ESR 29:161-178 (2015)  -  DOI: https://doi.org/10.3354/esr00701

Distance from shore as an indicator of disturbance of gray whales during a seismic survey off Sakhalin Island, Russia

Judy E. Muir1,10,*, Laurie Ainsworth2,3, Ruth Joy4, Roberto Racca5, Yury Bychkov1, Glenn Gailey6,11, Valeriy Vladimirov7, Sergei Starodymov8, Koen Bröker9

1LGL Limited environmental research associates, Sidney, British Columbia V8L 3Y8, Canada
2Department of Statistics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
3PhiStat Research & Consulting, North Vancouver, British Columbia V7J 2Z3, Canada
4Department of Statistics & Actuarial Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
5JASCO Applied Sciences (Canada) Ltd., Victoria, British Columbia V8Z 7X8, Canada
6Marine Mammal Research Program, Texas A&M University at Galveston, Galveston, TX 77553, USA
7Russian Marine Mammal Council, Nakhimovskiy ave. 36, 117218 Moscow, Russia
8ExxonMobil Russia Inc., 31 Novinsky b-r 31, 123242 Moscow, Russia
9Shell Global Solutions, Lange Kleiweg 40, 2288 GK Rijswijk, The Netherlands
10Present address: Muir Ecological Services Ltd., Victoria, British Columbia V8R 4J1, Canada
11Present address: Cascadia Research Collective, 218 1/2 W. 4th Ave, Olympia, WA 98501, USA
*Corresponding author:

ABSTRACT: A seismic survey was conducted adjacent to the nearshore feeding ground of gray whales Eschrichtius robustus off northeastern Sakhalin Island, Russia. Scan surveys were conducted at 7 shore stations before, during and after the seismic survey. We investigated whether gray whales shifted their distribution with respect to distance from the shoreline in response to acoustic pulses from the seismic source. To do this, we used linear mixed effects modelling that included effects of detection, space and time. Data were tested for effects of magnitude and presence/absence of sound from seismic activity on whale distance from shore. Sound covariates were estimated over 3 temporal scales (8 h, 3 d and since the start of seismic activity) at locations 500 and 5000 m offshore each observation station. Sighting distance from shore was less in poor visibility and at earlier times of day. No significant effects of sound were identified, although data suggest that at most stations, sighting distance from shore increased slightly over the 2 wk of the seismic survey. The analysis was limited, however, by several factors that included low numbers of sightings throughout most of the study, non-availability of data on biomass of gray whale prey and sources of error that could not be accounted for in the model. Sensitivity to potential errors in sighting distance estimation was assessed using a correction factor based on known locations of vessels and gray whales when sighted. The model was refitted using distance-corrected sightings. Results were consistent with the original model.


KEY WORDS: Gray whale · Eschrichtius robustus · Seismic survey · Spatio-temporal analysis · Sighting distance · Anthropogenic disturbance · Cumulative sound exposure · Distance correction factor


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Cite this article as: Muir JE, Ainsworth L, Joy R, Racca R and others (2015) Distance from shore as an indicator of disturbance of gray whales during a seismic survey off Sakhalin Island, Russia. Endang Species Res 29:161-178. https://doi.org/10.3354/esr00701

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