Publications (7)8.56 Total impact
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Article: Distribution of bowhead whale calls near an oil production island with fluctuating underwater sound.
Advances in experimental medicine and biology 01/2012; 730:303-6. · 1.09 Impact Factor -
Article: Marine mammal noise exposure criteria: Initial scientific recommendations.
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ABSTRACT: An expert panel reviewed the expanding literature on marine mammal (cetacean and pinniped) auditory and behavioral responses to sound exposure to develop comprehensive, scientifically based noise exposure criteria [Aquatic Mammals 33(4)]. They used precautionary extrapolation procedures to predict exposure levels above which adverse effects (both physical and behavioral) could be expected. Due to the paucity of data on long-term exposures, criteria were developed for single exposure events only. Marine mammals were broken into functional hearing groups. Exposure types were lumped into three broad classes (single pulses, multiple pulses, and nonpulses). Levels estimated to induce permanent noise-induced hearing loss were determined for each of 15 sound typeanimal group combinations. For example, injury criteria for pinnipeds in water exposed to multiple pulses were 186 dB re 1 muPa(2) -s (weighted SEL) and 218 dB(pk) re 1 muPa (unweighted peak SPL). Discrete behavioral disturbance thresholds could only be determined for exposure to single pulses. For other exposures, available data on behavioral responses were ranked by severity and significance. This severity scaling and the resulting conclusions will be described. New research required to improve criteria and to assess cumulative and ecosystem-level effects will also be considered, along with current policy andor regulatory applications.The Journal of the Acoustical Society of America 05/2009; 125(4):2517. · 1.55 Impact Factor -
Article: EFFECTS OF AN OFFSHORE OIL DEVELOPMENT ON LOCAL ABUNDANCE AND DISTRIBUTION OF RINGED SEALS (PHOCA HISPIDA) OF THE ALASKAN BEAUFORT SEA1
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ABSTRACT: This study investigates how densities of ringed seals were affected by construction and oil production activities at Northstar, an artificial island built in the nearshore Alaskan Beaufort Sea. Intensive and replicated aerial surveys of seals on landfast ice were conducted during six spring seasons: for three seasons before island construction began (1997–1999); after a winter of intensive island construction (2000); and after more limited construction plus drilling (2001) and drilling plus oil production (2002). A Poisson regression model was used to examine seal densities relative to distance from Northstar after allowance for environmental covariates. Post hoc power analysis indicated that the study design and Poisson regression approach had high power to detect small-scale changes in seal densities near Northstar if such changes had occurred. However, seal densities during spring were not significantly affected by proximity to Northstar in 2000–2002. Habitat, temporal, and weather factors did have significant effects on seal densities. This study shows that effects of the Northstar oil development on local distribution of basking ringed seals are no more than slight, and are small relative to the effects of natural environmental factors. An understanding of environmental effects is essential when assessing potential impacts of industrial activity on ringed seals.Marine Mammal Science 03/2005; 21(2):217 - 242. · 1.61 Impact Factor -
Article: Drilling and operational sounds from an oil production island in the ice-covered Beaufort sea.
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ABSTRACT: Recordings of sounds underwater and in air, and of iceborne vibrations, were obtained at Northstar Island, an artificial gravel island in the Beaufort Sea near Prudhoe Bay (Alaska). The aim was to document the levels, characteristics, and range dependence of sounds and vibrations produced by drilling and oil production during the winter, when the island was surrounded by shore-fast ice. Drilling produced the highest underwater broadband (10-10,000 Hz) levels (maximum= 124 dB re: 1 microPa at 1 km), and mainly affected 700-1400 Hz frequencies. In contrast, drilling did not increase broadband levels in air or ice relative to levels during other island activities. Production did not increase broadband levels for any of the sensors. In all media, broadband levels decreased by approximately 20 dB/tenfold change in distance. Background levels underwater were reached by 9.4 km during drilling and 3-4 km without. In the air and ice, background levels were reached 5-10 km and 2-10 km from Northstar, respectively, depending on the wind but irrespective of drilling. A comparison of the recorded sounds with harbor and ringed seal audiograms showed that Northstar sounds were probably audible to seals, at least intermittently, out to approximately 1.5 km in water and approximately 5 km in air.The Journal of the Acoustical Society of America 12/2004; 116(5):3199-211. · 1.55 Impact Factor -
Article: Directional frequency and recording (DIFAR) sensors in seafloor recorders to locate calling bowhead whales during their fall migration.
