Redfern J.V.,National Oceanic and Atmospheric Administration |
McKenna M.F.,West Marine |
Moore T.J.,National Oceanic and Atmospheric Administration |
Calambokidis J.,Cascadia Research |
And 6 more authors.
Conservation Biology | Year: 2013
Marine spatial planning provides a comprehensive framework for managing multiple uses of the marine environment and has the potential to minimize environmental impacts and reduce conflicts among users. Spatially explicit assessments of the risks to key marine species from human activities are a requirement of marine spatial planning. We assessed the risk of ships striking humpback (Megaptera novaeangliae), blue (Balaenoptera musculus), and fin (Balaenoptera physalus) whales in alternative shipping routes derived from patterns of shipping traffic off Southern California (U.S.A.). Specifically, we developed whale-habitat models and assumed ship-strike risk for the alternative shipping routes was proportional to the number of whales predicted by the models to occur within each route. This definition of risk assumes all ships travel within a single route. We also calculated risk assuming ships travel via multiple routes. We estimated the potential for conflict between shipping and other uses (military training and fishing) due to overlap with the routes. We also estimated the overlap between shipping routes and protected areas. The route with the lowest risk for humpback whales had the highest risk for fin whales and vice versa. Risk to both species may be ameliorated by creating a new route south of the northern Channel Islands and spreading traffic between this new route and the existing route in the Santa Barbara Channel. Creating a longer route may reduce the overlap between shipping and other uses by concentrating shipping traffic. Blue whales are distributed more evenly across our study area than humpback and fin whales; thus, risk could not be ameliorated by concentrating shipping traffic in any of the routes we considered. Reducing ship-strike risk for blue whales may be necessary because our estimate of the potential number of strikes suggests that they are likely to exceed allowable levels of anthropogenic impacts established under U.S. laws. © 2013 Society for Conservation Biology.
Yack T.M.,Southwest Fisheries Science Center |
Yack T.M.,Bio Waves Inc.. |
Barlow J.,Southwest Fisheries Science Center |
Calambokidis J.,Cascadia Research |
And 3 more authors.
Journal of the Acoustical Society of America | Year: 2013
Beaked whales are diverse and species rich taxa. They spend the vast majority of their time submerged, regularly diving to depths of hundreds to thousands of meters, typically occur in small groups, and behave inconspicuously at the surface. These factors make them extremely difficult to detect using standard visual survey methods. However, recent advancements in acoustic detection capabilities have made passive acoustic monitoring (PAM) a viable alternative. Beaked whales can be discriminated from other odontocetes by the unique characteristics of their echolocation clicks. In 2009 and 2010, PAM methods using towed hydrophone arrays were tested. These methods proved highly effective for real-time detection of beaked whales in the Southern California Bight (SCB) and were subsequently implemented in 2011 to successfully detect and track beaked whales during the ongoing Southern California Behavioral Response Study. The three year field effort has resulted in (1) the successful classification and tracking of Cuvier's (Ziphius cavirostris), Baird's (Berardius bairdii), and unidentified Mesoplodon beaked whale species and (2) the identification of areas of previously unknown beaked whale habitat use. Identification of habitat use areas will contribute to a better understanding of the complex relationship between beaked whale distribution, occurrence, and preferred habitat characteristics on a relatively small spatial scale. These findings will also provide information that can be used to promote more effective management and conservation of beaked whales in the SCB, a heavily used Naval operation and training region. © 2013 Acoustical Society of America.
Levy R.,Harvey Mudd College |
Uminsky D.,University of California at Los Angeles |
Park A.,Harvey Mudd College |
Calambokidis J.,Cascadia Research
International Journal of Non-Linear Mechanics | Year: 2011
Whale flukeprints are an often observed, but poorly understood, phenomenon. Used by whale researchers to locate whales, flukeprints refer to a strikingly smooth oval-shaped water patch which forms behind a swimming or diving whale on the surface of the ocean and persists up to several minutes. In this paper we provide a description of hydrodynamic theory and related experiments explaining the creation and evolution of these "whale footprints." The theory explains that the motion of the fluke provides a mechanism for shedding of vortex rings which subsequently creates a breakwater that damps the short wavelength capillary waves. The theory also suggests that the role of natural surfactants are of secondary importance in the early formation of these prints. © 2011 Elsevier Ltd. All rights reserved.
Ross P.S.,Canadian Department of Fisheries and Oceans |
Noel M.,Canadian Department of Fisheries and Oceans |
Noel M.,University of Victoria |
Lambourn D.,801 Phillips Road SW |
And 3 more authors.
Progress in Oceanography | Year: 2013
As high trophic level, non-migratory marine mammals, harbor seals (Phoca vitulina) inhabiting the Strait of Georgia, Juan de Fuca Strait and Puget Sound (collectively referred to as the Salish Sea) in northwestern North America provide an integrated measure of coastal food web contamination. We measured congener-specific polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), polychlorinated diphenylethers (PCDEs) and polychlorinated naphthalenes (PCNs) in blubber biopsies from free-ranging harbor seal pups inhabiting four sites in the Salish Sea in 2003. While legacy PCBs dominated the composition of these contaminants in seals at all sites (PCBs > PBDEs > PCDEs > PCNs), PBDEs were noteworthy in that they averaged as much as 59% of total PCB concentrations. We further evaluated temporal trends in seals sampled at one of these sites (Puget Sound) for PCBs and PBDEs between 1984 and 2009, and for PCDEs and PCNs between 1984 and 2003. PBDE concentrations doubled every 3.1. years between 1984 and 2003, but appeared to decline thereafter. Over the course of the 20. years between 1984 and 2003, PCB concentrations had declined by 81%, PCDEs declined by 71%, and PCNs by 98%. Overall, results suggest that regulations and source controls have noticeably reduced inputs of these contaminants to the Salish Sea, consequently reducing the associated health risks to marine wildlife. We estimate the total mass of these contaminants in the 53,000 harbor seals of the Salish Sea in 2009 to be 2.6. kg PCBs and 1.0. kg PBDEs, compared to just trace amounts of the PCDEs and PCNs. © 2013 Elsevier Ltd.
Buchanan J.B.,Cascadia Research
Journal of Raptor Research | Year: 2012
Relationships between apex predators and mesopredators have been poorly documented in predatory birds. Prediction from intraguild predation (IGP) theory suggests that following the recovery of Peregrine Falcon (Falco peregrinus) populations, the potential for Merlins (F. columbarius) to experience mesopredator suppression should increase where these species share habitat and prey resources. In Washington, both falcons prey on Dunlins (Calidris alpina) in estuarine ecosystems during the nonbreeding season. To investigate whether mesopredator suppression may have occurred, I compared aspects of the hunting behavior of Merlins at an estuary in western Washington between 1999 and 2009, when Peregrine Falcons were regularly present, with hunting behavior in the 1980s, when Peregrine Falcons did not occur at the site. Merlin hunting behavior changed substantially between the two periods. Following Peregrine Falcon recovery, Merlins hunted less frequently, used hunting flights of shorter duration and that involved fewer capture attempts per successful flight, and captured prey closer to the cover of vegetation, results that are consistent with IGP theory. Prior to Peregrine Falcon recovery, Merlins appear to have assumed the role of apex falcon predator at the site; Merlins currently coexist with Peregrine Falcons, and have altered their hunting behavior which may reduce their risk of IGP. © 2012 The Raptor Research Foundation, Inc.