Seabird and Mammal Surveys Off California, Oregon, and Washington

By Jonathan Felis, Josh Adams, and John Takekawa Mar. / Apr. 2012

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Scientists from the U.S. Geological Survey (USGS) Western Ecological Research Center are conducting new seabird and marine mammal surveys for the Bureau of Ocean Energy Management (BOEM) in its Pacific Outer Continental Shelf Region. Their findings will inform future alternative-energy planning, development, and management in the northern California Current System—a biologically rich oceanic region offshore western North America dominated by the southward-meandering California Current.

Above: Survey aircraft (Partenavia P-68) being loaded for departure. Inset shows observers in back seat counting seabirds in flight. [larger version]

The survey project, called the Pacific Continental Shelf Environmental Assessment (PaCSEA), is the first set of comprehensive, multiseasonal aerial surveys in the region since similar surveys were conducted two decades ago. The primary survey area extends from Grays Harbor, Washington (approximately 47° N. latitude), to Fort Bragg, California (approximately 39° N. latitude; see map).

Above: Map of seabird and marine-mammal survey transect lines (red) over continental shelf and slope waters in California, Oregon, and Washington. Index map shows location of study area and generalized path of the California Current, which moves south along the western coast of North America, from the vicinity of Vancouver Island, Canada, to southern Baja California, Mexico. [larger version]

Surveys are being completed from a small fixed-wing, twin-engine plane at low altitude (200 ft above sea level). A navigator sits up front with the pilot to direct the aircraft to transect lines, operate oceanographic remote-sensing equipment, and sight marine mammals. The navigator helps the pilot avoid flying directly over marine mammals, in accordance with National Marine Fisheries Service regulations. Two additional, dedicated observers sit in the rear and count all seabirds and mammals sighted along a fixed-width strip as the plane flies over the ocean.

Collecting remotely sensed oceanographic data simultaneously with seabird and mammal counts will enable project scientists to examine the relations between ocean features—such as water masses of differing temperature—and the distribution of birds and mammals. The scientists are using an onboard pyrometer—a remote-sensing instrument that intercepts and measures thermal radiation—to measure sea-surface temperature, and a hyperspectral radiometer—a device that measures the power of electromagnetic radiation over a broad range of wavelengths—to measure sea-surface radiance and reflectance. Hyperspectral radiometry data can provide information about chlorophyll, phytoplankton, dissolved organic matter, and other constituents of the seawater. In the northern California Current System, seasonal upwelling and the Columbia River plume create oceanographic structure, including areas of enhanced phytoplankton growth and water-mass boundaries that can aggregate prey near the surface, thereby increasing availability for predators. The on-board remote-sensing equipment allows the researchers to map such oceanographic structures at fine scales and relate them to the observed patterns of seabird and mammal abundance.

Surveys were conducted in January, June, and October of 2011 and February of 2012; additional surveys are scheduled for May, July, and September of 2012. If you would like additional information about PaCSEA, please contact Josh Adams (http://www.werc.usgs.gov/adams).

A selection of photographic highlights from the project thus far is featured below (all photographs by Jonathan Felis, USGS).

Above: Mixed-species flocks of seabirds feed on subsurface aggregations of forage fish and krill along the Oregon coast in October 2011. The flocks pictured here contain mostly Western Gulls (Larus occidentalis) and Common Murres (Uria aalge). [larger version of top photo] [larger version of bottom photo]

Above: A megaherd of approximately 1,000 dolphins travels offshore of Fort Bragg, California, in February 2012. Photographs show only part of the group, which consisted primarily of Pacific White-sided Dolphins (Lagenorhynchus obliquidens), as well as a few Northern Right Whale Dolphins (Lissodelphis borealis). [larger version of top photo] [larger version of bottom photo]

Above: Two of the biggest animals on Earth, the Blue Whale (Balaenoptera musculus; top) and Fin Whale (Balaenoptera physalus; bottom) have been sighted infrequently during surveys. [larger version of top photo] [larger version of bottom photo]

Above: This photograph shows a mixed cetacean-seabird foraging aggregation off northern Oregon in June 2011. A feeding Humpback Whale (Megaptera novaeangliae) is surrounded by Pacific White-sided Dolphins and flocking Sooty Shearwaters (Puffinus griseus). Move your cursor over the photo to see a duplicate photograph that was desaturated (color intensity reduced) to more clearly reveal the presence of the shearwaters and dolphins. [larger version]

Seabirds off Southern California—Surveys Reveal Patterns in Abundance and Distribution November 2004

Western Ecological Research Center (WERC) USGS

Josh Adams, Seabird Ecologist USGS

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