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ABSTRACT: Bowhead whales, Balaena mysticetus, migrate west during fall approximately 10-75 km off the north coast of Alaska, passing the petroleum developments around Prudhoe Bay. Oil production operations on an artificial island 5 km offshore create sounds heard by some whales. As part of an effort to assess whether migrating whales deflect farther offshore at times with high industrial noise, an acoustical approach was selected for localizing calling whales. The technique incorporated DIFAR (directional frequency and recording) sonobuoy techniques. An array of 11 DASARs (directional autonomous seafloor acoustic recorders) was built and installed with unit-to-unit separation of 5 km. When two or more DASARs detected the same call, the whale location was determined from the bearing intersections. This article describes the acoustic methods used to determine the locations of the calling bowhead whales and shows the types and precision of the data acquired. Calibration transmissions at GPS-measured times and locations provided measures of the individual DASAR clock drift and directional orientation. The standard error of the bearing measurements at distances of 3-4 km was approximately 1.35 degrees after corrections for gain imbalance in the two directional sensors. During 23 days in 2002, 10,587 bowhead calls were detected and 8383 were localized.The Journal of the Acoustical Society of America 09/2004; 116(2):799-813. · 1.55 Impact Factor -
Article: Factors influencing local abundance and haulout behaviour of ringed seals (Phoca hispida) on landfast ice of the Alaskan Beaufort Sea
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ABSTRACT: This study investigates how the local abundance of ringed seals (Phoca hispida) on landfast ice of the central Alaskan Beaufort Sea is related to habitat factors and how the haulout behaviour of seals is influenced by temporal and weather factors. An understanding of these relationships is required before the potential impacts of industrial activity on ringed seals can be assessed. Intensive and replicated aerial surveys employing strip transect methodology were conducted during the springs of 1997–1999. Data were examined with χ 2 tests and Poisson regression. The overall observed densities of ringed seals over water depths >3 m was 0.43, 0.39, and 0.63 seals/km 2 in 1997–1999, respectively. Significantly more seals occurred over intermediate water depths, especially 10–20 m. In all years, seals were widely distributed on the landfast ice, but during breakup, higher numbers of seals occurred near the ice edge. Densities were significantly lower in areas with high ice deformation and extensive melt water. There was no consistent relationship between seal sightings and time of day within the 10:00–18:00 period with surveys. The peak period of haulout occurred around 1 and 2 June. Significantly more ringed seals were observed on warm, cloudy days. There was no indication that limited winter industrial activity, including ice roads and Vibroseis, occurring within the study area in 1997–1999 significantly affected ringed seal density in spring. Résumé : Nous avons tenté de déterminer comment l'abondance locale des phoques annelés (Phoca hispida) sur la banquise du centre de la mer de Beaufort en Alaska est reliée aux caractéristiques de l'habitat et comment le compor-tement d'échouerie est influencé par les facteurs temporels et climatiques. Il est essentiel de comprendre ces relations avant de tenter d'évaluer les impacts potentiels de l'activité industrielle sur les phoques annelés. Nous avons procédé à un programme intensif de survols aériens répétés suivant une méthodologie de transects en bandes aux printemps de 1997 à 1999. Les données ont été analysées au moyen de tests de P 2 et d'une régression de Poisson. Les densités glo-bales de phoques annelés observées à des profondeurs >3 m étaient de 0,43 phoque/km 2 en 1997, de 0,39 phoque/km 2 en 1998 et de 0,63 phoque/km 2 en 1999. Il y avait significativement plus de phoques au-dessus des profondeurs moyennes, particulièrement dans les eaux de 10 à 20 m de profondeur. Au cours des 3 années, les phoques avaient une répartition étendue sur la banquise, mais, au moment de la débâcle, il y avait plus de phoques en bordure de la ban-quise. Les densités étaient significativement plus faibles dans les zones où les glaces étaient très déformées et où il y avait beaucoup d'eau due à la fonte. Il n'y avait pas de relation entre l'observation des phoques et l'heure du jour au cours des périodes de 10:00–18:00 où avaient lieu les survols. La période maximale d'échouerie se produisait autour du 1 et du 2 juin. Nous avons observé significativement plus de phoques pendant les journées chaudes et nuageuses. Rien n'indique que l'activité industrielle limitée dans la région au cours des hivers 1997 à 1999, y compris les routes de glace et les explorations vibrosismiques, ait affecté significativement les phoques annelés.Canadian Journal of Zoology 01/2002; 80(11):1900-1917. · 1.21 Impact Factor -
Article: Ringed seal densities and noise near an icebound artificial island with construction and drilling
Acoustics Research Letters Online. 4(4):112-117.
Top co-authors
Top Journals
Institutions
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2012
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LGL Alaska Research Associates, Inc.
Anchorage, AK, USA
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2004
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Greeneridge Sciences, Inc.
Santa Barbara, CA, USA
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