Uncovering whale superhighways in the Southern Ocean

© UCSC-WWF-Chris Johnson -PermitUnderNOAA

Antarctica's majestic great whales have long captured the fascination of researchers, but studying these ocean giants is challenging. Technology is an indispensable tool in unravelling the mysteries of these enigmatic creatures. To study whales in Antarctica and other parts of the world, scientists rely on inflatable zodiacs for stealthy manoeuvring around giant icebergs and deploy special tags to uncover secrets of whale ecology. They use drones to gain a bird's-eye view in areas that are tricky to get to, and exhibit creative engineering when faced with rapidly changing weather conditions.

In a recent expedition to Antarctica, Chris Johnson, the Global Lead for WWF's Protecting Whales and Dolphins Initiative, joined a team of esteemed whale ecologists led by Dr. Ari Friedlaender from the University of California Santa Cruz. Their mission was to investigate Antarctica's great whales and gain insights into their blue corridors amid a changing climate. This ambitious undertaking was made possible through a partnership between Intrepid Travel and WWF-Australia.

Protecting Blue Corridors is a global conservation project done in collaboration with the marine mammal science and policy community. It identifies strategies to safeguard the vital habitats of whales, including their annual migration routes between breeding areas in the tropics and feeding grounds in the poles.

“Many baleen whales, such as humpbacks, fin whales, sei whales, southern right whales, and Antarctic minke whales, migrate here to feed primarily on Antarctic krill. However, crucial details about their feeding areas and distribution still elude researchers,” says Chris Johnson. “As climate change and krill fishing intensify in the region, the urgency to expand our knowledge of their critical foraging areas, and design and implement effective protection measures is paramount.”

Using traditional and innovative research techniques

To delve into the world of whales, the research team employed cutting-edge technology, including digital tags and drones, to identify and map vulnerabilities in their habitats due to climate change. Such innovative approaches are increasingly being used to monitor whale populations in remote areas like the Antarctic.

The digital tags, no larger than an iPhone, are non-invasive and attach to the backs of whales using small suction cups. With special research permits allowing proximity to the whales, the team uses a 5-meter zodiac boat to approach and attach a tag onto a whale’s back using a long pole. After a predetermined period, the tag automatically detaches and floats to the surface, allowing for easy collection by the research team.

By tagging whales, scientists gather invaluable data, including video recordings, audio samples, and 3D tracks of the whales' movements during diving and feeding. This wealth of information sheds light on their migration patterns, feeding frequency, resting habits, feeding depths, interactions with other species, and the impacts of environmental conditions.

Additionally, the research team collects tiny biopsy samples of skin and blubber to measure hormone levels, stress indicators, and determine the sex of each whale. To obtain a biopsy sample, researchers use a low-powered crossbow equipped with hollow-tipped darts. The dart bounces off the whale collecting a small amount of blubber—roughly half the size of a pinkie finger—before falling into the water for retrieval. The entire process is benign to the whale and resembles a mosquito bite.

“Understanding the correlation between feeding behaviour and factors like sea ice availability and prey abundance, along with the insights gleaned from biopsy sampling and other techniques, equips us with information about the health of these animals, their migration patterns, and the potential impacts of climate change and human activities,” says Dr. Ari Friedlaender from the University of California Santa Cruz. “The more comprehensive our understanding of a species, the better we can identify critical areas in need of protection from human interference.”

Discovering long-term trends from above

Researchers also employ a technique called photogrammetry to study the body condition of whales. By utilizing drones to capture aerial images of the whales, photogrammetry enables scientists to extract information and obtain precise measurements of these magnificent creatures from above.

The Whale Unit at the Mammal Research Institute at the University of Pretoria has spent over five decades studying southern right whales that breed along the coast South Africa and feed in sub-Antarctic areas. In recent years, the population numbers of these whales in coastal South Africa started fluctuating. The research team also noticed that females were thinner and experience longer calving intervals up to four or five years.

To investigate these changes in body condition, the team turned to photogrammetry. In the late 1980s, South African researchers captured aerial photographs of southern right whale cow and calf pairs using a plane. To determine the extent of changes in body condition, the team applied photogrammetry techniques to compare the images from past and present.

The results indicated a 23 per cent reduction in maternal body condition of South African southern right whales since the late 1980s. Parallel to this decrease, data from skin samples taken in the early 1990s and the 2010s revealed that their foraging location had shifted north, meaning that their prey has moved. South African southern right whales consume zooplankton, and their primary source is Antarctic krill. Since baleen whale body condition can be directly linked to prey abundance, these results illustrate a reduction in foraging success and, possibly, reduced prey availability. 

A network of Marine Protected Areas (MPAs) is a crucial solution for the Southern Ocean

Antarctic krill heavily depend on sea ice, and fluctuations in sea ice levels around Antarctica directly impact the krill population's abundance. Competition for these semitransparent crustaceans is high. Baleen whales depend on Antarctic krill, as do many other marine animals, such as seals, seabirds, and fish.

The endeavor to study Antarctic whales is of paramount importance as WWF and its partners use this science to help inform and establish marine protected areas across the vast expanse of the Southern Ocean. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has committed to establishing a comprehensive network of MPAs around the continent. MPAs here will limit or ban krill fishing with the aim to protect biodiversity and foster resilient marine ecosystems for nature and people. Effective implementation of MPAs will aid in the preservation of Antarctic biodiversity, including krill populations and whales, while also providing space for marine life to adapt to the impacts of climate change.