Inter-Research > ESR > v29 > n3 > p211-227  
Endangered Species Research

via Mailchimp

ESR 29:211-227 (2016)  -  DOI:

Gray whale densities during a seismic survey off Sakhalin Island, Russia

Judy E. Muir1,9,*, Laurie Ainsworth2,3, Roberto Racca4, Yury Bychkov1, Glenn Gailey5,10, Valeriy Vladimirov6, Sergei Starodymov7, Koen Bröker8

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
4JASCO Applied Sciences (Canada) Ltd., Victoria, British Columbia V8Z 7X8, Canada
5Marine Mammal Research Program, Texas A&M University at Galveston, Galveston, Texas 77553, USA
6Russian Marine Mammal Council, Nakhimovskiy ave. 36, 117218 Moscow, Russia
7ExxonMobil Russia Inc., 31 Novinsky b-r 31, 123242 Moscow, Russia
8Shell Global Solutions, Lange Kleiweg 40, 2288 GK Rijswijk, The Netherlands
9Present address: Muir Ecological Services Ltd., Victoria, British Columbia V8R 4J1, Canada
10Present address: Cascadia Research Collective, 218 ½ W. 4th Ave, Olympia, Washington 98501, USA
*Corresponding author:

ABSTRACT: Some whale populations that were severely reduced by commercial whaling have shown strong recovery since becoming protected, while others remain depleted and of high conservation concern. Small populations are particularly susceptible to anthropogenic threats, including acoustic disturbance from industrial activities such as seismic surveys. Here, we investigated if sound exposure from a 16 d seismic survey displaced gray whales Eschrichtius robustus from their coastal feeding area off northeastern Sakhalin Island, Russia. We conducted multiple shore-based surveys per day, weather permitting, and created daily 1 km2 density surfaces that provided snapshots of gray whale distribution throughout the seismic activity. A Bayesian spatio-temporal analysis was used to examine possible effects of characteristics of sound exposure from seismic airguns on gray whale occupancy and abundance. Models suggested highest occupancy in areas with moderate sound exposure. Slightly decreased densities were associated with sound exposure when the pattern for the previous 3 d was high sound on Day 2 and low sound on Days 1 and 3. Our findings should be interpreted with caution, given the low number of positive densities. This was due to success of the primary mitigation measure, which was to conduct the seismic survey as early in the feeding season as possible when few gray whales would be present. It is also possible that observed differences in occupancy and density reflect changes in prey availability rather than noise. Prey distribution and abundance data were unavailable for our study, and this important covariate could not be included in models.

KEY WORDS: Gray whales · Seismic survey · Densities · Occurrence · Abundance · Models · Functional principal components analysis · Spatio-temporal analysis · Zero-inflated

Full text in pdf format
Supplementary material 
Cite this article as: Muir JE, Ainsworth L, Racca R, Bychkov Y and others (2016) Gray whale densities during a seismic survey off Sakhalin Island, Russia. Endang Species Res 29:211-227.

Export citation
Mail this link - Contents Mailing Lists - RSS
Facebook - - linkedIn