Humpback whales create nets of bubbles to trap their prey of small fish and krill before feasting on them in fascinating video
- Researchers combined ‘whale-cam’ footage with aerial video taken from a drone
- The whales are seen blowing spiral nets of bubbles that rise up to the surface
- This lets them efficiently ensnare their prey, which can then be eaten en-masse
- The feeding precedes the long migration down to warmer waters for the winter
Fascinating footage reveals how humpback whales create spiral-shaped ‘nets’ composed of bubbles in order to entrap their prey.
Researchers captured the unprecedentedly detailed footage of the unusual surface feeding practice — dubbed bubble-net fishing — in waters off of Southeast Alaska.
To use this technique, whales round up fish or krill inside a circle of bubbles they have blown from their blowholes.
As the whales then rise towards the surface, the fish become trapped in the bubble net, within which the huge humpbacks can then feast.
Fascinating footage reveals how humpback whales create spiral-shaped ‘nets’ composed of bubbles in order to entrap their prey
Marine biologist Lars Bejder of the University of Hawai’i at Mānoa and colleagues used drones to capture a bird’s-eye view of the whales feeding.
This was combined with data collected from the whale’s point-of-view by cameras and sensors stuck to the marine mammals’ bodies with suction cups.
Together, the data provides scientists with an unprecedentedly detailed look at this rare and remarkable feeding method.
‘The footage is rather groundbreaking. We’re observing how these animals are manipulating their prey and preparing the prey for capture,’ said Professor Bejder.
‘So it is allowing us to gain new insights that [we] really haven’t been able to do before.’
The footage was captured as part of a project that is investigating why humpback whale numbers seem to be on the decline.
Researchers are particularly focused on the impacts of both shifts in habitat use and changes in food availability linked to climate change and diminished prey numbers.
Around 3,000 humpback whales visit Alaska every summer during their feeding period, while up to 10,000 migrate to Hawaii in the winters to breed.
The whales captured in this footage are preparing themselves for the 3,000 mile (around 4,800 kilometre) -long haul down towards the warmer winter waters around Hawaii by feasting on fish.
They will not eat until they return to Alaska’s waters several months later.
The findings of the researchers’ study will help to shine light not only on how the whales feed, but also how often, what they feed on and the impact such feeding frenzies have on the development of their bodies.
Researchers captured the unprecedentedly detailed footage of the unusual surface feeding practice — dubbed bubble-net fishing — in waters off of Southeast Alaska
Marine biologist Lars Bejder of the University of Hawai’i at Mānoa and colleagues used drones to capture a bird’s-eye view of the whales feeding, along with data collected from the whale’s point-of-view, pictured, by cameras stuck to the mammals’ bodies with suction cups
‘We have two angles, and the drone’s perspective is showing us these bubble nets and how the bubbles are starting to come to the surface and how the animals come up through the bubble net as they surface,’ said Professor Bejder.
‘The cameras on the whales are telling us this from the animal’s perspective, so overlaying these two data sets is quite exciting.’
‘In Hawai’i it’s a breeding and resting ground. When they get to Alaska it’s a foraging ground.’
‘We’re trying to understand what that whole migration costs these animals and also how much prey these animals have to consume to maintain this whole migration.’
‘The footage is rather groundbreaking. We’re observing how these animals are manipulating their prey and preparing the prey for capture,’ said Professor Bejder. ‘So it is allowing us to gain new insights that [we] really haven’t been able to do before.’
The footage was captured as part of a project that is investigating why humpback whale numbers seem to be on the decline. Researchers are particularly focused on the impacts of both shifts in habitat use and changes in food availability
HUMPBACK WHALE POPULATIONS AND THEIR THREATS
Humpback whales live in oceans around the world. They travel incredible distances every year and have one of the longest migrations of any mammal on the planet.
Some populations swim 5,000 miles from tropical breeding grounds to colder, plentiful feeding grounds – this is why it is difficult to estimate population size, according to the National Oceanic and Atmospheric Administration (NOAA).
Of the 14 distinct populations, 12 are estimated to number more than 2,000 humpback whales each and two are estimated to number fewer than 2,000.
Humpback whales live in oceans around the world. They travel incredible distances every year and have one of the longest migrations of any mammal on the planet
Some populations (such as those off eastern and western Australia) are believed to number in excess of 20,000 animals—a remarkable recovery given that the same populations were almost eradicated by whaling almost sixty years ago.
By contrast, the smallest known population is one which inhabits the Arabian Sea year-round, and may number as few as 80 individuals.
Threats to humpback whales include decline in food like Krill due to a combination of climate change and industrial-scale fishing.
Humpback whales can become entangled by many different gear types including moorings, traps, pots, or gillnets.
Once entangled, if they are able to move the gear, the whale may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury.
There is evidence to suggest that most humpback whales experience entanglement over the course of their lives, but are often able to shed the gear on their own.
Inadvertent vessel strikes can injure or kill humpback whales.
Humpback whales are vulnerable to vessel strikes throughout their range, but the risk is much higher in some coastal areas with heavy ship traffic.
Underwater noise threatens whale populations, interrupting their normal behaviour and driving them away from areas important to their survival.
Sound has been shown to increase stress hormones in their system and mask the natural sounds humpback whales require to communicate and locate prey.
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