Project Description

Despite the fact that bearded seals (Erignathus barbatus) are one of the most important subsistence resources for the native people of coastal northern and western Alaska, and are key ecological components of arctic marine ecosystems, relatively little is known of their abundance, seasonal distribution, migrations, or foraging behaviors. Ice-associated seal populations may be negatively impacted by offshore oil and gas development as well as by climate change. Our ability to predict impacts, however, is limited by inadequate knowledge of seal population structure and foraging ecology. By working cooperatively with Alaska Native subsistence hunters we will develop methods for live capturing adult bearded seals in the Chukchi Sea and instrumenting them with satellite-linked, data recorders (SDRs). SDRs can provide data on a seal's location, and on the timing and depths of its dives. These data can be analyzed to: 1) provide haul-out correction factors for existing abundance and distribution sightings surveys, 2) assess the seasonal movements and patterns of distribution and diving/foraging behavior, and 3) identify and determine the priority of importance for specific marine habitats associated with key bearded seal life history events such breeding, pup rearing, and foraging and molting.

Issues & Justification

Bearded seals are one of the most important subsistence resources for the native people of coastal northern and western Alaska. Ice-associated seal populations may be negatively impacted by offshore oil and gas development as well as by climate change. However, our ability to predict impacts is limited by inadequate knowledge of seal population structure and foraging ecology. Previous aerial surveys can provide only densities of seals. These densities can not be converted into abundance estimates without information on the proportion of animals hauled out. As adult bearded seals have never been live captured and instrumented with devices for estimating haulout, a reliable estimate for the abundance of the Alaska stock of bearded seals is considered unavailable. Therefore, understanding the timing of haul-out behavior is of critical importance because abundance estimates are needed for developing sound plans for conservation, management, and response to potential environmental impacts of planned oil and gas activities.

Little is known of bearded seal distribution throughout much of the year, however they are known to concentrate in specific areas for breeding and molting; identification of these areas is crucial to the assessment of potential impacts from industrial activities. As inhabitants of the broken pack ice and open water zones, bearded seals are vulnerable to impacts of spilled oil, both from direct contact with oil and from indirect effects through the benthic organisms on which they feed. Although they may be capable of feeding on sympagic (under-ice) and mid-water prey, bearded seals are primarily benthic feeders and are therefore strongly associated with the shallow continental shelf zones that would likely be subject to petroleum exploration and extraction. Any potential industrial impacts on bearded seals could potentially be mitigated or magnified by climatic-induced change in the physical and biological habitat.

Goals

• Estimate the seasonal movements and patterns of distribution and behavior of bearded seals. Emphasis is placed on movements of seals between near-shore areas where they are hunted for subsistence and offshore areas where interactions with fishing and industrial development are possible.
• Identify specific marine habitats associated with key life history events of bearded seals, such as breeding, pup rearing, foraging, and molting, and rank them according to importance of use.
• Improve the accuracy and precision of estimates of bearded seal abundance developing a haul-out correction factor that can be used to adjust existing survey counts for the proportion of seals that are at sea and not observed during aerial surveys.
• To develop a working relationship with the native members of villages along the coastline of arctic and sub-arctic Alaska.

Methods

Satellite telemetry is a powerful tool for addressing many aspects of bearded seal ecology and behavior. We will use SDRs to investigate the marine habitat use, movements, distribution and diving behaviors of adult bearded seals in relation to the impacts of oil and gas exploration activities and potential oil spills, including both the risk of direct exposure to oil and secondary exposure caused by ingestion of prey that have been exposed to oil. We further propose to examine the haul-out patterns of bearded seals to create correction factors for existing aerial abundance surveys. Finally, we will collaborate with other researchers and organizations to obtain outside support for the analysis of tissue samples collected during capture activities to assess nutritional status, health, contaminant load, and population structure.