A corresponding study concludes that great white sharks could be some of the ocean’s best scavengers, helping to rid water of dead flesh and carcasses.
“Although rarely seen, we suspect that as white sharks mature, scavenging on whales becomes more prevalent and significant to these species than previously thought,” said Neil Hammerschlag in a press release.
Hammerschlag, director of the R.J. Dunlap Marine Conservation Program at the University of Miami, collaborated with Captain Chris Fallows and Austin Gallagher on the study, which appeared in the latest PLoS ONE. Over a 10-year period, they performed detailed observations of four shark scavenging events.
The feeding frenzies often seem to happen a certain way.
First, great white sharks detect a dead or dying whale. It may be pretty gruesome to think of a sickly whale being eaten alive, but that happens if the whale is weak enough.
If the whale is already dead, the smell of its blubber seeping into the water is like a dinner bell for the best meal of a great white shark’s life. The sharks, young and old, all zip toward the whale’s body. The researchers spotted as many as 40 different sharks doing this in a single day.
Next, the sharks often first go after the whale’s flukes — the lobes of the whale’s “tail.” These parts are likely easier to munch, and perhaps taste extremely good to great white sharks.
The sharks next go after the most blubbery parts. These would have the most calories and nutrition.
In terms of social dynamics, it pays to be big, old and mean.
“While scavenging on the whale, the sharks clearly showed a size-based pecking order,” said Fallows. “The biggest sharks came right in, targeting areas of highest blubber content, while smaller sharks fed on areas with less blubber or kept their distance from the whale, mostly scavenging on pieces of blubber that drifted away from the carcass.”
Despite the “dinner table” bullying, sharks in the area ignored whatever else they were doing, including hunting sea lions, and preferentially went for the dead whale.
“The cues (for obtaining the meat), such as the oils, emanating from this pulse of food are likely attracting much larger sharks over 4.5 meters (nearly 15 feet) from long distances to scavenge,” said Gallagher. “These data provide some credence to the hypothesis that large white sharks may be swimming known ocean corridors looking for dead, dying, or vulnerable whales.”
“By attracting many large white sharks together to scavenge, we suspect that the appearance of a whale carcass can play a role in shaping the behaviors, movements, and the ecosystem impacts of white sharks,” said Hammerschlag. “These patterns may shed some light into the ecology of this often studied — yet still highly enigmatic — marine predator.”
If you are a great white shark fan, be sure to watch the very cool video created by the researchers that summarizes the project.
(Image: Capt. Chris Fallows)
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