National Marine Mammal Laboratory

Seattle, WA, United States

National Marine Mammal Laboratory

Seattle, WA, United States
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Lander M.E.,National Marine Mammal Laboratory | Lander M.E.,University of Washington | Loughlin T.R.,National Marine Mammal Laboratory | Logsdon M.G.,University of Washington | And 2 more authors.
Endangered Species Research | Year: 2010

Among many other factors, the decline of the western distinct population segment of Steller sea lions Eumetopias jubatus in Alaska (USA) has been attributed to changes in the distribution or abundance of prey due to the cumulative effects of fisheries and large-scale climate change. However, the depletion of localized prey resources due to small-scale environmental variability and perturbations may be impeding recovery, resulting in the need to understand how the environment currently affects this species on smaller spatial and temporal scales. The objective of this study, therefore, was to assess how Steller sea lions respond to changes in localized environmental features. Satellite-relayed data loggers were deployed on juvenile Steller sea lions (n = 24) from July 2002 to May 2004 in the Aleutian Islands and Gulf of Alaska. Weekly indices of foraging effort (mean and maximum trip duration, diving activity) of Steller sea lions were examined with respect to corresponding patterns of sea surface temperature (SST) data obtained from the moderate resolution imaging spectroradiometer. An assortment of landscape metrics was used to characterize the heterogeneity of frontal features derived from SST gradients because it has been suggested that Steller sea lions depend on prey patches associated with these features. Multivariate analyses indicated that fractal dimension and patch density of frontal features were significant factors for predicting different aspects of foraging effort (p < 0.05; n = 6 models). Overall, results suggested that aggregated frontal features associated with small-scale temperature gradients were probably conducive to foraging effort of Steller sea lions, but additional mechanisms should be investigated further. © Inter-Research 2010.

Felix F.,Museo de Ballenas | Castro C.,Pacific Whale Foundation | Laake J.L.,National Marine Mammal Laboratory | Haase B.E.N.,Museo de Ballenas | Scheidat M.,University of Kiel
Journal of Cetacean Research and Management | Year: 2011

Southeastern Pacific humpback whales (Breeding Stock G) breed along the northwestern coast of South America and farther north up to Costa Rica. Photo-identification surveys conducted aboard whalewatching vessels during the migration/breeding season from June to September between 1991 and 2006 off the coast of Ecuador (2 °S, 81 °W) have produced a database of 1,511 individual whales. Comparisons of photographs produced 190 between-year re-sightings of 155 individual whales. Closed and open capture-recapture models were used to estimate abundance and survival. The best estimate of abundance in 2006 with the Chapman modified-Petersen was 6,504 (95% CI: 4,270-9,907; CV = 0.21). Abundance estimates from open population models were considerably lower due to heterogeneity in capture probability which produced a 'transient' effect. Our best estimate of true survival was 0.919 (95% CI: 0.850-0.958). Heterogeneity most likely occurred from inter-annual variation in sampling and unknown structure and variation in the migration timing and corridor. A more extensive collaborative effort including other wintering areas further north as well as integrating breeding-feeding data will help to reduce heterogeneity and increase precision in abundance and survival estimates.

Field J.C.,SWFSC NMFS NOAA | Elliger C.,Stanford University | Baltz K.,SWFSC NMFS NOAA | Gillespie G.E.,Canadian Department of Fisheries and Oceans | And 6 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2013

From 2002 to 2010, the jumbo squid (Dosidicus gigas) has been regularly encountered in large numbers throughout the California Current System (CCS). This species, usually found in subtropical waters, could affect coastal pelagic ecosystems and fisheries as both predator and prey. Neither the abundance of jumbo squid nor the optimal ocean conditions in which they flourish are well known. To understand better the potential impacts of this species on both commercial fisheries and on food-web structure we collected nearly 900 specimens from waters of the CCS, covering over 20° of latitude, over a range of depths and seasons. We used demographic information (size, sex, and maturity state) and analyzed stomach contents using morphological and molecular methods to best understand the foraging ecology of this species in different habitats of the CCS. Squid were found to consume a broad array of prey. Prey in offshore waters generally reflected the forage base reported in previous studies (mainly mesopelagic fishes and squids), whereas in more coastal waters (shelf, shelf break and slope habitats) squid foraged on a much broader mix that included substantial numbers of coastal pelagic fishes (Pacific herring and northern anchovy, as well as osmerids and salmonids in northern waters) and groundfish (Pacific hake, several species of rockfish and flatfish). We propose a seasonal movement pattern, based on size and maturity distributions along with qualitative patterns of presence or absence, and discuss the relevance of both the movement and distribution of jumbo squid over space and time. We find that jumbo squid are a generalist predator, which feeds primarily on small, pelagic or mesopelagic micronekton but also on larger fishes when they are available. We also conclude that interactions with and potential impacts on ecosystems likely vary over space and time, in response to both seasonal movement patterns and highly variable year-to-year abundance of the squid themselves. © 2012.

