Extreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016

Abstract

About 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. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Threequarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. 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. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016-2017) the mass mortality event. 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. These events cooccurred 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. Other studies PLOS ONE | https://doi.org/10.1371/journal.pone.0226087 January 15, 2020 1 / 32 OPEN ACCESS Citation: Piatt JF, Parrish JK, Renner HM, Schoen SK, Jones TT, Arimitsu ML, et al. (2020) Extreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016. PLoS ONE 15(1):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. In response, forage fish quality and quantity diminished. Similarly, large ectothermic groundfish were thought to have increased their demand for forage fish, resulting in greater top-predator demands for diminished forage fish resources. We hypothesize that these bottom-up and top-down forces created an "ectothermic vise" on forage species leading to their system-wide scarcity and resulting in mass mortality of murres and many other fish, bird and mammal species in the region during 2014-2017.

Marine Heatwave Stress Test of Ecosystem-Based Fisheries Management in the Gulf of Alaska Pacific Cod Fishery

“…Seabirds in the western GOA had good reproductive success in the first year of the heatwave, but showed widespread reproductive failures in 2015 (Renner et al, 2017;Zador and Yasumiishi, 2017). This included common murres, which also experienced a record die-off in the GOA during the winter of 2015-2016 (Piatt et al, 2020). In general, forage fish eating seabird fared poorly during the heatwave, while mixed fish and zooplanktivorous seabird fared better.…”

Global Oceans

“…SB3.1). NCP computed from the nitrate record shows unusually low values in 2015 (Bif et al 2019) that led to an unprecedented ecosystem response including shifts in plankton community composition (Peterson et al 2017), impacts on fisheries (Richerson and Holland 2017), and large-scale mortality in seabirds (Piatt et al 2020).…”

Insights about Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): What Is Tetrabothrius jagerskioeldi jagerskioeldi? ?

“…Perturbations in ecosystem structure and dynamics are manifested in mortality events for zooplanktivorous and piscivorous seabirds through modified phenology for prey, shifts in abundance, and altered patterns of diversity that influence the availability of suitable food resources (e.g., Baduini et al, 2001;Napp and Hunt, 2001;Jones et al, 2019). The greatest sustained or persistent marine heat wave documented to date for the Gulf of Alaska and Bering Sea, during 2016-2017, resulted in extensive breeding failures and an estimated mortality event for over 1 million common murres which represent the dominant marine avian piscivores in these oceanic systems (Piatt et al, 2020). Contemporary conditions in the Bering Sea ecosystem suggest northward shifts in the distribution of primary forage fishes and macrozooplankton tracking a reduction in the range of cold water and low sea surface temperatures.…”