You learn quickly here that not all fish are the same. There are several different kinds of salmon, and even within species--like chinook salmon--there are different runs, like spring chinook and fall chinook. Then there are physically isolated populations of fish, like the redband trout of the upper McCloud River on the California side.
Recent research proves the McCloud River Redband Trout is a distinct subspecies of redband trout, genetically different from other redband trout. Matthew Campbell led the team that did the research, out of the University of California-Davis. He talks to us about the process, down to the molecular level, to prove the point.