western South Atlantic Ocean (SICILIANO 1997, MARTINS et al. 2001, MORETE et al. 2003, ANDRIOLO et al. 2006, 2010), with some individuals showing relatively high site-fidelity to this region (WEDEKIN et al. 2010). Humpback whales that reproduce off Brazil migrate to summer feeding grounds to the west of the South Scotia Sea, near the South Georgia and the South Sandwich Islands (ZERBINI et al. 2006, 2011, STEVICK et al. 2006, ENGEL & MARTIN 2009). Animals that overwinter at the Abrolhos Bank may occasionally feed opportunistically in the waters of the western South Atlantic (DANILEWICZ et al. 2009, ALVES et al. 2009). 2014 Sociedade Brasileira de Zoologia | www.sbzoologia.org.br | www.scielo.br/zool All content of the journal, except where identified, is licensed under a Creative Commons attribution-type BY-NC. 106 A. Andriolo et al. The social structure of humpback whales in tropical waters is very fluid (HERMAN & ANTINOJA 1977, MOBLEY & HERMAN 1985, MATTILA et al. 1989). With the exception of mothers and calves, long-term associations are relatively uncommon. The groups are usually small, but lager groups are formed in association with aggressive intrasexual competition among males (TYACK & WHITEHEAD 1982, BAKES & HERMAN 1984, CLAPHAM et al. 1992). Observations of individuals in breeding ground suggest that humpbacks are not territorial (TYACK 1981, CLAPHAM 2000). Stable associations between paired whales have been noted (CLAPHAM 2000), even among larger groups in feeding grounds (PERRY et al. 1990). Humpback whales appear to be polygynous, with similarities to a lek mating system. CLAPHAM (1996) has proposed the category of ‘floating lek’ for this species. Genetic analysis of paternity has shown that females mate with multiple males, at least from one year to the next (CLAPHAM & PALSBOLL 1997). CYPRIANO-SOUZA et al. (2010) found that individuals distributed along the Brazilian coast belong to a single population, without evidence of substructure (spatial or temporal differentiation). Satellite tracking is an important tool to study the behavior and movements of marine mammals (e.g., JOUVENTIN & WEIMERSKIRCH 1990, POLOVINA et al. 2004) and has been applied to humpback whales, providing information on the habitat use, movements and migrations of individual whales (MATE et al. 1998, ZERBINI et al. 2006, 2011, DALLA-ROSA et al. 2008, MATE & BEST 2008). To date, however, there is no published information on the fate of individuals that were both satellite tagged while in association. Here, we report the movements of four pairs of humpback whales tagged together off the coast of Brazil. MATERIAL AND METHODS The breeding ground for humpback whales in this population was defined as the area within the continental shelf (depth <200 m) along the Brazilian coast between 5°S and 23°S (ANDRIOLO et al. 2010). Fieldwork and satellite tagging of humpbac (...truncated)