For the first time, researchers track the full migration cycle of an Australian southern right whale

Migration is a tricky endeavour. There are numerous obstacles, not to mention many kilometres to travel. When you think of migration, you may think of birds first. When you picture the distances some of these birds travel, you might expect they migrate along the shortest route possible and, for ease, likely take the same route back. And although some birds do travel the same route there and back, many do not. 

Like countless migratory birds, many whale species also travel vast distances, some thousands of kilometres every year between breeding and feeding grounds. In fact the longest documented mammal migration, a 22, 511 km round-trip was completed by a critically endangered western gray whale. Researchers study these routes, or blue corridors, using satellite tracking, photo-identification, and Indigenous Knowledge. With the help of satellite tags, researchers from the University of Western Australia and Macquarie University, in collaboration with researchers from the University of Auckland Waipapa Taumata Rau, were able to follow the complete migration cycle of an Australian southern right whale for the very first time.

Nebinyan is an adult southern right whale that was tagged of Cheyne Beach, Western Australia, on 19 September 2022.

Blue corridors are critical ocean habitats for migratory marine species. Whales rely on these habitats for their survival. These are areas where they feed, mate, give birth, nurse young, socialise or migrate. Protecting Blue Corridors is a global conservation project by WWF designed to safeguard the migration routes of whales who navigate long distances between breeding and feeding areas each year.

The migration route stretched over 6,000 km, from Western Australia to Antarctica and back. These southern right whales that migrate to Antarctica are likely feeding on Antarctic krill. To the surprise of the researchers, one year after being tagged near Albany, Australia, the migrating whale, Nebinyan, named after an Aboriginal whaler from the 1840s, turned around and followed almost the exact same route back again.

Dr Kate Sprogis, Adjunct Research Fellow at UWA’s Oceans Institute and School of Biological Sciences based at the UWA Albany campus, is a co-lead for the Mirnong Maat project which investigates the migration patterns of Australian southern right whales. WWF’s Whales and Dolphins Initiative was excited to ask Kate questions about this incredible research.

Dr Leena Riekkola and Dr Kate Sprogis setting up the drone for flight.

Why is it important to know which routes southern right whales use to migrate?

Mirnong Maat research team: Kate Sprogis, Simon Childerhouse, Emma Carroll, Rob Harcourt and Leena Riekkola.

When the whales leave our Australian coast around October, it is not until May/June of the next year that the whales return. Over these warmer months, the whales head to their feeding grounds. Before our research project Mirnong Maat, it was unknown if southern right whales from Western Australia all migrated to the same foraging grounds and used the same migration routes or if the whales fed in the same area as southern right whales from New Zealand (an area south of the Australian Bight). Consequently, half their life remained a mystery and you cannot protect what you do not know.

We now know that the whales have highly variable migration routes, with some using the Subtropical Front, some migrating to French Subantarctic Islands (Kerguelen and Crozet), and some migrating to Antarctica. It is possible that the whales are feeding on different prey. For example, the whales migrating to Antarctica are likely feeding on Antarctic krill, and perhaps the whales utilising the Subtropical Front are feeding on copepods. With more data across several years, we hope to find out if these foraging locations are consistent across years or if we discover more foraging areas. 

This knowledge equips us with information on the areas of importance for southern right whales. The data is being used in Biologically Important Areas (BIAs) mapping by the Australian Government and can be used in the conservation of this endangered species.

Describe the importance of engaging local First Nation members.

The Mirnong Maat project is based on Menang/Merningar Noongar Country. Merningar lore is place-based. It bonds people, specific places, and all aspects of Country. Merningar Noongar people are coastal people, recognised as whale or shell maat people who have a long-time connection with the whales that frequent these southern shores. Merningar Noongar people are a part of the longest-living culture on Earth and have lived along this coastline for approximately 60,000 years. ‘Nebinyan’ the whale, is named after a respected member of the Merningar/Menang Noongar language group, known as the whale man. Nebinyan was one of the first whalers during the colonial industry, which began in the area in the 1840s. Meet more of the whales.

Research shows that southern right whales have adjusted their foraging grounds over the past 30 years as climate change altered where their prey could be found. Do you think they can keep doing this?

There are changes occurring in the Southern Ocean ecosystem due to global warming, where, the IPCC states, “it is unequivocal that human influence has warmed the atmosphere, ocean and land.”

It is predicted that the warming of waters and loss of sea ice will alter the distribution and density of prey for whales, such as krill and copepods. Off South Africa, researchers found that southern right whales shifted their migration paths to different foraging patches as perhaps their preferred prey became sub-optimal or unavailable.

A sentinel species can be used to detect climate change impacts in the Southern Ocean. For example, if the prey of whales shifts distribution or changes in density, then this change can have a negative influence on the whales. It has been shown that southern right whales have a decrease in their reproductive output when foraging is affected as they are not able to gain the required fat stores to reproduce successfully.

It has become increasingly important to understand the linkages of southern right whales and environmental conditions on their feeding grounds, as some southern right whale populations have experienced declines in reproductive success or mass mortality events.