People have always depended on wildlife and plants for food, clothing, medicine, shelter and many other needs. But today we are taking more than the natural world can supply. The danger is that if we take too many individuals of a species from their natural environment, the species may no longer be able to survive. The loss of one species can affect many other species in an ecosystem.
Overexploitation is the over use of wildlife and plant species by people for food, clothing, pets, medicine, sport and many other purposes.
The hunting, trapping, collecting and fishing of wildlife at unsustainable levels is not something new. The passenger pigeon was hunted to extinction early in the last century, and overhunting nearly caused the extinction of the American bison and several species of whales.
Today, the Endangered Species Act protects some U.S. species that were in danger from overexploitation, and the Convention on International Trade in Endangered Species of Fauna and Flora (CITES) works to prevent the global trade of wildlife. But there are many species that are not protected from being illegally traded or overharvested.
What Wildlife are Being Overexploited?
Fish and other aquatic species
As fishing gear and boats have improved, the fishing industry has become very efficient at harvesting fish and shellfish. The industrialization of the fishing industry and the increasing world demand for seafood have people taking more fish from oceans, lakes and rivers than is sustainable. Prized fish, such as swordfish, cod and tuna, have undergone dramatic declines. In the Great Lakes overfishing has caused whitefish, walleye, and sturgeon populations to decline. Beyond their role in the food supply, freshwater and marine fish are also trapped for the aquarium trade and fished for sport.
Birds are collected or hunted for sport, food and the cage-bird pet trade (parrots and songbirds are prized as pets). Millions of birds are traded internationally each year. Close to 30% of globally threatened birds are threatened by overexploitation, particularly parrots, pigeons and pheasants. The Carolina parakeet was once the only species of parrot in the U.S., but it was hunted to extinction early in the last century for food, to protect crops and for its feathers (which adorned ladies’ hats).
People have always hunted mammal species—for fur, food, sport, and for their horns or antlers. Mammals are also trapped for the pet trade, zoos and biomedical research. Today, illegal hunting still threatens many species, especially large mammals such as tigers, rhinoceros, bears and even primates, whose body parts are highly valued in some parts of the world for traditional medicine.
Amphibians are collected and shipped all over the world for the pet trade, medicine, education (frogs are dissected in many biology classes), scientific research and for food (frog legs are a delicacy in many parts of the world). The California red-legged frog, now a federally protected endangered species, was over hunted for food and its numbers seriously depleted during the Gold Rush in the area around San Francisco.
Reptiles are harvested and traded around the world for their skins or shells, their eggs, meat, and for the pet trade. Overharvesting of the Kemp’s ridley sea turtle’s eggs nearly led to its extinction, and today it is still an endangered species. In the U.S., box turtles are being collected at unsustainable levels for the overseas pet trade. Some reptile skins—such as crocodile, python and monitor lizard—are highly prized as exotic leathers.
Invertebrates make up at least 75% of all known animal species. Insects, oysters, octopus, crayfish, sea stars, scorpions, crabs and sponges are all kinds of invertebrates. Today, many invertebrates—particularly marine invertebrates—are at risk from overharvesting. Chesapeake Bay oysters, once an important part of the Bay economy, are now in decline. Horseshoe crabs, whose eggs provide food for migratory birds, fish and other organisms, are being harvested as bait for eel and whelk fishing. Octopus are suffering declines world-wide due to heavy fishing pressure. Shells and corals are collected for ornaments and jewelry.
Plants are vital to our survival and are the foundation of most of the Earth’s ecosystems. People harvest plants for food, medicine, building materials, and as raw materials for making other products. But we are taking too many plants from the wild. Some plants, such as orchids, are so prized by collectors that they are now endangered and legally protected from poaching by international law. Some medicinal plants, such as American ginseng, have also been so enthusiastically collected that it is now very hard to find them in the wild. A number of tree species that are prized for their wood, such as mahogany, are under threat because of overharvesting.
National Wildlife Magazine Articles:
Rescuing the Reefs
Growing Greener Forests
TRAFFIC, the wildlife trade monitoring network
Selected Endangered, Threatened and Vulnerable Tree Species Traded Internationally
Blue Ocean Institute Online Seafood Guide
Overexploitation of Species (EPA)
Many Species Are Exploited Beyond Sustainable Levels (BirdLife International)
Sustaining Life: How Human Health Depends on Biodiversity. Chivian, Eric and Aaron Bernstein, Eds. Oxford University Press, New York: 2008.
Precious Heritage: The Status of Biodiversity in the United States. Stein, Bruce A., Lynn S. Kutner and Jonathan S. Adams. Oxford University Press, New York: 2000.
Wildlife Trade Threatens Public Health and Ecosystems (NSF)
Vanishing Reptiles (UGA Research)
Wildlife Trade in Southeast Asia (WWF)
Kemp’s ridley turtle (NOAA)
Mammal Species Decline in Face of Over-hunting, Habitat Loss, Climate Change (Worldwatch)
Invertebrates: the Silent Majority (National Zoo)