Saving the Killers
The population of chinook salmon in California’s Sacramento River isn’t looking too good. Last year, about 90,000 adult chinook (or king) salmon returned to the Sacramento. (That’s less than half the 2006 total of 277,000 and way less than the 2002 run of over 800,000 fish.)
To predict the number of adult spawners for the next season, scientists count the number of jacks (2-year-old male chinooks) that return to the river. That number is usually around 40,000, but last year only 2,000 jacks returned to the Sacramento.
This is a bummer for salmon and salmon fishermen, but it may be even worse for killer whales. Resident killer whales eat salmon–transient killer whales are the ones who eat seals, sea lions, and other marine mammals. The endangered southern resident population of killer whales is especially fond of chinook salmon. Southern residents spend most of their time in and around Washington’s Puget Sound, but for the last six winters, they’ve visited the California coast. Why the recent interest in Cali? Food. Sparse salmon stocks are likely driving the southern residents south, but scientists fear that this year’s declining numbers of chinook in California may leave the whales hungry.
Unfortunately, this salmon shortage isn’t the only obstacle facing the southern residents. The first major blow to this population came in the 1960s and ’70s when 36 southern resident killer whales were removed from the wild and placed in captivity in zoos and aquariums. In 1976, the Washington State Senate outlawed the capture of killer whales, but the southern resident population was slow to recover since most of the captured animals were young. (The removal of young animals greatly reduces the reproductive potential of the remaining wild population.) Scientists estimate that the population finally returned to its pre-capture size in 1993, but it is still small. As of November 2007, there were 88 southern resident killer whales.
Killer whales–which are actually the world’s largest dolphins–are loaded with contaminants. The level of contaminants in southern residents (including agricultural chemicals like DDT and PCBs, chemicals from pulp and paper mills, and flame retardants) far exceeds the levels believed to cause health problems in other marine mammals. In fact, southern residents are so contaminated that stranded animals are considered toxic waste.
Are the southern residents screwed? Hopefully not. The federal government released a recovery plan for the southern residents last month. In it, NMFS (National Marine Fisheries Service) outlines a strategy to restore salmon habitat, clean up existing pollution, minimize contaminant inputs, reduce the risk of oil spills, and improve response to oil spills by permanently stationing a tug boat at the mouth of Puget Sound. If all goes well, salmon will be abundant, the oceans will be pristine, and the southern residents will live happily ever after.