U.S. Fish and Wildlife Service FWS

The Fish and Wildlife Service was formed in 1940 by merging the Bureau of Fisheries, founded in 1871 to address declining fish stocks, and the Bureau of Biological Survey, founded in 1885 to study birds and mammals. President Theodore Roosevelt had established the first national wildlife refuge at Pelican Island, Florida, in 1903. The service is led by a Director confirmed by the Senate and reports to the Interior Department's Assistant Secretary for Fish and Wildlife and Parks.

It manages the National Wildlife Refuge System, more than 560 refuges covering tens of millions of acres on land plus vast marine monuments, managed mainly for wildlife but open to hunting, fishing, and birdwatching. It runs national fish hatcheries, enforces laws against wildlife trafficking and the Migratory Bird Treaty Act, and administers the Federal Duck Stamp program and grants to states from taxes on hunting and fishing equipment.

Its most consequential role is administering the Endangered Species Act of 1973 for land and freshwater species, deciding which species to list as threatened or endangered, designating critical habitat, and reviewing federal projects that may affect them, while NOAA Fisheries handles most marine species. Listings and habitat decisions often pit conservation against development, energy, and ranching. In 2025 the administration proposed narrowing the regulatory definition of harm under the act, which would reduce protections for habitat, a change supporters said restored the law's original meaning and critics said would hasten extinctions. The service and NOAA Fisheries finalized the rescission of the regulatory definition of harm in July 2026.