Background - Interest in developing alternative sources of renewable energy to reduce dependence on oil has increased in recent years. Some sources of renewable energy being considered will include power generation infrastructure and support activities located within continental shelf waters, and potentially within deeper waters off the U.S. Pacific coast and beyond state waters (i.e., outside three nautical miles). Currently, the Bureau of Ocean Energy Management (BOEM) is considering renewable energy proposals off the coast of Oregon, California, and Hawaii. From 19992002, the U.S. Geological Survey (USGS) and Humboldt State University (HSU) worked with BOEM (formely known as the Minerals Management Service, MMS) to conduct a multi-year study that quantified the at-sea distribution of seabirds and marine mammals. The aerial at-sea survey team flew over 55,000 kilometers and counted 485,000 seabirds (67 species) and 64,000 marine mammals (19 species). The study provided resource managers with updated information on distribution and abundance patterns and compared results with information from the late 1970s to early 1980s (Briggs et al. 1981, Briggs et al. 1987, see Mason et al. 2007). The California Department of Fish and Wildlife (CDFW; formerly known as California Department of Fish and Game, CDFG) and U.S. Navy also provided significant matching funds.
Oceanographic Context - USGS-HSU surveys began in May 1999, immediately following the strong 19971998 El Nio event. The 19992002 period featured a series of cold-water, La Nia events which led some researchers to postulate that the California Current System (CCS) had undergone a fundamental climate shift, on the scale of those documented in the 1920s, mid 1940s, and mid 1970s (Schwing et al. 2002). Generally, La Nia events have corresponded with stronger than normal upwelling in the CCS, and during this period, resulted in the greatest 4-yr mean upwelling index value on record (Schwing et al. 2002). La Nias often follow El Nios, and seabird community composition (i.e., relative species-specific abundances) in any given year off southern California, is subject to variability caused by shifts in distribution among both warm- and cool-water affiliated species (Hyrenbach and Veit 2003). In contrast to the Mason et al. (2007) surveys, Briggs et al. (1987) conducted surveys during 19751983, coincident with another climate shiftfrom cold to warm conditions throughout the CCS (Mantua et al. 1997). Briggs et al. surveyed north of Point Conception during 19801983, after the transition to warmer water conditions occurred in the CCS.
Acknowledgements - This project was funded by BOEM through an Interagency Agreement with the U.S. Geological Survey. The authors of these GIS data require that data users contact them regarding intended use and to assist with understanding limitations and interpretation. Aerial survey fieldwork in 1999-2002 was conducted jointly by the U.S. Geological Survey (Western Ecological Research Center, California: Principal Investigators J.Y, Takekawa and D. Orthmeyer; Key Project Staff: J. Adams, J. Ackerman, W.M. Perry, J.J. Felis, and J.L. Lee) and Humboldt State University (Department of Wildlife, Arcata, California; Principal Investigators: R.T. Golightly and H.R. Carter; Project Leader: G. McChesney; Key Project Staff: J. Mason and W. McIver). Major project cooperators who actively participated in aerial at-sea surveys include the Minerals Management Service (M. Pierson, M. McCrary), California Department of Fish and Wildlife (P. Kelly), and the U.S. Navy (S. Schwartz, T. Keeney). For additional acknowledgments, see Mason et al. (2007).
These data are associated with the following publication: Mason, J.W., McChesney, G.J., McIver, W.R., Carter, H.R., Takekawa, J.Y., Golightly, R.T., Ackerman, J.T., Orthmeyer, D.L., Perry, W.M., Yee, J.L. and Pierson, M.O. 2007. At-sea distribution and abundance of seabirds off southern California: a 20-Year comparison. Cooper Ornithological Society, Studies in Avian Biology Vol. 33.
Briggs, K.T., E.W. Chu, D.B. Lewis, W.B. Tyler, R.L. Pitman, and G.L. Hunt Jr. 1981. Summary of marine mammal and seabird surveys of the Southern California Bight area 19751978. Volume III. Investigators reports. Part III. USDI Bureau of Land Management BLM/YN/SR-81/01-04 (PB81-248197) and University of California, Institute of Marine Sciences, Santa Cruz, CA.
Briggs, K.T., W.B. Tyler, D.B. Lewis, and D.R. Carlson. 1987. Bird communities at sea off California: 19751983. Studies in Avian Biology 11.
Schwing, F.B., T. Murphree, and P.M. Green. 2002. The Northern Oscillation Index (NOI): a new climate index for the northeast Pacific. Progress in Oceanography 53: 115-139.
Hyrenbach, K.D. and R.R. Veit. 2003. Ocean warming and seabird communities of the southern California Current System (198798): response at multiple temporal scales. Deep Sea Research Part II: Topical Studies in Oceanography 50: 2537-2565.
Mantua, N.J., Hare, S.R., Zhang, Y., Wallace, J.M. and Francis, R.C. 1997. A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the American Meteorological Society, 78: 1069-1079.
ESRI. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute.
Mason, J.W., McChesney, G.J., McIver, W.R., Carter, H.R., Takekawa, J.Y., Golightly, R.T., Ackerman, J.T., Orthmeyer, D.L., Perry, W.M., Yee, J.L. and Pierson, M.O. 2007. At-sea distribution and abundance of seabirds off southern California: a 20-Year comparison. Cooper Ornithological Society, Studies in Avian Biology Vol. 33.