Reading about Western Australia’s terrible plan to prevent shark attacks evokes simultaneous feelings of rage and sadness. Everything about the plan is steeped in fear and myth. Attacks on humans are extremely rare (you’re more likely to be killed by your neighbor’s dog) and previous attempts to reduce shark attacks by killing sharks have failed repeatedly. But the ignorance and blood-lust of this plan isn’t the worst part.
Humans find sharks scary because they’re predators — some of the most powerful in their ecosystem. Like bears, tigers and other predators, sharks are some of the few animals that outmatch the (unarmed) human. So we dub them “dangerous” and feel completely justified in hunting and slaughtering them. What we fail to realize is that ridding the earth of threatening carnivores only puts our own survival in danger.
According to a new study, more than 75 percent of the 31 species of large land predators, such as lions and wolves, are in decline. Of these, 17 species are now restricted to less than half the territory they once occupied. Researchers warn that this carnivore cleansing “is changing the face of landscapes from the tropics to the Arctic” and creating “a widespread cascade of impacts.”
“Globally, we are losing our large carnivores,” said William Ripple, lead author of the paper and a professor in the Department of Forest Ecosystems and Society at Oregon State University, in a press release. “Many of them are endangered,” he said. “Their ranges are collapsing. Many of these animals are at risk of extinction, either locally or globally. And, ironically, they are vanishing just as we are learning about their important ecological effects.”
And what are those effects? Well among other things, carnivores play a vital role in maintaining the delicate balance of ecosystems which cannot be replaced by humans hunting the animals they normally prey on. When carnivores disappear, species like deer and elk move in. “More browsing disrupts vegetation, shifts birds and small mammals and changes other parts of the ecosystem in a widespread cascade of impacts,” explains Ripple. These include crop damage, altered stream structures, and changes to the abundance and diversity of birds, mammals, reptiles and invertebrates, said the scientists.
The reverse is also true. Where large carnivores have been protected — such as wolves in Yellowstone or Eurasian lynx in Finland — ecosystems have responded quickly, said Ripple. “I am impressed with how resilient the Yellowstone ecosystem is. It isn’t happening quickly everywhere, but in some places, ecosystem restoration has started there.”
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