Marine researcher John Totterdell has dedicated his career to studying killer whales, or orcas, focusing on populations off the West Australian coast. With decades of fieldwork, he has illuminated their intricate social structures, opportunistic hunting behaviors, and critical role in marine ecosystems. John Totterdell’s research highlights two distinct groups of killer whales in the region. A temperate population inhabits the southern coastline, while a tropical group visits the Ningaloo Reef during the humpback whale migration. The latter times its arrival to prey on newborn humpback calves, significantly impacting the species’ lifecycle and contributing to the balance of marine ecosystems.
Stemming from their diverse ecological adaptations, there is a debate over whether to classify killer whales as a single species or to divide them into separate categories.
John Totterdell
John Totterdell delves into the eco-types found in the Antarctic and sub-Antarctic, including the elusive Type D killer whale. by its unique morphology – a rounded melon, smaller eye patches and a falcate dorsal (narrow, pointy and swept back)—this eco-type was rediscovered in the Drake Passage after being presumed extinct for over 50 years. John’s expedition to document these animals revealed their distinctiveness, though genetic analysis determined they do not warrant classification as a separate species.
Biopsy Sampling and Whale Hunting
Biopsy sampling, a key tool in John’s research, provides insights into kinships (family structures), diet, and pollutant exposure. Using crossbows, researchers collect tissue from whales, while drones offer a less invasive approach. This methodology has proven invaluable in studying the Ningaloo population, whose predation on humpback calves underscores their ecological significance. Up to 400 calves are taken annually by these killer whales, a top-down process that assists in ecosystem stability and helps regulate the humpback population, which has exceeded pre-whaling numbers. While these predations can be distressing to observe, this regulation or ‘culling’ of the fully recovered humpback population may, in turn, reduce the competition of Antarctic krill, a critical food source facing threats from climate change and overfishing.
Humpback whales exhibit fascinating behaviors in response to killer whale threats. Male escorts often accompany mothers and calves, likely motivated by mating opportunities. These escorts sometimes defend calves, but their role remains complex and multifaceted. John recalls accounts from colleagues who have observed humpbacks intervening in killer whale hunts, aiding unrelated species like seals and penguins, suggesting a deep-seated antagonism toward killer whales.
One of the most remarkable observations that I made was the first documented case of killer whales hunting and killing an adult blue whale.
John Totterdell
This unprecedented event showcased the apex predator’s capability to target the ocean’s largest mammal. Such findings contribute to understanding killer whale diets, which vary between populations and regions. While Ningaloo killer whales specialize in humpback calves, they opportunistically hunt other species, including dolphins, tiger sharks, and even squid.
“With exceptional intelligence and coordinated teamwork, killer whales, the planet’s largest attack predator, also exhibit a deep caring and nurturing nature, forming lifelong familial bonds with their distinct local language”. A highly evolved animal widely distributed and performing positive ecological functions in all oceans of the world. Perhaps we could learn from them.
The role of Citizen Science in Understanding Whale Behaviour
Citizen scientists play an integral role in John’s work. Photos and videos submitted by marine enthusiasts have expanded the understanding of killer whale distributions and behaviors. This collaboration has been especially fruitful in areas like Ningaloo and Bremer Bay, where local operators and enthusiasts frequently encounter killer whales.
Killer whales’ matriarchal societies set them apart from many other species. Females lead hunts and serve as the backbone of the pod, with males often dependent on their maternal groups. John’s observations of inter-pod interactions, mating behaviors, and even what he describes as “playful male bonding” reveal the species’ social complexity. In one striking example, a matriarch facilitated an introduction between her pod’s young male and another pod, showcasing the depth of their cooperative and communicative behaviors.
John’s research offers a window into the lives of one of the ocean’s most intelligent and formidable predators. From their role in maintaining marine balance to their rich social structures, killer whales remain a subject of endless fascination. Through the combined efforts of scientists and citizen scientists, our understanding of these remarkable creatures continues to deepen, ensuring their conservation for generations to come.
When Ted Cheeseman first visited Antarctica in the early 1990s, the seas were eerily quiet. Once teeming with whales, the waters around South Georgia had been emptied by whaling decades earlier.
