![]() ![]() In response, forage fish quality and quantity diminished. Other studies indicate that this prolonged heatwave reduced phytoplankton biomass and restructured zooplankton communities in favor of lower-calorie species, while it simultaneously increased metabolically driven food demands of ectothermic forage fish. These events co-occurred with the most powerful marine heatwave on record that persisted through 2014–2016 and created an enormous volume of ocean water (the “Blob”) from California to Alaska with temperatures that exceeded average by 2–3 standard deviations. Die-offs and breeding failures occur sporadically in murres, but the magnitude, duration and spatial extent of this die-off, associated with multi-colony and multi-year reproductive failures, is unprecedented and astonishing. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016–2017) the mass mortality event. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Studies show that only a fraction of birds that die at sea typically wash ashore, and we estimate that total mortality approached 1 million birds. Three-quarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. ![]() Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Extreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016 AbstractĪbout 62,000 dead or dying common murres ( Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska. ![]()
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