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 global 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: Certain species of 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 percent of globally threatened birds are affected 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).
Mammals: 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 primates, whose body parts are highly valued in some parts of the world for traditional medicine.
Amphibians: Members of the amphibian class 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: Wanted for their skins or shells, their eggs, meat, and for the pet trade, reptiles are harvested and traded around the world. 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: At least 75 percent of all known animal species are invertebrates. Insects, oysters, octopus, crayfish, sea stars, scorpions, crabs, and sponges are all kinds of this animal class. 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 worldwide due to heavy fishing pressure. Shells and corals are collected for ornaments and jewelry.
Plants: The Earth's plants are vital to our survival and are the foundation of most ecosystems. People harvest plants for food, medicine, building materials, and raw materials to make 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.
Environmental Protection Agency
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.
National Science Foundation
Wildlife Trade in Southeast Asia, World Wildlife Fund
Kemp’s Ridley turtle, NOAA
Mammal Species Decline in Face of Over-hunting, Habitat Loss, Climate Change, Worldwatch
Invertebrates: the Silent Majority, Smithsonian National Zoo and Conservation Biology Institute
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