It cracks me up when a bird or such thought extinct for a hundred years is spotted. It shows the vast wilderness in America. The Delta fish will be just fine. The employees that monitor and worry about such might be out of work.
I have some suspicion that field biologists and their managers can make a rare species an endangered one simply by not looking hard enough. Before being rediscovered, the Florida panther was adamantly said to be extinct by the experts, but as a teen I saw one in the wilds of suburbia in that era and heard of other sightings. Now it is accepted that Florida has a small population of Florida panthers.