As Earth’s Superpredators, Can We Change How We Use Wildlife?

Candice Gaukel Andrews October 13, 2015 15
When a top predator such as a lion is lucky enough to take down a single animal, it is almost always one that is weak, young or very old. ©Patrick J. Endres

When a top predator such as a lion is lucky enough to take down a single animal, it is almost always one that is weak, young or very old. ©Patrick J. Endres

Would you mind living next door to a top predator? It’s a question I’ve asked you before. It seems that when it comes to bears, lions or wolves, we humans, as a whole, can’t get rid of our four-footed, predatory neighbors fast enough.

Those top predators, however, have far more to fear from us than we from them. And, indeed, so does any other species that humans deem a food source or a trophy to hang on the wall. According to a new study, we are the Earth’s “superpredators,” with methods so devastating that they disrupt global food chains, shrink fish sizes and alter the course of other species’ evolution or even completely drive them to extinction.

Do you think there’s a possibility that we could learn to commercially produce food and hunt in a way that is more sustainable and more like the way the planet’s other large predators harvest prey? Or are our ways too deeply entrenched to hope for change?

The danger of us

The rate at which humans exploit land mammals and marine fish vastly exceeds the impacts of other predators (H=herbivore; C=carnivores; TP= top predators). ©P. Huey/”Science”

The rate at which humans exploit land mammals and marine fish vastly exceeds the impacts of other predators. ©P. Huey/”Science”

Any traveler to Africa may have seen this scenario unfold: a lion approaches a group of zebras, and, if it’s lucky, manages to take down a single animal that is weak, young or very old. In contrast, typically when humans hunt, they search for the biggest, strongest or most charismatic animal, usually choosing one in its prime reproductive years.

This fundamental difference makes us the most devastating predator on Earth. In a study, which was published on August 21, 2015, in the journal Science, 2,125 interactions between predators and their prey were examined. Results showed that worldwide, humans kill carnivores at an average annual rate that is nine times higher than the pace at which carnivores kill each other: while large predators such as bears, lions and wolves kill about 2 percent of their populations annually—usually during competition for dominance—we kill 18 percent of the carnivore population.

Interestingly, humans kill the same proportion of large herbivores (such as deer, elk or moose) that other carnivores do: 5 percent for other carnivores and 6 percent for humans. But things get worse again when it comes to the world’s fish populations: commercial fisheries catch adult fish, such as cod and tuna, at 14 times the rate that natural marine predators do.

The study’s lead author, Chris Darimont, the Hakai-Raincoast professor of geography at the University of Victoria in British Columbia, says that we consider our focus on targeting adult fish sustainable because it supposedly allows smaller, juvenile fish to have greater access to food and then to grow large enough to also be caught. But in some cases when the large adults are killed, only smaller ones reproduce. That can mean they lay fewer eggs, and the fish that do hatch are smaller. This way of managing fish populations also removes nutrients—in the form of large, dead fish—from the ecosystem. It’s one of the reasons why there is less biomass in the ocean now than there used to be. In fact, many fish species and entire fisheries have become depleted in recent years.

Humans kill roughly the same proportion of large herbivores that other carnivores do. ©Justin R. Gibson

Humans kill roughly the same proportion of large herbivores that other carnivores do. ©Justin R. Gibson

Our industrial-scale fishing also results in a large amount of bycatch, or the killing of not just targeted fish but other fish species, as well as birds and sea turtles. That makes us a more destructive predator on top of it and likely the only one that commonly and at very high rates kills animals we don’t intend to.

Likewise, when we target an animal’s reproductive age class and especially the larger, more fecund animals, we significantly decrease the reproductive capacity of that population. If you kill an adult animal, it will take years for another to grow up and take its place. But if you kill a juvenile, it will take only until the next breeding season to produce a replacement. And because the top predators we target naturally don’t face much predation themselves, they have not evolved ways to successfully avoid humans or reproduce fast enough to make up for human-induced losses.

Learning from them

The study also suggests that there’s hope for bringing declining populations back from the brink—if we learn to act more like the predatory animals we’ve been harvesting. That means sparing the adults and going after the young, and lowering our fish catch rates.

For example, some nets allow fisheries to define the entrance size, very easily allowing the exclusion of larger fish, the ones best left to reproduce. Fishing quotas could be readjusted to more closely align with the numbers taken by natural predators. Instead of allowing trophy hunting of large, land carnivores, countries could promote the just-as-lucrative business of wildlife ecotourism. According to Jeff Flocken, North American Regional Director of the International Fund for Animal Welfare, in Africa legal trophy hunting is measured by the millions it contributes to the economy, while nonlethal nature viewing is measured by the billions. Nature tourism generates 13 to 15 times more revenue than trophy hunting.

Could we ever go back to acting like normal predators? ©Justin R. Gibson

Could we ever go back to acting like normal predators? ©Justin R. Gibson

Some say, however, that these tactics would never work. Ray Hilborn, a professor in the School of Aquatic and Fishery Sciences at the University of Washington, Seattle, and an expert on sustainable exploitation, says that even though humans may take more fish than any one predator, our haul makes up only 40 percent of the total natural predation on fish—a reasonable amount given the need to provide food for the human population. He doesn’t believe that we can fish less and still supply enough food for the world. In Asia alone about 300 million people rely on fish as their primary source of protein. With continued population growth around the world, those numbers will only increase.

