Nav: Home

First study of Humpback whale survivors of orca attacks in the Southeastern Pacific

November 06, 2018

Humpback whales bear stark battle scars from violent encounters with orcas, also known as killer whales. Analysis of rake marks on more than 3000 humpback whale tails or flukes suggest that attacks on these undersea giants may be on the rise, according to a new study in Endangered Species Research.

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

Orcas, Orcinus orca, like humans, are apex predators. Although they can feed on more than 20 different species of cetaceans, they usually prefer sea lions, fur seals, fish and sea birds. "Because the chances of observing rake marks on young, vulnerable whales increased in the last 20 years, we think that killer whale attacks on humpback whales may be more common now than they were in the past, perhaps due to the recovery of whale breeding stocks in the Southeast Pacific after hunting was prohibited," said Juan Capella, lead author and marine biologist from Whalesound Ltd. in Chile.

This extraordinary international team studied photos of whales at shallow, warm-water breeding grounds in Panama's Las Perlas Archipelago, Gorgona Island and Malaga Bay in Colombia and Salinas and Machalilla in Ecuador and at cold water feeding grounds in Chile's Magellan Strait and the Gerlache Strait off the western Antarctic Peninsula. They found that 11.5 percent of adult whales and 19.5 percent of calves carried battle scars, numbers similar to those reported from the North Pacific, the North Atlantic, eastern Australia, Tonga and New Caledonia. "The number of scars borne by an individual whale didn't seem to change from year to year, suggesting that orcas primarily attack calves during their first migration," said Fernando Felix, marine biologist from the Pontifica Universidad Catolica and the Whale Museum (Museo de Ballenas) in Ecuador. They carry their scars for the rest of their lives."

Because young whales at feeding grounds had more scars than young whales at breeding grounds, researchers suspect that orcas prefer to attack young whales. Scarred female whales who were attacked by orcas as calves arrived at Magellan feeding areas with a higher number of calves than non-scarred females, suggesting that maybe they were better at evading orcas and defending their young from attack because they had survived an attack in the past.

"We want to underscore the importance of transnational studies to better our understanding of marine environments and their inhabitants as we recommend policies that work both for the health of the ocean and for the beneficiaries of its wealth," Guzmán said.
-end-
Author affiliations also include: Fundación Yubarta, Colombia, and Instituto de la Patagonia, Chile.

Reference: Capella, J.J., Félix, F., Flórez-González, L., Gibbons, J., Haase, B. and Guzman, H.M. 2018. Geographic and temporal patterns of non-lethal attacks on humpbacks whales by killer whales in the eastern South Pacific and the Antarctic Peninsula. Endangered Species Research. Doi: 10.3354/esr00924

Smithsonian Tropical Research Institute

Related Whales Articles:

Meals on the go: The physics of whales' eating habits
Saint Louis University professor of physics Jean Potvin, Ph.D., and colleagues detail for the first time how baleen whales use crossflow filtration to separate prey from water without ever coming into contact with the baleen.
Baleen whales' ancestors were toothy suction feeders
Modern whales' ancestors probably hunted and chased down prey, but somehow, those fish-eating hunters evolved into filter-feeding leviathans.
Scientists tag humpback whales in southeast Pacific
Whales from both poles migrate long distances to breed in tropical waters.
Save the whales
Benioff Ocean Initiative announces first project, commits $1.5 million to finding solutions to whale deaths caused by vessel collisions.
Researchers reveal first sightings of rare whales off New Zealand coast
For the first time in New Zealand waters an extremely rare grouping of Shepherd's Beaked Whales has been spotted from a University of Otago research vessel off the coast of the city of Dunedin in the South Island.
More Whales News and Whales Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.