First study of the survivors of humpback whales attacked by killer whales in the Southeast Pacific

Humpback whales bear signs of battle during violent encounters with orcas, also known as killer whales. Railstreak analysis of more than 3,000 tails or fingerings of humpback whales suggests that attacks on these underwater giants may be on the rise, according to a new study conducted in Research on endangered species.

"We set out to find out where, when and at what age humpback whales in the Southeast Pacific are attacked by killer whales," said Hector M. Guzman, marine ecologist at the Smithsonian Tropical Research Institute.

Orcas, Orcinus orca, like humans, are the predators of apices. Although they can feed on more than 20 different species of cetaceans, they generally prefer sea lions, fur seals, fish and seabirds. "Because the chances of observing Rake traces on vulnerable young whales have increased over the last 20 years, we believe that killer whale attacks against humpback whales are more common now than in the past, possibly due to the recovery of stocks whale breeding in the Southeast Pacific after the ban on hunting, "said Juan Capella, lead author and marine biologist at Whalesound Ltd. in Chile.

This extraordinary international team has studied photos of whales on shallow and warm breeding sites of the Las Perlas archipelago in Panama, on the island of Gorgona and in the Bay of Malaga in Colombia and on Salinas and Machalilla in Ecuador, as well as on cold water supply sites in the Strait of Magellan in Chile and the Gerlache Strait off the western Antarctic Peninsula. They found that 11.5% of adult whales and 19.5% of calves bore battle scars, figures similar to those reported from the North Pacific, North Atlantic, Eastern Australia, Tonga and New Caledonia. "The number of scars left by one whale" does not seem to change from one year to the next, suggesting that orcas primarily attack calves during their first migration, "Fernando Felix said. , marine biologist of the Pontifica Universidad Catolica and the Museum of the Whale (Museo de Ballenas) in Ecuador. They wear their scars for the rest of their lives. "

Because young feeding whales have more scars than young whales in breeding areas, researchers suspect killer whales prefer to attack young whales. Healed whales that were attacked by killer whales while calves arrived in the Magellan feeding areas with a higher number of calves than unhealed females, suggesting that they were perhaps better at even avoid killer whales and protect their little ones from past attacks.

"We want to emphasize the importance of transnational studies to improve our understanding of marine environments and their inhabitants, as we recommend policies that work for both the health of the ocean and for the beneficiaries of its wealth. ", said Guzmán.

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More information:
JJ Capella et al., Geographical and temporal patterns of non-lethal attacks on humpback whales by killer whales in the eastern South Pacific and Antarctic Peninsula, Research on endangered species (2018). DOI: 10.3354 / esr00924