Noninvasive assessment of Orca decline
Using scat-detection dogs and long-term physiological, reproductive, and toxicant monitoring, researchers worked to unravel the mystery of the Salish Sea orcas’ persistent decline.
Samuel Wasser, University of Washington, Department of Biology
Washington Sea Grant-supported researchers developed and validated an innovative, noninvasive, highly efficient system of gathering repeated whale scat samples using boat-borne detection dogs. They used these samples to measure and monitor, over the long term, individual whales’ nutritional, physiological, and reproductive condition, including toxicant levels.
Endangered southern resident killer whales, the Salish Sea’s peak predators, suffer low reproduction, forestalling their recovery. To understand and reverse their decline, researchers and managers must untangle a complex suite of environmental threats: nutritional deficiency amidst declining and erratic salmon runs; vessel disturbance, especially by whale-watching boats; and the toxic exposures that afflict apex predators in impacted waters ringed by urban and industrial centers.
These measurements point strongly to nutrition – specifically, spring Columbia and summer Fraser Chinook salmon runs – as key to the orcas’ recovery. They reveal high rates of pregnancy failure, often mid-gestation when the physiological costs are especially severe, and accelerated releases of persistent organic pollutants from fat tissue in malnourished whales. To save its cherished killer whales, the region must save its salmon. Toward this end, marine detection dogs – particularly the celebrated “Tucker” – proved an enormously successful if incidental outreach vehicle for raising media attention and public concern for the orcas’ plight.
Ayres KL, Booth RK, Hempelmann JA, Koski KL, Emmons CK, Baird RW, Balcomb-Bartok K, Hanson MB, Ford MJ, Wasser SK (2012) Distinguishing the impacts of inadequate prey and vessel traffic on an endangered killer whale (Orcinus orca) population. PLoS One, 7(6):e36842.
Ahearn A (2012) What’s stressing out orcas? Think portion size. EarthFix KUOW.org. June 6.
Wasser SK, Azkarate JC, Booth RK, Hayward L, Hunt K, Ayres K, Vynne C, Gobush K, Canales-Espinosa D, Rodríguez-Luna E (2010) Non-invasive measurement of thyroid hormone in feces of a diverse array of avian and mammalian species. General and Comparative Endocrinology, 168 (1):1-7.