NOAA Fisheries and the Washington Department of Fish and Wildlife have partnered to produce a list of the west coast Chinook salmon stocks most important to the whale’s survival. This list comes as a part of a special action plan by NOAA to address the three primary threats to the southern resident killer whales: Chemical contaminants, vessel traffic, and lack of prey. The salmon, themselves endangered, are the preferred food source for the whales, and identifying the salmon runs—which include Sacramento River and San Joaquin River runs—that most overlap with the range of the southern residents could be crucial to their eventual recovery. “Those fish support not only the commercial fishery but the whales that migrate north after they leave the Golden Gate,” says Michael Milstein of the National Marine Fisheries Service. “We know [orcas] are highly intelligent and they may be handing down information through generations as to where to look for salmon.” In July, marine biologists across the world watched in fascination–and heartbreak–as a female southern resident killer whale refused to abandon her newborn calf for days after it had perished, probably as a result of the mother’s malnutrition. “These whales are truly a ‘West Coast’ population,” Milstein explains. “It’s not about any one stock being more important than the others, but rather the whole range providing them with variety as they travel through areas where they have historically found plenty.”