HELENA, Mont. — After 42 years on the endangered species list, the Yellowstone grizzly bear — whose numbers have grown to more than 700 from fewer than 150 — will lose its protected status, the Interior Department announced on Thursday.

The move has long been debated, despite the bear’s increasing population in areas where it had not been seen in decades. The Fish and Wildlife Service tried to delist the bear in 2007 but was ordered by federal court decisions to reconsider because of a decline in white bark pine, an important bear food source decimated by insects as the region’s temperatures have risen.

In deciding to lift the protection, Ryan Zinke, the secretary of the interior, remarked on the long-term efforts that have allowed the bear to thrive: “This achievement stands as one of America’s great conservation successes; the culmination of decades of hard work and dedication on the part of state, tribal, federal and private partners,” Mr. Zinke said in a statement. “As a Montanan, I’m proud of what we’ve achieved together.”

The action will not affect the protected status of the other major population of grizzlies in the lower 48 states, those that live in and around Glacier National Park of Montana, which number about 1,000. However, experts say this population, too, could soon be delisted. Several small, isolated populations would remain protected.