Humpback whales (Megaptera novaeangliae) are a cosmopolitan species and perform long annual migrations between low-latitude breeding areas and high-latitude feeding areas. Their breeding populations appear to be spatially and genetically segregated due to long-term, maternally inherited fidelity to natal breeding areas. In the Southern Hemisphere, some humpback whale breeding populations mix in Southern Ocean waters in summer, but very little movement between Pacific and Atlantic waters has been identified to date, suggesting these waters constituted an oceanic boundary between genetically distinct populations. Here, we present new evidence of summer co-occurrence in the West Antarctic Peninsula feeding area of two recovering humpback whale breeding populations from the Atlantic (Brazil) and Pacific (Central and South America). As humpback whale populations recover, observations like this point to the need to revise our perceptions of boundaries between stocks, particularly on high latitude feeding grounds. We suggest that this “Southern Ocean Exchange” may become more frequent as populations recover from commercial whaling and climate change modifies environmental dynamics and humpback whale prey availability.
Baleias-jubarte (Megaptera novaeangliae) migram anualmente desde as águas frias dos polos, onde alimentam-se de krill e pequenos peixes, em direção a regiões tropicais e subtropicais em busca de ambientes favoráveis para reprodução e cria de filhotes. Ainda pouco conhecidos são os casos de baleias-jubarte alimentando-se em áreas de reprodução. Nesse trabalho relatamos as primeiras observações em campo de uma baleia juvenil – yearling, em provável comportamento de forrageamento buscando por prováveis crustáceos ou cefalópodes em curtos mergulhos fundos. São relatadas outras observações semelhantes nas quais das baleias pareciam aproximar-se de redes de emalhe, provavelmente atraídas por peixes ali enredados e disponíveis. Considera-se que em alguns desses casos a aproximação das baleias em direção às redes tenha causado emalhamentos, que pelo menos em um caso o exemplar libertou-se das redes. Em outros casos as redes podem ter causados ferimentos e lesões nas baleias-jubarte. Recomenda-se um acompanhamento dessas interações pela costa brasileira a longo prazo para uma melhor avaliação dessas interações.Palavras-chave: Baleia-jubarte; Enredamento; Forrageamento; Brasil.ABSTRACTHumpback whales (Megaptera novaeangliae) migrate annually from the cold waters of the poles, where they feed on krill, towards subtropical and tropical regions in search of favorable environments for breeding and calving. Cases of humpback whales feeding on breeding grounds are still poorly known in the world. This study reports field observations of a juvenile whale - yearling, in Brazilian waters, with evidence of foraging behavior, in search of prey that seemed to be prawn or squid, during short dives. In addition, other similar observations are reported in southeastern Brazil in which the whales showed interest and approach gillnets, probably attracted by entangled fish. In some of these cases, it is considered that whale approaching towards the nets has caused entanglements, and in at least one case the specimen freed itself from nets. In other cases, nets may have caused humpback whale injuries. A follow-up of these interactions throughout the Brazilian coast is recommendedfor a better evaluation of these interactions with fishing nets, since they may represent a new form of behavior of these whales in their migratory period.
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