Scientists have reported a devastating biological disaster. A concentrated marine heat wave in the Pacific Ocean between 2013 and 2016 called the ‘Blob’ was responsible for almost a million common murres amongst other wildlife making it the largest sea bird death in recorded history.
The estimates are based on some 62,000 murres that were washed up ashore on the west coast of the US during 2015 and 2016 covering the area from California to Alaska. Only a small number of birds that die at sea wash up on shore showing that the actual number of dead birds was much higher than the bodies found.
"Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often," says biologist Julia Parrish, from the University of Washington.
"We believe that the smoking gun for common Murres – beyond the marine heat wave itself – was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators likes walleye, Pollock and Pacific cod greatly increased."
A team of scientists reviewed the fish and plankton collected by fisheries during the time the ‘Blob’ was reported at its peak concluding that the warmer temperatures in waters had increased the metabolism of the ocean dwellers. It meant that the predatory fish would be eating more than usual causing pressure at the top of the food chain. It would have made the forage fish that murres survive on, very hard to find. Murres feed on small forage fish like herring, sardines, anchovies, and salmon and the effects of the ‘Blob’ made it hard to survive.
"Food demands of large commercial ground fish like cod, Pollock, halibut and hake were predicted to increase dramatically with the level of the warming observed with the blob," says biologist John Piatt, from the US Geological Survey's Alaska Science Center.