Pelland N.A.,University of Washington | Sterling J.T.,National Marine Mammal Laboratory | Lea M.-A.,University of Tasmania | Bond N.A.,Joint Institute for the Study of the Atmosphere and Ocean | And 3 more authors.
PLoS ONE | Year: 2014

Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastal topography suggest that biophysical interactions in these zones affect predators' prey, foraging behaviors, and potentially fitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observations of surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in some cases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus) were quantified across their range and compared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particular focus off the coast of Washington State (USA) - a known foraging ground for adult female NFS and where autonomous glider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The results show that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic, riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, were moderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, seal dives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below the surface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface wind speeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scale surface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which are known eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns by demonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thus reflecting its influence on associated NFS prey species.

Bowles A.E.,Hubbs SeaWorld Research Institute | Grebner D.M.,Bioacoustician | Musser W.B.,University of San Diego | Musser W.B.,National Marine Mammal Foundation | And 2 more authors.
Journal of the Acoustical Society of America | Year: 2015

Stereotyped pulsed calls were attributed to 11 killer whales (Orcinus orca) with and without synchronous bubble streams in three datasets collected from two facilities from 1993 to 2012. Calls with and without synchronous bubble streams and divergent overlapping high frequency components ("biphonic" vs "monophonic") were compared. Subjects produced bubbles significantly more often when calls had divergent high frequency components. However, acoustic features in one biphonic call shared by five subjects provided little evidence for an acoustic effect of synchronous bubble flow. Disproportionate bubbling supported other evidence that biphonic calls form a distinct category, but suggested a function in short-range communication. © 2015 Acoustical Society of America.

Musser W.B.,University of San Diego | Musser W.B.,National Marine Mammal Foundation | Bowles A.E.,Hubbs SeaWorld Research Institute | Grebner D.M.,Bioacoustician | Crance J.L.,National Marine Mammal Laboratory
Journal of the Acoustical Society of America | Year: 2014

Limited previous evidence suggests that killer whales (Orcinus orca) are capable of vocal production learning. However, vocal contextual learning has not been studied, nor the factors promoting learning. Vocalizations were collected from three killer whales with a history of exposure to bottlenose dolphins (Tursiops truncatus) and compared with data from seven killer whales held with conspecifics and nine bottlenose dolphins. The three whales' repertoires were distinguishable by a higher proportion of click trains and whistles. Time-domain features of click trains were intermediate between those of whales held with conspecifics and dolphins. These differences provided evidence for contextual learning. One killer whale spontaneously learned to produce artificial chirps taught to dolphins; acoustic features fell within the range of inter-individual differences among the dolphins. This whale also produced whistles similar to a stereotyped whistle produced by one dolphin. Thus, results provide further support for vocal production learning and show that killer whales are capable of contextual learning. That killer whales produce similar repertoires when associated with another species suggests substantial vocal plasticity and motivation for vocal conformity with social associates. © 2014 Acoustical Society of America.

Crance J.L.,National Marine Mammal Laboratory | Berchok C.L.,National Marine Mammal Laboratory | Bonnel J.,ENSTA Bretagne | Thode A.M.,University of California at San Diego
Polar Biology | Year: 2015

Fin whales (Balaenoptera physalus) in the North Pacific consistently range as far north as the Bering Sea. While occasional sightings of fin whales occur north of the Bering Strait, they are rarely documented north of 67°N. However, a recent increase in passive acoustic monitoring has shown that fin whales are more prevalent in the Chukchi Sea than previously thought. During a 2012 field survey in the Alaskan Chukchi Sea, fin whale calls were detected on a DiFAR sonobuoy deployed at 71.575°N, 157.823°W, 50 km off Barrow near the mouth of Barrow Canyon. On August 27, 2012, approximately 30 fin whale downsweep calls were detected over an hour and a half, at bearings of approximately 270–290° from the sonobuoy. Since only one sonobuoy was deployed, in situ localization of the calls was not possible. Post hoc range estimates using a combination of modal dispersion techniques, nonlinear time-domain warping, and geoacoustic inversion resulted in a source range estimate of less than 5 km. This location is approximately 280 and 365 km northeast of the previous closest acoustic detection and confirmed visual sighting of a fin whale, respectively. These results represent the farthest northeast record of fin whale calls in the Alaskan Arctic and illustrate the importance of continued passive acoustic monitoring in a rapidly changing environment. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA).

