As we’ve all suspected, humanity is just a bottomless swarm of unquenchable thrill killers.
“Whereas predators primarily target the juveniles or “reproductive interest” of populations, humans draw down on the “reproductive capital” by exploiting adult prey”, said Tom Reimchen, professor of biology at the University of Victoria in British Columbia, Canada.
“Our impacts are as extreme as our behaviour and the planet bears the burden of our predatory dominance”. Some fish stocks worldwide have collapsed, and the fish that remain are getting smaller and maturing earlier than they used to, producing less offspring, as human fishing practices drive their evolution.
A little fish called the three-spined stickleback had many predators, mostly diving birds and bigger fish such as trout, but Reimchen found they overwhelmingly took the babies and never more than five per cent of the adults in a year.
But the researchers said there are already examples of fisheries that do this, such as the Newfoundland lobster fishery, which sets traps with openings too small for large lobsters to enter.
He said that taking bigger fish or animals “has remarkable short-term benefits” in terms of food production, but poses serious long-term implications. Not only that, we also target an abnormally high number of other predators, not just for food but also-as with Cecil the lion-for sport.
Reimchen first came up with the idea of comparing humans to other predators while conducting research at a lake on B.C.’s Haida Gwaii islands in the 1970s.
Renowned conservation expert Stuart Pimm of Duke University, who wasn’t part of the study, praised it. “We ought to be harvesting animals that are about to die from other causes”, he said.
In fact, Darimont said, fish and animals have evolved strategies for reproduction specifically to deal with predation of their young.
Writing in the journal Science, the team concluded: “Our global survey revealed that humans kill adult prey, the reproductive capital of populations, at much higher median rates than other predators, with particularly intense exploitation of terrestrial carnivores and fishes”. A truly sustainable model, they argue, would mean cultivating cultural, economic and institutional change that places limits on human activities to more closely follow the behaviour of natural predators.
After the Second World War, fishing fleets began to range out of coastal waters, with large amounts of fuel, sonar fish finders and freeze-at-sea technology that allowed us to exploit fish populations far from the coastal waters plied by our ancestors.
The researchers then compiled an extensive database of 2,125 species of predators around the world on both land and sea, and how they impact populations of other animals.