As a matter of record, this is not a theoretical question. An official press release was issued by the Federal government in 1977 which addresses such a situation when it arises.
The following is excerpted from this U.S. Department of Interior, Fish and Wildlife Service document permanently found posted in its entirety at http://permanent.access.gpo.gov/websites/fwsgov/news.fws.gov/historic/1977/19771221.pdf.
Discussion about cryptid lake creatures is removed from the quote below as it is not germane to the focus of our interests here.
Are We Ready for “Bigfoot” or the Loch Ness Monster?
Dept. of the Interior, Fish and Wildlife Service news release
December 21, 1977
What if they really did find the Loch Ness monster or the legendary Bigfoot of the Pacific Northwest?
Most scientists doubt that these creatures exist, but thoughts of the discovery of a new species that might be the closest living relative to man, or the possibility of finding a leftover dinosaur, excite the imagination of scientist and nonscientist alike. It also poses another question: Would such a creature be subjected to the same kind of exploitation as the giant movie ape, King Kong?
Scientists generally believe there are still many species of birds and mammals that have not been discovered because they live in remote areas and their populations are limited. After all, the gorilla and giant panda were only legends until the late 19th century when their actual existence was first confirmed by scientists. The komodo dragon, a 10-foot-long lizard, wasn’t known to science until 1912. The coelacanth, a deep-water prehistoric fish, was known only from 65 million-year-old fossils until 1938 when a specimen was caught alive off the Madagascar coast.
Just last year a Navy torpedo recovery vessel dropped a sea anchor into 500 feet of water off Hawaii. But instead of a torpedo, it hauled up a 15-foot representative of a new species of shark. The dead shark, named megamouth after its bathtub-shaped lower jaw, had an enormous, short-snouted head and 484 vestigial teeth.
To be sure, no remains of today’s legendary “monsters” have ever been found. There are no living specimens in zoos or dead ones in museums. Most certainly, many “sightings” of these creatures are exaggerated or misinterpreted reports, and some are downright hoaxes.
But finding a Loch Ness monster or Bigfoot is still a possibility, and the discovery would be one of the most important in modern history. As items of scientific and public interest they would surely command more attention than the moon rocks. Millions of curiosity seekers and thousands of zoologists and anthropologists throughout the world would be eager to “get at” the creatures to examine, protect, capture, or just look at them.
What would the United States Government do?
Keith Schreiner is Associate Director of the U.S. Fish and Wildlife Service. The service is the Government agency with responsibility for protecting endangered and threatened species. Schreiner says “At least, we have the laws and regulations on the books to deal with newly discovered species.”
Schreiner acknowledged, however, that a good deal of international cooperation would be needed if extremely rare species were found abroad. And finding one on U.S. soil would pose serious problems too, Service officials agree.
Undisputed proof of a Bigfoot might cause an immediate, short-term problem no law could handle. Word of its discovery would be flashed around the world within hours, Hysteria, fear, or panic might accompany the news in the area where the creature was located. The throngs of curiosity seekers, would-be captors, and others wishing to find Bigfoot would not only create a serious threat to the animal itself, but to public safety as well. Some officials doubt whether any State or Federal action short of calling out the National Guard could keep order in the area within the first few hours or days of the creature’s discovery. This could be essential until a team of scientists could do the necessary things to ensure the creature’s survival.
The key law in preservation of a species is the Endangered Species Act, which pledges the United States to conserve species of plants and animals facing extinction. This broad, complex law protects endangered species from killing, harassment, and other forms of exploitation. The Act prohibits the import and export of, and interstate commerce in, endangered species. American citizens cannot engage in commercial traffic in endangered species between nations, even when the United States is not involved. Scientists wishing to study endangered species are required to have a permit issued by the U.S. Fish and Wildlife Service.
But before a creature can receive protection under the Endangered Species Act, a number of actions normally must occur which involve recommendations from the public, scientists, and State and foreign governments where the species exists.
The first of these would he the species’ formal description and naming in a recognized scientific publication. In addition, if it were a U.S. species, the Governor of the State where it was found would be contacted, as would the officials of foreign governments if it were found outside the United States. Only after much information was collected could the Service make a formal determination as to whether the species should be afforded endangered or threatened status...
Bigfoot, also known as Sasquatch, is purported to be an 8-foot, 900-pound humanoid that roams the forest and wilderness areas of the Pacific Northwest. One “eyewitness” described an obviously female Sasquatch as a “tall, long-legged, gorilla-like animal covered with dark hair and endowed with a pendulous pair of breasts.” It, too, has been described in publications and given a scientific name. In fact, so many people were stalking Bigfoot with high-powered rifles and cameras that Skamania County, Washington, is prepared to impose a fine of $10,000 and a 5-year jail term on anyone who kills a Bigfoot. The U.S. Army Corps of Engineers even lists Bigfoot as one of the native species in its Environmental Atlas for Washington. This year the Florida and Oregon legislatures also considered bills protecting “Bigfoot” type creatures. A Bureau of Indian Affairs policeman has 18-inch plaster cast footprints of the “McLaughlin monster,” a Bigfoot-type creature he saw last month in South Dakota.
Under U.S. Law, the Secretary of the Interior is empowered to list as threatened or endangered a species for 120 days on an emergency basis. For endangered species in the United States, the Secretary can also designate habitat that is critical to their survival. No Federal agency could then authorize, fund, or carry out any activities which would adversely modify that habitat.
So long-term Federal protection of Nessie or Bigfoot would basically be a matter of following the same regulatory mechanisms already used in protecting whooping cranes and tigers.
“Under normal situations,” Schreiner said, “we must know a great deal about a species before we list it. How big is the population? Does it occur anywhere else? Is the population in danger of decline? Is its habitat secure? Is the species being exploited? What is its reproductive rate? Obviously, if a Bigfoot really were found we could use emergency provisions of the Act to protect it immediately..."