Recycling of life, one shark bite at a time
Great white shark, ready for a meal. Photo: Fedorenko Gennady.
It turns out you really can get a free lunch—at least, if you're a great white shark.
A group (or, a shiver, if you prefer a more alliterative group name) of sharks found themselves presented with just such an unexpected buffet earlier this month, when a 36-foot Brydes whale (Balaenoptera edeni) was found drifting off the coast of South Africa.
Likely the tragic result of a ship strike—a major cause of injury and death to large whales, including the endangered North Atlantic right whale we're working to protect—the massive 10-ton remains was on a steady course for the shoreline, presenting a serious problem for local authorities. The recently departed whale would attract hungry sharks, which would in turn increase the likelihood of awkward shark/human encounters.
In a brilliant solution, the South African navy made the best of the whale's unfortunate death, towing it out to a remote area where the sharks could dine undisturbed—and under the close eye of scientists. Alison Kock, project leader at the Save Our Seas Shark Centre, characterized the nine-day marathon feast as "an unparalleled opportunity to document white shark behaviour." (Click on the image to advance to the next photo. Viewer discretion advised, if you're presently in the midst of your own meal.)
At the close, little remained except for bone and muscle, the ideal result. Over 30 different sharks had dropped by to help themselves to delectable morsels, demonstrating themselves to be picky and careful eaters. Interestingly, Alison noted:
[W]e documented numerous examples showing that the sharks knew exactly what they wanted (the [high calorie, energy rich] blubber) and if they got a mouthful of muscle they often spat it out. This may provide some insight into why so many bites on humans ... are a bite-and-release only.
And in much the same way, Thanksgiving Day meals have been known to affect humans:
Some of the sharks we observed were gorging on the blubber and you could actually see their bellies getting fuller. Some would arrive quite skinny and by the end of their session they looked pregnant with their bellies bulging.
Great whites have a long-suffering reputation in the public's eye, helped along in no small way by Jaws (book and movie versions) and by all those teeth. In reality, we're not as delicious as we think we are. Great whites much prefer fish (including, occasionally, other sharks), seals and the like. These top predators—like all members of the food chain, large and small, serve a key role in ensuring oceans maintain a healthy balance. As Alison explained:
This is the ultimate example of the very important role sharks play in the ecosystem. That of recycling life, and of keeping our oceans healthy by removing dead and decaying animals like dead whales.
Given their leisurely rate of growth and maturity, sharks are particularly vulnerable to overfishing. A study published in the journal Science in 2003 documented steep declines of species like hammerheads (up to 89 percent) and great whites (up to 79 percent) over the preceding two decades. In recent years, Earthjustice has gone to court in efforts to protect these species and allow them to adequately rebuild their populations.
Read more about our oceans work here at unEARTHED. And visit Save Our Seas for more on the great white feast.