PROJECT

Background

Of the seabirds that overwinter in Prince William Sound (PWS), nine species were initially injured by the Exxon Valdez oil spill, including three species that have not yet recovered or recovery status is unknown (pigeon guillemot, marbled murrelet, Kittlitz’s murrelet). The majority of seabird monitoring in areas impacted by the spill has occurred during the breeding season when food is relatively abundant. However, the non-breeding season may be a critical period for seabird survival as food tends to be relatively scarce or inaccessible, the climate more extreme, light levels and day length reduced, and water temperatures cooler. Monitoring marine birds in PWS during winter is needed to understand how post-spill ecosystem recovery and changing physical and biological factors are affecting marine bird abundance and species composition, as well as their distribution and habitat use.

The specific goals of this project are to:

1. Characterize the spatial and temporal distribution of marine birds in PWS during fall and winter.
2. Estimate marine bird abundance and distribution in areas with known seasonally predictable aggregations of predators and prey.
   1. Relate marine bird presence to prey fields identified during concurrent hydroacoustic surveys
   2. Characterize marine bird-humpback whale foraging dynamics
3. Model species abundance in relation to physical and biological variables across time and space.

Methods

We conduct dedicated marine bird surveys in November and March that are replicated across years in order to extend our long term dataset. All surveys follow established U.S. Fish and Wildlife Service protocols. Each fall from 2017-2021, we will participate in an integrated marine predator-prey survey that includes our marine bird surveys together with surveys for humpback whales and forage fish.

What we will learn

This project will provide information on fall and winter ecology of marine bird species injured by the oil spill and will help determine marine bird vulnerability to future perturbations and environmental change.  Our participation in the integrated marine predator-prey surveys will allow us to identify and estimate the forage fish and euphausiid biomass at the same time and in the same locations in which marine birds and humpback whales are feeding.  Because marine birds and whales are important predators of herring and other forage fish, these surveys will provide key data for population models of herring in PWS.

This project is a continuation of fall and winter marine bird surveys begun in 2007 by co-principal investigators Drs. Mary Anne Bishop and Katherine Kuletz. In 2012, this research project became part of the Gulf Watch Alaska Pelagic Component under the direction of Dr. Bishop.

For further information, visit Gulf Watch Alaska’s project summary here.