Dear EarthTalk: What killed all the birds and other sea life last summer on the U.S. west coast?
—Nate McCoury, Bothell, WA
Scientists remain puzzled over what caused such widespread loss of wildlife last summer on the Pacific coast between Northern California and British Columbia. Researchers estimate that more than 100,000 dead seabirds washed ashore, and that as many as 40 percent of the young salmon that normally inhabit the region”s coastal waters that time of year were absent. Meanwhile, other researchers recorded massive die-offs of zooplankton, a keystone of the marine food chain, off the coast of Oregon.
While scientists were perplexed, wildlife watchers were just plain depressed. Some reported seeing birds starve to death on their favorite ocean beaches, while others counted abandoned nests instead of thriving seabird colonies. Beach surveys in May in California found dead birds with emaciated bodies, atrophied muscles and empty stomachs. In Washington, cormorants, normally found dead only occasionally (every 34 miles of beach) were found in substantially larger numbers averaging one every eight-tenths of a mile, according to the Coastal Observation and Seabird Survey Team at the University of Washington. There were also reports of sightings of “emaciated gray whales.”
What scientists do know is that cool winds deviated from their normal northerly course in May, and ocean water temperatures rose two to seven degrees above normal during June. This in turn flushed the nutrients normally available near the ocean surface far below, depriving marine wildlife of the all-you-can-eat buffet they have come to expect during the late spring and early summer.
Whether or not the two scenarios were related is unclear, but some say that global warming is an important factor. Quoted in the Seattle Times, Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration (NOAA) in Newport, Oregon, said, “People have to realize that things are connected—the state of coastal temperatures and plankton populations are connected to larger issues like Pacific salmon populations.”
Nate Mantua, a research scientist with University of Washington’s Climate Impacts Group, says that the odd combination of weather conditions in the summer of 2005 would have to repeat themselves frequently over the next two decades to “lend more weight to the notion that something has changed in coastal climate and that it may be linked to global warming.” That weight may already be building: According to Science Daily, 2005 was already the third consecutive year in which above average ocean temperatures have occurred.
John McGowan of the Scripps Institution of Oceanography in La Jolla, Calif., told the Seattle Post-Intelligencer: “It’s all the way up and down the coast. … There’s a lot of evidence there are important changes going on in the Pacific coast system.” Whatever the cause, scientists are eager to see if such a scenario repeats itself in coming years, and will have their monitoring equipment ready and well tuned.