Fish and Wildlife Conservation Offices (FWCOs) comprise a network of field stations located throughout the nation. Their staffs work with private landowners, tribal, local, and state governments, other federal agencies, and foreign nations to conserve fisheries. Work conducted by FWCOs represents an original charge of the U.S. Fish and Wildlife Service dating to 1871.

Over 300 biologists in 65 offices in 32 states conserve fish and aquatic resources from the Arctic Circle to the Florida Keys. Biologists monitor and control invasive species; protect imperiled species; evaluate native fish stocks and their habitats; and prescribe remedial measures to fix problems. FWCO biologists render technical assistance to tribes; collaborate on fishery restoration with the National Fish Hatchery System; supervise subsistence use by rural Alaskans on federal lands; conduct scientific studies into fishery problems; restore habitat through the National Fish Passage Program and the National Fish Habitat Action Plan; and they collaborate with partners to conserve migratory fishes that cross multiple jurisdictions.

FWCOs employ scientists with diverse specialties in habitat modeling, hydrology, ecology, statistics, physiology, and fish biology. More habitat means more fish, and that is a guiding precept for FWCOs.