Research Technical Report

Chronic Oil and Seabirds

Central Coast Marine Bird Health Study: Year 3 (2005-2007)

Nevins, H.M., E.M. Phillips, C. Gibble, and J.T. Harvey (July 2008)

Report to California Department of Fish and Game Office of Spill Prevention and Response. [unpublished report] 41 pp.

ABSTRACT

The Central Coast Marine Bird Health Study (hereafter, Seabird Health Study) enhanced response capabilities during unusual mortality events in support of OSPR oil spill response and established a regional information center for federal, state, and local resource managers for issues regarding marine bird health. During three years of the CDFG-OSPR SSEP sponsored Seabird Health Study, we systematically quantified human-related and natural causes of mortality based on field studies and lab necropsies (2005, n = 157; 2006, n = 302; 2007, n = 390) and found that although natural mortality factors comprised a significant proportion of determined cases (68%), anthropogenic causes of morbidity and mortality such as chronic oiling, trauma, and fishery interactions continue to be considerable (~15%). Nearshore species (grebes, loons, surf scoters) were more frequently impacted by harmful algal blooms compared with offshore species (murres, shearwaters). We characterized the demography of several unusual mortality events increasing the understanding of causes behind seabird wrecks in the area, including those affecting phalaropes, puffins, fulmars and others. In addition to routine necropsies, we examined post-litigation samples from three past oil spill events: 1997 Kure (n = 602), 1999 Stuyvesant (n = 334), and the 2001-02 San Mateo Mystery Spill (n = 169, aka Luckenbach). We found demographic differences among Common Murres collected during these spill events related to the season and phenology of this species. Winter spills affected mainly adults (60 to 63%) and late summer spill affected significantly more chick-rearing males (15:1 sex ratio). These results provide important information to determine appropriate mitigation measures for effective wildlife restoration. We also provided the CDFG- Petroleum Chemistry Lab with 109 oiled feather samples to help identify non-point source spills and aid in OSPR's natural resources damage assessment (NRDA) process.