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 1999–2002, 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 Game (CDFG; now CA Department of Fish and Wildlife, CADFW) and U.S. Navy also provided significant matching funds. Oceanographic Context - USGS-HSU surveys began in May 1999, immediately following the strong 1997–1998 El Niño event. The 1999–2002 period featured a series of cold-water, La Niña 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 Niña 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 Niñas often follow El Niños, 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 1975–1983, coincident with another climate shift—from cold to warm conditions throughout the CCS (Mantua et al. 1997). Briggs et al. surveyed north of Point Conception during 1980–1983, 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

Tracklines and associated observations were mapped and analyzed using ArcMap (ESRI, Redlands, CA). GPS data were recorded in NAD27 map datum and projected to an USGS Albers Equal Area Conic map projection for presentation and subsequent density analyses. Concatenated GPS and observation data were then used to generate point and line coverages in ArcMap (ESRI, Redlands, CA). We designed a custom analytic tool using ArcMap Model Builder that allows for the construction and export of user-specified and effort-adjusted spatial binning of species observations along continuous trackines. For the purposes of this report, we calculated seabird density estimates and marine mammal counts along continuous 3.0-kilometer and 7.7-kilometer trackline segments (i.e., 3.0 kilometer and 7.7 kilometer bins). Therefore, marine bird densities (at 3-kilometer scale, for example) are based on a composite strip area ranging from 0.15 per kilometer squared (one observer on effort) to 0.30 per kilometer squared (two observers on effort). We made no effort to adjust densities such that they would be proportional to variations in the area of buffered transect strip bin (i.e., weighted offset variable). 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. References- ESRI. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute.

Tracklines and associated observations were mapped and analyzed using ArcMap (ESRI, Redlands, CA). GPS data were recorded in NAD27 map datum and projected to an USGS Albers Equal Area Conic map projection for presentation and subsequent density analyses. Concatenated GPS and observation data were then used to generate point and line coverages in ArcMap (ESRI, Redlands, CA). We designed a custom analytic tool using ArcMap Model Builder that allows for the construction and export of user-specified and effort-adjusted spatial binning of species observations along continuous trackines. For the purposes of this report, we calculated seabird density estimates and marine mammal counts along continuous 3.0-kilometer and 7.7-kilometer trackline segments (i.e., 3.0 kilometer and 7.7 kilometer bins). Therefore, marine bird densities (at 3-kilometer scale, for example) are based on a composite strip area ranging from 0.15 per kilometer squared (one observer on effort) to 0.30 per kilometer squared (two observers on effort). We made no effort to adjust densities such that they would be proportional to variations in the area of buffered transect strip bin (i.e., weighted offset variable). 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. References- ESRI. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute.

Tracklines and associated observations were mapped and analyzed using ArcMap (ESRI, Redlands, CA). GPS data were recorded in NAD27 map datum and projected to an USGS Albers Equal Area Conic map projection for presentation and subsequent density analyses. Concatenated GPS and observation data were then used to generate point and line coverages in ArcMap (ESRI, Redlands, CA). We designed a custom analytic tool using ArcMap Model Builder that allows for the construction and export of user-specified and effort-adjusted spatial binning of species observations along continuous trackines. For the purposes of this report, we calculated seabird density estimates and marine mammal counts along continuous 3.0-kilometer and 7.7-kilometer trackline segments (i.e., 3.0 kilometer and 7.7 kilometer bins). Therefore, marine bird densities (at 3-kilometer scale, for example) are based on a composite strip area ranging from 0.15 per kilometer squared (one observer on effort) to 0.30 per kilometer squared (two observers on effort). We made no effort to adjust densities such that they would be proportional to variations in the area of buffered transect strip bin (i.e., weighted offset variable). 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. References- ESRI. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute.

Tracklines and associated observations were mapped and analyzed using ArcMap (ESRI, Redlands, CA). GPS data were recorded in NAD27 map datum and projected to an USGS Albers Equal Area Conic map projection for presentation and subsequent density analyses. Concatenated GPS and observation data were then used to generate point and line coverages in ArcMap (ESRI, Redlands, CA). We designed a custom analytic tool using ArcMap Model Builder that allows for the construction and export of user-specified and effort-adjusted spatial binning of species observations along continuous trackines. For the purposes of this report, we calculated seabird density estimates and marine mammal counts along continuous 3.0-kilometer and 7.7-kilometer trackline segments (i.e., 3.0 kilometer and 7.7 kilometer bins). Therefore, marine bird densities (at 3-kilometer scale, for example) are based on a composite strip area ranging from 0.15 per kilometer squared (one observer on effort) to 0.30 per kilometer squared (two observers on effort). We made no effort to adjust densities such that they would be proportional to variations in the area of buffered transect strip bin (i.e., weighted offset variable). 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. References- ESRI. ArcGIS Desktop: Release 10. Redlands, CA: Environmental Systems Research Institute.

