What's worse, by focusing on catching large adults, fishing removes individuals in their reproductive prime that are needed to replenish diminishing populations. Thanks to mechanized fishing, the annual human toll on marine fish may exceed 100 million tons. The researchers report that people catch adult fish at a rate up to 14 times other predators. Because they naturally don't face much predation, they have not evolved ways to successfully avoid humans or reproduce fast enough to make up for human-induced losses.īut the toll on fish is even greater. We kill those carnivores not for food, but for trophies and-sometimes-to eliminate them as competitors, Darimont says. Humans and other predators-like lions, wolves, and grizzly bears-kill wild herbivores at about the same rate, but humans kill large carnivores at nine times the rate of other predators, Darimont, Reimchen, and their colleagues report today in Science. The contrast bothered him, so Reimchen and a few former students searched the scientific literature for data on the rate at which humans and other animals were killing other species.Īfter a decade compiling and analyzing about 300 studies, the team came to some grim conclusions, says Chris Darimont, a conservation scientist also at the University of Victoria who helped lead the study. Yet off that same island, fishermen seemed to be taking a far higher percentage of salmon, mostly adults. Over the decades he determined that each species never kills more than 2% of the sticklebacks per year and usually attacks juveniles. Thomas Reimchen, an evolutionary ecologist at the University of Victoria in Canada, has spent years studying how predators impact the stickleback fish on an island 130 kilometers off the Canadian Pacific coast.
The new study originated in a casual observation. Overfishing is a severe problem in some parts of the world, and a recent report concludes that because of human activity, more than 90 fish species are at risk of extinction. And our hunting technologies have only improved since then, particularly when it comes to catching fish. About 14,000 years ago, humans entering North America caused many large species, such as the mammoth, to disappear. "Any predator capable of exerting such impact will eventually drive its prey to extinction," warns Gerardo Ceballos, an ecologist at the National Autonomous University of Mexico in Mexico City. This superpredator status may fill our bellies, but it has darker implications. Not only do we kill other animals at much higher rates than other predators, but our ability to bring down larger adults can make it very difficult for some prey populations to recover. A new study drives home the destructive power of our species.
0 kommentar(er)
