“Guys, we’re not seeing any sharks.”
What comes to mind when you hear those words? Is it hapless reporters at an ocean beach? Or is it swimming in a shark cage off the coast of Panama City? The news may have set your heart racing, but shark attacks are a phenomenon of the past. There are far more endangered species in our oceans today than there are sharks. And news for the past eight decades on the sharks’ percent of the world’s sharks has been exceedingly quiet.
“We usually have tried to explain this away by saying it’s not sharks, it’s something else. Just want to stop staring at the ocean,” said David Shiffman, senior scientist at Oceana, a nonprofit ocean advocacy group.
What Shiffman and other ocean conservation experts theorize is that people are misidentifying what they see. In the ocean, the number of certain types of fish can appear to have an inverse relationship to the number of sharks. What is natural fish population surge is often paired with population decline of the sharks.
Consider what is happening to the number of tiger sharks on the eastern seaboard of Florida, a coastal area popular with beachgoers. There has been a huge decline in the number of tiger sharks there: 96 percent of tiger sharks are found off the Atlantic coast of Florida, but only 8 percent of tigers are found off of the Atlantic coast of the United States. (Species like a shark’s fins are in demand in Southeast Asia, where they are made into a potent soup that is widely eaten.)
That suggests the decline of the tiger sharks isn’t tied to their number, but rather their intrinsic qualities, such as size, that are more prominent in the coast of Florida than off of the coast of the United States.
Similarly, Australia’s northern neighbor, the Philippines, is home to one of the most abundant numbers of hammerhead sharks. But while hammerheads are known to be choosy eaters and selective about which sharks they eat, they’re not choosing to avoid sharks. It just so happens that, up to recently, there were a low number of hammerheads in the ocean off of the Philippines compared to other parts of the ocean.
The population of hammerheads off of the Philippines began to rise in the early 21st century and has since increased to 1,000 tons, more than half the amount of the regional tropical hammerhead population on land, said Fabio Galindo, a doctoral candidate in Marine Ecology at the University of the Philippines in Cebu.
Why would a shark know it is feeding on a same species of shark that it has been avoiding in the ocean? Galindo and his colleagues suspect that humans have changed the squid populations in which sharks feed, making it easier for a shark to forget about its misidentification.
There’s still a lot we don’t know about sharks — and how far they have come down the food chain from their previous position atop it. Knowing more about sharks will help us better understand and protect them.
“If we don’t properly understand them, what kind of threat do they pose to us?” asked Galindo.