Two major marine wildlife ecosystems off the west coast of the U.S. and Canada have been affected by the Pacific’s warming waters, said John Piatt, a research wildlife biologist for the U.S. Geological Survey. And he points to the common murres as an indicator of the regions’ health, reports CTV News.
“If tens of thousands of them are dying, it’s because there’s no fish out there, anywhere, over a very large area,” Piatt said. Two sizable marine ecosystems being impacted and this is quite extraordinary, he added.
Piatt blames an upsurge in the number of Alaska’s murre deaths from starvation in December 2015 to some vicious Gulf of Alaska winter storms that hit, one after the other. Overall, though, seabird populations have been well-documented, with data on more than 500 populations around the world collected, dating back to 1950.
Digital Journal reported that Michelle Paleczny, with the University of British Columbia and the Sea Around Us Project, says, “Seabirds are particularly good indicators of the health of marine ecosystems. When we see this magnitude of seabird decline, we can see there is something wrong with marine ecosystems.”
The common murre as an ecosystem health indicator species
The common murre, Uria aalge, is a large auk and is related to the gulls and terns. The murre sort of looks like a penguin. Murre populations are distributed over the polar region from the low-Arctic and boreal waters in the North Atlantic and North Pacific. It spends most of its time at sea, only coming to land to breed on rocky cliff shores or islands.
Murres can easily fly at speeds up to 50 miles per hour and will fly for miles in search of the finger-length fish they eat, diving to depths of 30–60 meters (98–197 feet) and swimming under water up to 100 feet in pursuit of their meal, using their wings for propulsion. A few have been recorded as diving to depths of 180 meters (590 feet), although this is unusual.
Because of the murre’s high metabolism rate, they must eat a lot, needing to match 10 to 30 percent of their body weight daily. It only takes them three days without food to use up their body fat and drop to the threshold that signals starvation. Common murres are known to eat small forage fish: capelin, from the smelt family, and juvenile pollock.
In the summer of 2015, surveys conducted by the National Marine Fisheries Service found both the smelt and pollock were largely absent. And the common murre paid a sad price for the absence of these fish stocks. Last year, volunteers and researchers collected the carcasses of 46,000 dead murres in Alaska and another 6,000 in California, Oregon, and Washington.
Many more carcasses were missed, resulting in a conservative estimate of about 500,000 murres that starved to death. The rising temperatures in the upper 300-foot water column in the Pacific have also been well-documented. Since 2014, the temperature recorded in the upper water column reached 4.5 degrees Fahrenheit higher than normal, due mainly to what a University of Washington meteorologist dubbed “the Blob.”
“Forage fish feed on zooplankton, and cold water produces the biggest, fattiest versions,” said Shannon Atkinson, a physiologist, and researcher at the University of Alaska Fairbanks. This means there isn’t that much zooplankton available and this affects the whole food chain, according to ABC News.
“The dominant food for big North Pacific fish such as halibut, cod, pollock and arrowtooth flounder is,— get ready — juvenile pollock, capelin, sand lance,” Piatt said. “These fish are in direct competition with the birds now, and typically in most of these northern ecosystems, the large, predatory fish eat an order of magnitude more of those forage prey than the birds and mammals combined.”
Piatt is certain that Pacific warmth was the reason behind the huge number of murre deaths. “They died of starvation because there was no food,” he said. “There was no food because there was no fish. And there was no fish because these warm waters did something to them.”
