Unlike other predators, humans go for the biggest fish -- and that might be a big mistake. (Guillaume Mazille)
 
Reminder: We're the worst.

Humans are some pretty ferocious predators. 
 
A new study shows just how unique humans are in their killing tendencies, and it highlights an unexpected twist. It turns out that our biggest problem may be that we target fully grown animals instead of their young.

The study, published Thursday in Science, looked at data on how different predators in the animal kingdom behave. Humans, the study found, prey on other large carnivores at nine times the rate that those large carnivores prey on one another. And we target adults in their reproductive prime much more than is natural in the animal kingdom.
 
"Our wickedly efficient killing technology, global economic systems and resource management that prioritize short-term benefits to humanity have given rise to the human super predator," lead study author Chris Darimont, the Hakai-Raincoast professor of geography at the University of Victoria, said in a statement. "Our impacts are as extreme as our behaviour and the planet bears the burden of our predatory dominance."

This imbalance is most pronounced in fishing, Darimont and his colleagues explained during a teleconference held by Science on Wednesday.
 
 Summary: (http://science.sciencemag.org/content/349/6250/784)

Modern humans evolved as cooperative hunter-gatherers whose cultural and technological evolution enabled them to slay prey much larger than themselves, across many species groups. 

One might think that those hunting skills have faded since the advent of agriculture and animal husbandry almost 10,000 years ago. Yet, as Darimont et al. show in a global analysis on page 858 of this issue (1), we are still the unique superpredator that we evolved to be. 

Analyzing an extensive database of 2135 exploited wild animal populations, the authors find that humans take up to 14 times as much adult prey biomass as do other predators. Our trophic dominance is most pronounced outside our own habitat, in the oceans (see the chart).



Darimont et al. show that the rates at which humans exploit land mammals and marine fish vastly exceeds the impacts of other predators (1). Marine fish experience "fishing through marine food webs," with different trophic groups similarly affected. In contrast, on land top predators are exploited at much higher rates than are herbivores. (P. Huey/Science)
 
Humans go after mature adult fish at a rate 14 times higher than any natural predator.

That's mostly because of conservation efforts, which have largely focused on sparing young fish. The logic there is that fishermen should leave as many babies to grow up and bolster the population as possible. But when you consider the sheer volume of adult fish being taken, the researchers report, this logic might not hold true.
 
Jeppe Kolding, an associate professor of biology at the University of Bergen who wasn't involved in the new study, agrees. Kolding has done similar research himself and says the new study is "yet another paper that's slowly churning a big issue."
 
"Catching predominantly small, juvenile fish is actually the fishing pattern that I have observed in many small-scale African fisheries over the past 30 years, and they are highly productive and sustainable," Kolding told The Post.

The big problem, in Kolding's opinion, is purely economical: Humans have developed a taste for big fish, and they'll pay for them.

"We have this sort of normative argument saying, oh, we shouldn't kill the babies," Kolding said. "But I think people see the rationale of eating the juveniles. They may object, but that's normal, because science must always be conservative when a new idea gains traction."
And it's important to note that Darimont and his team don't advocate turning all of our attention to baby fish. They think we should try to fish less, in general. They just hope that any fishing that does take place can follow a more natural scheme than exists now -- which may be an impossibly tall order, given the billions of dollars yielded by the fishing industry.

When it comes to poaching and big game hunting, the team hopes their paper can add to a growing body of work that discourages human hunters from targeting other animals for sport. They'd like to see more tourists shooting big cats with cameras, they said, and fewer shooting them with guns.

"Is it a warning? It wasn't designed as such, but I suspect many will interpret it as yet another call for humanity to reconsider its impacts on the ecosystem and ultimately upon ourselves," Darimont said.
 
 
 
 
 
 




Rachel Feltman runs The Post's Speaking of Science blog.