And given that the biggest fish earn the biggest bucks, focusing on juveniles would yield less money per ton of fish caught—something fisheries most likely wouldn’t support. Furthermore, quotas would have to be dramatically reduced to bring them closer to fish-predation rates from nonhuman predators.

Whether or not you believe with the study’s hopeful conclusions, it’s clear that we would need significant cultural, economic and institutional changes in order to limit human predation and bring our rate of killing more in line with the rate at which natural predators harvest prey if some species of wildlife are to survive.

Do you think it’s possible that we superpredators could go back to acting more like normal predators? Is an overhaul of the systems we use to relate to the animals we eat and hunt even possible?

Here’s to finding your true places and natural habitats,

Candy

15 Comments »

  1. Alejandra Méndez November 7, 2015 at 6:03 pm - Reply

    Chain food. It is a hard problem. If you consider that there are humans inside starvation. Human none equilibrium will modify animal equilibrium.

  2. Jonathan Nahum November 7, 2015 at 6:02 pm - Reply

    I believe that a solution to our problem as dominating top predators can only be economical and sustainable. for example in the case of over fishing, I think much more money and effort should be put into growing fish in closed systems and research how to do it. in that way we would control every detail of raising this fish and stop depleting our oceans…

  3. Susan Thompson November 7, 2015 at 6:01 pm - Reply

    My view is that we are animals too, and we are part of the food chain. Our intelligence has over come many of our competition in the animal world. We all evolve to our environment, of which we have no control. Our environment will evolve, as to mans impact on it. This becoming mans new enemy, and new competitor.

  4. James Crants November 7, 2015 at 6:00 pm - Reply

    It’s interesting, though, that beyond how many of us there are and how much meat we consume per capita, the kinds of individual animals we choose to eat increases our impact further.

  5. Saskiya Richards November 7, 2015 at 5:59 pm - Reply

    No surprise there, the earth’s population is out of control and, in a nut shell, there simply are the resources available and due to the rapid increase in medical science and technology this has backfired on us.

  6. James Crants October 24, 2015 at 1:36 pm - Reply

    Actually, we _are_ at the top of the food chain. We have the power to put ourselves there, and we have. The challenge is convincing each other that we have a moral and ethical obligation to check our collective ego and respect and preserve all these species and ecosystems we have the power to destroy. And I do think we have to appeal to ethics and morality, as well as self-interest. Yes, it’s in our selfish interest not to destroy everything we depend on, and better that we figure that out before we’ve destroyed so much that we end up battling each other on a global scale over the scraps. But only a sense of moral and ethical obligation to conserve can lead us to do better than merely clearing the relatively low bar of avoiding an environmental apocalypse. Indeed, considering how the political debate over global warming has been going, even avoiding an environmental apocalypse may require us agreeing that we should do more than the minimum required to avert an environmental apocalypse. We’re apparently too short-sighted to recognize a looming disaster before it hits us full-on.

  7. Mohamed El hashemy October 19, 2015 at 7:25 am - Reply

    The Protected areas may be a reason to reduce the harm to the animals.

  8. Alejandro Camacho October 18, 2015 at 9:15 am - Reply

    I agree C. Andrews partcularly in the case of fisheries, but if we compare the impact of habitat reduction for wildlife. this will be far more important . Yes, we should change the way we relate to widlife but first we most protect their habitat.

  9. Petra Mihalic October 16, 2015 at 1:00 pm - Reply

    I try to stay an optimist when it comes to making a shift in human mind and embracing sustainable consumption but not much evidence justifying my attitude can be found. Animals provide life and we are completely dependant upon them; it doesn’t take to be a scientist to understand this notion but sadly people are good at ignoring facts. Humans are the only animals completely unable to survive in the wild on their own and yet we prey on animals like it is the other way around.
    And yes we better be a Super-custodians as we do not have 10 other planets to settle in…

  10. Atul Shyoran October 15, 2015 at 6:54 am - Reply

    yes we can..!!

  11. Yvonne Winter October 14, 2015 at 4:47 pm - Reply

    The ego of mankind must change on a global scale to realise, accept and adapt to the fact that we are not at the top of the food chain. The Earth and the services it provides to us freely must be respected and not abused. This is the only hope we have. *sigh*

  12. Carol Patterson October 14, 2015 at 4:34 pm - Reply

    The people living near Waterton Lakes National Park have some creative ways to co-exist with large predators. You can read more at http://www.bbc.com/travel/story/20150921-the-man-who-inspired-charles-darwin

  13. Capt. Richard Barone October 14, 2015 at 11:36 am - Reply

    We are actually the super predated in many ways as well and manipulated in general to destroy the earth and act worse than animals, this however is changing as we alter and expand our definitions and language, we are the Super-custodians.

  14. Laura Igoe October 14, 2015 at 11:32 am - Reply

    This is a very interesting way to see how we impact the food web. I think it shows how we tend to forget that we are within the system of nature–not outside of it–and therefore affect it.

  15. Laurie Rosenberg October 13, 2015 at 11:46 am - Reply

    Been re-reading Aldo Leopold’s “Thinking Like A Mountain” and this brings it home once again! Thanks for posting!

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