DOI: https://doi.org/10.3354/esr00701
copiedDistance from shore as an indicator of disturbance of gray whales during a seismic survey off Sakhalin Island, Russia
- Judy E. Muir
- Laurie Ainsworth
- Ruth Joy
- Roberto Racca
- Yury Bychkov
- Glenn Gailey
- Valeriy Vladimirov
- Sergei Starodymov
- Koen Bröker
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.
KEYWORDS
Judy E. Muir (Corresponding Author)
- LGL Limited environmental research associates, Sidney, British Columbia V8L 3Y8, Canada
Laurie Ainsworth (Co-author)
- Department of Statistics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- PhiStat Research & Consulting, North Vancouver, British Columbia V7J 2Z3, Canada
Ruth Joy (Co-author)
- Department of Statistics & Actuarial Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
Roberto Racca (Co-author)
- JASCO Applied Sciences (Canada) Ltd., Victoria, British Columbia V8Z 7X8, Canada
Yury Bychkov (Co-author)
- LGL Limited environmental research associates, Sidney, British Columbia V8L 3Y8, Canada
Glenn Gailey (Co-author)
- Marine Mammal Research Program, Texas A&M University at Galveston, Galveston, TX 77553, USA
Valeriy Vladimirov (Co-author)
- Russian Marine Mammal Council, Nakhimovskiy ave. 36, 117218 Moscow, Russia
Sergei Starodymov (Co-author)
- ExxonMobil Russia Inc., 31 Novinsky b-r 31, 123242 Moscow, Russia
Koen Bröker (Co-author)
- Shell Global Solutions, Lange Kleiweg 40, 2288 GK Rijswijk, The Netherlands
