The San Francisco Bay-Delta and Sacramento-San Joaquin river system are home to a rare, enormous species of living fossil called the green sturgeon. The ancient fish has survived unchanged for almost 200 million years, but is now at the brink of extinction from overharvesting and rapid habit at change. Among the largest, longest-living fish in freshwater, sturgeon can reach seven feet long, weigh 350 pounds, and survive to be 70.
