Tracking Southern Right Whales in Península Valdés, Argentina
Dr. Marcy Uhart has been investigating southern right whale health in their breeding ground at Península Valdés, Argentina for more than a decade. But until now, she -- and everybody else -- knew very little about where the whales actually go when they leave the area after the breeding season.
But that changed this fall, when five southern right whales were tagged with GPS tracking devices – the first time ever in this population.
“The whales here have been studied since the 1970s, but where they go beyond their few months at Península Valdés is still a mystery, even after forty years,” said Dr. Uhart, Director of the Latin America Program at the UC Davis One Health Institute. “Where they spend several months each year is a key component of their biology that we don’t know.”
Southern right whales are suffering from an unprecedented mortality event in Península Valdés, Argentina. Over the course of 2012 alone, 116 dead southern right whales were discovered in the local breeding area. This is the highest number of dead whales ever recorded in one season for this species. Several hypotheses are being studied to explain this problem, including the effects of kelp gulls that feed on the skin and blubber of live whales, and potential nutritional deficiencies.
The GPS tracking of the whales will help determine where the whales go when they leave Península Valdés and if the whales are passing through areas that could be a threat to their health.
“There could be some issue in the feeding grounds, or the migration paths where they could be encountering fishery operations, oil drilling and exploration operations or shipping lanes,” said Dr. Uhart.
Of the five whales tagged, two were females with calves and three were juveniles.
This is the first time that the Península Valdés southern right whales have been tagged by satellite transmitters and, naturally, it has come with challenges. To tag the whales, the team of researchers was on the water for two weeks. They constructed a raised platform on the boat so that tagging experts could stand to dart the device vertically into the whales’ thick layer of blubber. This is made extra challenging because years of kelp gull attacks on the whales’ backs have prompted the whales to learn to swim with their backs hidden below the surface as often as possible. This makes it difficult to get a clear angle.
The trackers, which are about 12 inches long, do not cause the whales harm.
“The juveniles didn’t react,” said Dr. Uhart. “They stayed around the boat for a long time afterwards and continued to come very close to it after being tagged.”
Over time, the tracking device will gradually slip out of the whale – kind of like how a small splinter slowly works its way out of your skin. The study period is set to last ninety days, which is long enough for the whales to reach their feeding grounds, but short enough to be fairly certain the devices won’t come out before it’s done.
It’s a short study, but the data began proving its value almost instantly: after just two weeks of tagging the whales, Dr. Uhart was already surprised by some patterns in their movement.
“The mother-calf pairs have been moving around the entire gulf,” she says. “I thought that they were much more static and actually stayed around the same beaches for longer, but they’ve been covering the whole area, and the three juveniles almost immediately headed south-east to the feeding grounds.” (See the map above).
By Jasjeet Dhanota
This international effort includes members from the Wildlife Conservation Society (WCS), the Aqualie Institute of Brazil, the National Oceanic and Atmospheric Administration (NOAA), and Cascadia Research Collective, working in cooperation with Fundación Patagonia Natural, Instituto de Conservación de Ballenas, Ocean Alliance, the University of California, Davis, with the endorsement of the Wildlife Service, Tourism Secretariat, and Ministry of the Environment of Argentina’s Chubut Province.