Skinner J.P.,Alaska SeaLife Center | Burkanov V.N.,National Marine Mammal Laboratory | Burkanov V.N.,Russian Academy of Sciences | Andrews R.D.,Alaska SeaLife Center | Andrews R.D.,University of Alaska Fairbanks
Marine Ecology Progress Series | Year: 2012

Food limitation may be one of the causes of declines in northern fur seal populations on the Pribilof Islands. This hypothesis could be tested by comparing foraging behavior from decreasing Pribilof fur seal populations and an increasing population, such as on the Lovushki Islands, Russia, but factors other than prey availability that differ between sites may also influence behavior. Therefore, we evaluated such factors, including lunar cycle, weather, seal body size, and size of recording instruments, by studying 41 lactating northern fur seals on Lovushki Island over 4 summer breeding seasons using instrument packages of various sizes. With greater moonlight, seals increased foraging trip duration, dive depth, dive duration, and time spent on the bottom of dives but decreased descent rate and diving bout duration. Larger females made shorter shore visits, spent a greater proportion of time at sea diving, and had longer dive bouts than smaller females. Tags with larger frontal surface areas and higher drag caused seals to dive longer and to descend and ascend faster during dives but did not affect foraging trip durations or mass change rates. Seals, therefore, appeared capable of compensating for instrument effects on the scale of indi vidual dives. Although lactating seals from Lovushki Island appeared to spend less foraging effort than seals from the Pribilofs, future studies should control for methodological factors and local environmental conditions before concluding whether food limitation could explain differences in population trajectories. © Inter-Research 2012.

Crance J.L.,Hubbs SeaWorld Research Institute | Crance J.L.,National Marine Mammal Laboratory | Bowles A.E.,Hubbs SeaWorld Research Institute | Garver A.,SeaWorld San Diego
Journal of Experimental Biology | Year: 2014

Killer whales (Orcinus orca) are thought to learn their vocal dialect. Dispersal in the species is rare, but effects of shifts in social association on the dialect can be studied under controlled conditions. Individual call repertoires and social association were measured in three adult female killer whales and three males (two juveniles and an adult) during two periods, 2001-2003 and 2005-2006. Three distinct dialect repertoires were represented among the subjects. An adventitious experiment in social change resulted from the birth of a calf and the transfer of two non-focal subjects in 2004. Across the two periods, 1691 calls were collected, categorized and attributed to individuals. Repertoire overlap for each subject dyad was compared with an index of association. During 2005-2006, the two juvenile males increased association with the unrelated adult male. By the end of the period, both had begun producing novel calls and call features characteristic of his repertoire. However, there was little or no reciprocal change and the adult females did not acquire his calls. Repertoire overlap and association were significantly correlated in the first period. In the second, median association time and repertoire similarity increased, but the relationship was only marginally significant. The results provided evidence that juvenile male killer whales are capable of learning new call types, possibly stimulated by a change in social association. The pattern of learning was consistent with a selective convergence of male repertoires. © 2014. Published by The Company of Biologists Ltd.

PubMed | University of San Diego, Bioacoustician, National Marine Mammal Laboratory and Hubbs SeaWorld Research Institute
Type: Comparative Study | Journal: The Journal of the Acoustical Society of America | Year: 2015

Stereotyped pulsed calls were attributed to 11 killer whales (Orcinus orca) with and without synchronous bubble streams in three datasets collected from two facilities from 1993 to 2012. Calls with and without synchronous bubble streams and divergent overlapping high frequency components (biphonic vs monophonic) were compared. Subjects produced bubbles significantly more often when calls had divergent high frequency components. However, acoustic features in one biphonic call shared by five subjects provided little evidence for an acoustic effect of synchronous bubble flow. Disproportionate bubbling supported other evidence that biphonic calls form a distinct category, but suggested a function in short-range communication.

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