We first reported on some of the issues facing southern right whales in 2013 in a story detailing how kelp gulls on Argentina’s Valdés Peninsula attack and feed on the whales, capitalizing on the whales’ feeding, mating and calving habits. Since 2005, nearly 500 young southern right whales have washed up on Valdés Peninsula, prompting researchers to announce an investigation into their unexplained deaths, according to a story in The Guardian. The vast majority were calves less than three months old.

Southern right whales are one of the planet’s most vulnerable marine species and Valdés Peninsula is one of the species’ key calving areas.

“There are only a few thousand southern right whales left on the planet,” the project’s leader, geneticist Jennifer Jackson, of the British Antarctic Survey, Cambridge, told the Guardian. “We need to find out what is killing them and we think their sub-Antarctic feeding ground holds the answer.”

SHOULD WE SHOOT THE KELP GULLS ATTACKING SOUTHERN RIGHT WHALES? READ GUNNING FOR WHALES.

Southern right whales (Eubalaena australis) can grow to nearly 60 feet and weigh up to 80 tonnes. They get their name for being the right whale for hunters to pursue, Jackson told the Guardian. “They swim slowly, float when dead, and yield a great deal of oil. They were perfect targets for whalers.”

Those characteristics are also what make them vulnerable to attacks by feeding kelp gulls, who prefer whale blubber as a food source. Their attacks may be contributing to the high rate of mortality among the calves; a reduction in the whales' primary food source — krill — may also be a cause.

Approximately 10,000 southern right whales are spread throughout the southern part of the Southern Hemisphere. In the Guardian story, Jackson pointed to three theories that may explain the deaths:

• Lack of food
• Exposure to toxic algae
• Attacks by kelp gulls

“The trouble is that we know so little about the lives of southern right whales,” Jackson told the Guardian. “That is why we are going to spend the next two years studying them in great detail.”

Jackson's study, in collaboration with researchers at St. Andrews University and other groups, will be conducted over a two-year period. Researchers will use acoustic devices and drones to study whales and DNA samples will be taken to identify individual animals and to determine their hormone levels and reproductive status. Precise numbers of populations will be established while old whaling logbooks will be consulted to estimate how many southern right whales used to inhabit the seas around South Georgia. Surveys of numbers of krill will also be taken.

READ SCIENCE EDITOR ROBIN MCKIE’S COMPLETE STORY IN THE GUARDIAN.