|Abstract or Summary
- The offshore waters and the coastline of Oregon provide year-round habitat for a number of birds, marine mammals, sea turtles, and possibly bats, at least fifteen of which are federally listed as threatened or endangered. Previous workshops on offshore renewable energy have provided baseline information on the distribution and abundance of these species on the Pacific Outer Continental Shelf (OCS). There are varying amounts of baseline information for offshore species; however, seasonal variability and relative abundance are generally known at a broad scale.
Sea turtles are subtropical and tropical breeders and all species found on the Pacific OCS are uncommon north of Mexico. Sea turtles that occur in the waters off of Oregon are primarily leatherback sea turtles (Dermochelys coriacea); however, loggerhead (Caretta caretta), green (Chelonia mydas), and olive ridley (Lepidochelys olivacea) sea turtles could also occur. All of these species are listed as either threatened or endangered under the federal Endangered Species Act (ESA); there is designated Critical Habitat for the leatherback sea turtle off the Oregon coast. Sea turtles are drawn to offshore waters during the summer upwelling period where they feed on a variety of pelagic and benthic organisms.
A diversity of marine mammals occur offshore of Oregon including 24 species of cetaceans and 6 species of pinnipeds. Sea otters are rare, but stragglers from Washington are occasionally seen along the Oregon coast. Among the cetaceans seen in Oregon waters, the north Pacific right (Eubalaena japonica), blue (Balaenoptera musculus), fin (Balaenoptera physalus), sei (Balaenoptera borealis), humpback (Megaptera novaengliae), killer (Orcinus orca), and sperm (Physeter macrocephalus) whales are listed as threatened or endangered under the ESA. Federally listed pinnipeds include the Guadalupe fur seal (Arctocephalus townsendi) and Steller sea lion (Eumetopias jubatus), the latter of which also has designated Critical Habitat off the Oregon coast.
Little is known about the offshore movement of bats on the Pacific OCS, but observations from the Farallon Islands off San Francisco have regularly recorded the presence of the migratory hoary bat (Lasiurus cinereus) during migration periods. Modeling has shown that hoary bat arrivals and departures correlate with low wind speeds, low moon illumination, and relatively high degrees of cloud cover. In addition, low barometric pressure predicted arrivals. The status of bats offshore has received little to no attention and study is needed to determine their presence on the Pacific OCS.
Marine birds occur widely on the Pacific OCS off Oregon. Nearshore areas are inhabited by a variety of species of sea ducks, loons, grebes, cormorants, pelicans, gulls, terns, and several alcids. Deepwater areas 8-35 miles offshore and beyond are inhabited by albatrosses, shearwaters, petrels, storm-petrels, skuas, jaegers, alcids, and pelagic shorebirds, gulls and terns. Federally listed species under the ESA that have been extensively monitored and studied along the Oregon coast include the Western Snowy Plover (Charadrius nivosus nivosus) and Marbled Murrelet (Brachyramphus marmoratus). As studies reveal more information about the population status and movements of the endangered Short-tailed Albatross (Phoebastria albatrus) and Hawaiian Petrel (Pterodroma sandwichensis), we are finding that these species are rare, but regular off the Oregon coast at specific times of the year.
Previous workshops on offshore renewable energy have also described the potential effects that the construction and operation of energy devices could have on these taxonomic groups. Activities that can have effects on these species include construction and operational activities, vessel traffic, seismic surveys, foundation and cable installation, turbine operation, foundation protection, and the ongoing presence of cables. Resulting effects include collision and entanglement, barotrauma (particularly for bats), prey base and habitat alteration, trash ingestion (particularly for sea turtles), displacement, movement barriers, electromagnetic field effects, light attraction, pollution, and noise impacts.
Renewable energy conferences and workshops have identified knowledge and data gaps that need to be addressed to inform the planning and regulating of commercial-scale projects on the Pacific OCS. Gaps identified for sea turtles include understanding their seasonal use of the OCS particularly for post-hatchling stages; noise and EMF effects; and comprehensive population estimates; the latter will be difficult to assess due to the turtles’ solitary nature and wide distribution. Gaps identified for marine mammals include information on site-specific baseline data on occurrence, distribution, and behavior; site-specific acoustic effects on species with low frequency sensitivity; baseline information on migration routes and home ranges; impacts on gray whales (Eschrichtius robustus); monitoring to understand interactions between marine mammals and renewable energy devices; and acoustic-related effects. Gaps identified for marine birds include site-specific spatial and temporal distribution and abundance of birds at sea; nocturnal activity; important areas of bird activity that should be avoided; important migration patterns; potential effects on seabird prey; energetic consequences; and effects of EMF, noise, lights and structures, and collision risk. Sensitivity analysis and decision support tools have also been identified as necessary to assess the risk to marine birds.
The Bureau of Ocean Energy Management’s Environmental Studies Program has funded a variety of seabird and marine mammal studies to collect baseline information and assess the effects of conventional and renewable energy projects on the Pacific OCS. Recently completed studies focused on renewable energy include a summary of knowledge of select areas of the Pacific coast, an analysis of the effects of EMFs from undersea power cables on marine species, and protocols for baseline studies and monitoring for ocean renewable energy. A number of additional studies focused on renewable energy are underway or proposed, several of which should eliminate some of the identified knowledge and data gaps. These include aerial surveys of seabirds and marine mammals off the Pacific Northwest, assessing vulnerability of marine birds to offshore renewable energy devices, data synthesis and high-resolution predictive modeling of marine bird distributions in the Pacific, and several others. In addition, there are pilot studies in the Atlantic that are assessing and testing technologies that could be used for surveying and monitoring birds, bats, marine mammals, and sea turtles in the Pacific.
- Pereksta, D.M. 2012. Available Information and Data Gaps: Birds, Bats, Marine Mammals, Sea Turtles and Threatened & Endangered Species. In: Boehlert, G., C. Braby, A. S. Bull, M. E. Helix, S. Henkel, P. Klarin, and D. Schroeder, eds. 2013. Oregon Marine Renewable Energy Environmental Science Conference Proceedings. U.S. Department of the Interior, Bureau of Ocean Energy Management, Cooperative Agreement with Oregon State University M12AC00012. OCS Report BOEM 2013-0113. 149 pp.