Multi-Decadal Assessment of Heavy Metals in Subsistence-Harvested Alaska Pinniped

Grant Winners

Dean

Abstract

The coastal, indigenous communities around Alaska have subsisted on marine organisms for generations, often focusing on large apex predators such as seals, sea lions, and whales. Three species of pinnipeds (harbor seal, Steller sea lion, northern fur seal) and the northern sea otter have all undergone significant population declines since the 1970s, some regions more than others. Heavy metal concentrations in their tissues via diet and, subsequently in human tissues, can have detrimental effects. Archived vibrissae (whiskers) and organ tissues from these four species from the Bering Sea and throughout the Gulf of Alaska, 1993 to 2014, are in the possession of the project investigators. These tissues represent animals that were all subsistence harvested and had stable isotope analyses (δ13C and δ15N) performed to assess trophic position at various geographic locations. Vibrissae continuously grow and provide a timeline of what and where the animals have been eating. This is particularly important as each of the pinnipeds/fissipeds have different migratory or movement patterns; therefore, the animals' tissues record the general location of harmful metals. Tissues from these species are exceedingly difficult to obtain; thus, the archived tissues provide a finite and irreplaceable data resource. Whiskers are comprised of keratin, much like fur and hair, which has been proven to record heavy metals. Preliminary analysis confirms successful acquisition of a suite of heavy metals along the vibrissa of each of the four species. Analysis of archived organ tissues, ranging from muscle and blubber to kidney, liver, and brain, will also indicate which tissues, if any, bioaccumulate the metals more readily. The results of this research will not only provide additional data to help with the question of the pinniped and fissiped population declines, but will also be shared with the subsistence communities regarding the level of safety in digesting various marine mammal tissues.