Summary:
The APEX project arose as an effort to determine why some seabirds showed no sign of recovery from the Exxon Valdez spill. Such knowledge was seen as essential to undertaking biologically realistic recovery.

The basic hypothesis of APEX, that food limits recovery, appears to have been confirmed by multiple approaches within APEX. Historical data, from long-running sampling of the Gulf of Alaska show a major change in the marine ecosystem associated with increased water temperatures in the late 1970s. This led to a change from capelin and shrimp to flatfish and pollock. Seabird diets reflect this change; capelin and sand lance were replaced by pollock. At-sea studies during APEX show an abundance of pollock offshore, with schooling species such as herring and sand lance inshore. Most seabird foraging has been concentrated inshore on these species. Capelin have been rare and limited to certain areas.

APEX field studies of Black-legged Kittiwake, Marbled Murrelet, and Pigeon Guillemot show they have better reproductive success when consuming schooling species; forage fish availability and breeding success are positively linked. Laboratory studies show seabirds grow better and have heavier masses at fledging when fed schooling species. Nutritional studies show that schooling fish have higher lipid (and energy) levels than do pollock. Finally, models of populations and foraging show that certain colonies contribute disproportionately to the dynamics of a species.

The bottom line is that changes in the marine ecosystem of the Gulf of Alaska led to a low-fat lean cuisine on which seabirds had difficulty raising young. We are still exploring why this shift occurred and the mechanism through which it affects seabirds.

The main implication for management is that recovery will continue to be inhibited as long as present ecological conditions exist. Our studies have identified key colonies and foraging areas that should be protected during future oil spills and during development of infrastructure in Prince William Sound and the Gulf of Alaska.


Project Leader:
D.C. Duffy, University of Hawaii Manoa, Department of Botany, Honolulu HI