VANCOUVER, British Columbia — For millennia, killer whales have captivated our imaginations with their intelligence, social bonds, and powerful hunting abilities. But despite decades of research, many aspects of their daily lives and physiology have remained a mystery. Now, a groundbreaking study led by scientists at the University of British Columbia and the Institute for the Oceans and Fisheries has shed new light on the breathing patterns and energy expenditure of these magnificent marine mammals.
The study, published in PLOS ONE, used an innovative approach combining drone footage, biologging devices, and advanced statistical modeling to unravel the secrets of killer whale respiration. By attaching special tags to the whales, the scientists were able to record their diving behavior in unprecedented detail while drones flying overhead captured video of the whales’ surface activities.
One of the key findings of the study is that killer whales take a single breath during each trip to the surface, regardless of whether they are resting, traveling, or foraging for food. This may seem like a small detail, but it has important implications for understanding the energy demands of these top predators.
You see, every breath a killer whale takes is a window into its metabolism. Just like us, whales need oxygen to fuel their daily activities. The more energy they expend, the more oxygen they need to take in. By counting the number of breaths and measuring the time between each surfacing, scientists can estimate the amount of energy a whale uses during different behaviors.
However, it’s not as simple as just counting breaths. Killer whales, like all mammals, have complex respiratory systems that allow them to store oxygen in their blood and muscles while diving. This means they don’t necessarily need to breathe in perfect sync with their physical exertion. Instead, they may build up an “oxygen debt” during intense activities like hunting, which they then repay later with a series of deep breaths at the surface.
To account for this, the research team had to get creative. They used drone footage to categorize each killer whale’s behavior as either resting, traveling, or foraging and then matched this information with the diving data from the tags. Next, they used a sophisticated statistical model called a hierarchical hidden Markov model to fill in the gaps and predict the whales’ behavior during dives that weren’t captured on camera.
The scientists discovered that both juvenile and adult male killer whales breathe most frequently while traveling, followed by foraging and finally resting. This suggests that swimming long distances is actually more energetically demanding for killer whales than hunting for food – a finding that challenges some previous assumptions.
On average, the juvenile whales in the study took between 1.2 and 1.6 breaths per minute, while the adult males breathed a bit more frequently at 1.3 to 1.8 breaths per minute. Using these respiration rates, along with estimates of the whales’ body sizes and oxygen storage capacities, the team was able to calculate the approximate amount of energy the whales expended during each activity.
For the juveniles, foraging required around 7.3 liters of oxygen per minute, traveling used about 7.4 liters, and resting consumed 6.7 liters. The much larger adult males had correspondingly higher energy needs, using a whopping 35.2 liters of oxygen per minute while foraging, 43.6 liters while traveling, and 25.8 liters while resting.
These estimates provide valuable insights into the daily energy budgets of killer whales and can help scientists and policymakers better understand the food requirements of these ocean predators. This information is especially critical in a rapidly changing ocean, where shifting prey populations and increasing human activities can put pressure on killer whale populations.
But the implications of this study go beyond just killer whales. The innovative techniques developed by the research team, combining biologging, drone observations, and advanced statistical modeling, could be applied to other marine mammal species to unveil their own respiratory secrets. As our technology and analytical methods continue to evolve, we may soon be able to paint an increasingly detailed picture of the hidden lives of these fascinating creatures.
StudyFinds Editor-in-Chief Steve Fink contributed to this report.