Broad survey lines, island radial survey lines, coastal survey lines, and focal-area (Santa Barbara Channel) survey lines were surveyed during each oceanographic season: spring (May), fall (September), and winter (January) during 1999 (May and September), 2000 (January, May, September), 2001 (January May, September), and 2002 (January). Aerial survey methods follow Mason et al. (2007). Specifically, we recorded all sightings of marine animals, vessels, and floating objects from twin-engine, high wing aircraft (Partenavia P-68s, Aspen Helicopters, Oxnard, CA, or California Department of Fish and Game) along pre-determined 100-meter (50 meters per side) strip transects at 60 meters above sea level. Surveys were flown at 160 kilometers per hour, and we used a Global Positioning System (GPS) unit linked to a laptop computer that allowed us to simultaneously collect coordinates (WGS-84 map datum), sea surface temperature (SST, degrees Celcius [°C]) determined via a belly-mounted, digital infrared radiation pyrometer (Heitronics™ KT19.85; measurement interval = 1 s, response time = 3 ms, emissivity = 0.99). SST values were appended to GPS flight data based on date and time. During individual surveys, observers frequently verified strip widths using hand-held clinometers. Observations generally were discontinued when glare exceeded greater than 25% of the field-of-view or if sea state exceeded Beaufort 5 (29–38 kilometers per hour wind speed). Observations were recorded into hand-held audio recorders. The third (non-dedicated) observer assisted the pilot with navigation, monitored sensor data, and maintained the onboard computer. The third observer also recorded incidental observations of marine mammals outside transects (i.e., non-standardized effort sightings). The effort for incidental marine mammal observations is not always consistent because the third observer was sometimes required to be engaged in other activities. Observations of species or individuals identified to nearest taxon included number of individuals, time, pre-coded behaviors, flight direction, and interspecies or vessel associations. Digital recordings of observations were archived and used by observers after surveys to enter data into a customized Graphical User Interface. Observation data were proofed after transcription to ensure accuracy or to resolve inconsistencies. Species observations were linked with GPS-based tracklines generated at 1 to 3 s intervals. Based on variations in the lag-time between sightings and recordings, we estimate that observations have a nominal along-trackline spatial accuracy of 222 meters, based on a five-second lag at 160 kilometers per hour survey speed. 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.

Broad survey lines, island radial survey lines, coastal survey lines, and focal-area (Santa Barbara Channel) survey lines were surveyed during each oceanographic season: spring (May), fall (September), and winter (January) during 1999 (May and September), 2000 (January, May, September), 2001 (January May, September), and 2002 (January). Aerial survey methods follow Mason et al. (2007). Specifically, we recorded all sightings of marine animals, vessels, and floating objects from twin-engine, high wing aircraft (Partenavia P-68s, Aspen Helicopters, Oxnard, CA, or California Department of Fish and Game) along pre-determined 100-meter (50 meters per side) strip transects at 60 meters above sea level. Surveys were flown at 160 kilometers per hour, and we used a Global Positioning System (GPS) unit linked to a laptop computer that allowed us to simultaneously collect coordinates (WGS-84 map datum), sea surface temperature (SST, degrees Celcius [°C]) determined via a belly-mounted, digital infrared radiation pyrometer (Heitronics™ KT19.85; measurement interval = 1 s, response time = 3 ms, emissivity = 0.99). SST values were appended to GPS flight data based on date and time. During individual surveys, observers frequently verified strip widths using hand-held clinometers. Observations generally were discontinued when glare exceeded greater than 25% of the field-of-view or if sea state exceeded Beaufort 5 (29–38 kilometers per hour wind speed). Observations were recorded into hand-held audio recorders. The third (non-dedicated) observer assisted the pilot with navigation, monitored sensor data, and maintained the onboard computer. The third observer also recorded incidental observations of marine mammals outside transects (i.e., non-standardized effort sightings). The effort for incidental marine mammal observations is not always consistent because the third observer was sometimes required to be engaged in other activities. Observations of species or individuals identified to nearest taxon included number of individuals, time, pre-coded behaviors, flight direction, and interspecies or vessel associations. Digital recordings of observations were archived and used by observers after surveys to enter data into a customized Graphical User Interface. Observation data were proofed after transcription to ensure accuracy or to resolve inconsistencies. Species observations were linked with GPS-based tracklines generated at 1 to 3 s intervals. Based on variations in the lag-time between sightings and recordings, we estimate that observations have a nominal along-trackline spatial accuracy of 222 meters, based on a five-second lag at 160 kilometers per hour survey speed. 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.

This database is a compilation of marine mammal and seabird information collected along the Pacific coast of the United States and U.S. territories in the Pacific from surveys that were solicited among regional research communities and persons. Information from standardized surveys was gathered from 2015 to 2018 and includes programs and researchers who collected information regarding seabirds since 1960.

This database is a compilation of marine mammal and seabird information collected along the Pacific coast of the United States and U.S. territories in the Pacific from surveys that were solicited among regional research communities and persons. Information from standardized surveys was gathered from 2015 to 2018 and includes programs and researchers who collected information regarding seabirds since 1960.

Seabirds are long-lived, upper trophic level predators that are integral components of marine ecosystems. During the breeding season, seabirds are central place foragers and must return to their nests to incubate eggs and provision young throughout the day. As such, they have limited foraging ranges during that time and will benefit from protected areas within these ranges. Marine protected areas (MPAs) can provide both direct and indirect benefits to seabirds. Direct benefits involve reducing the direct interactions seabirds have with humans like incidental take and gear entanglement as well as human- caused disturbance to breeding and roosting sites. Indirect benefits involve reducing competition with humans for prey resources. Many coastally breeding seabirds rely on juvenile age classes of fished species. Decreases in adult fish catch can lead to increased spawning biomass and, thus, more seabird prey. Herein, we summarize the results of baseline seabird monitoring within the South Coast Study Region (SCSR) of California’s Marine Life Protection Act (MLPA) Initiative in 2012-2013. The long-term objectives of our monitoring are to 1) document how seabirds are using coastal and nearshore habitats in relation to newly established MPAs and 2) develop seabirds as indicators to study the processes (e.g., recruitment) impacting change resulting from MPA establishment, including changes in nearshore fish and invertebrate populations and human use patterns that can impact seabirds. Funding for baseline monitoring was provided by SeaGrant, Project Number R/MPA-28 (Grant No. MPA 10-049).