Risso's dolphins alter daily resting pattern in response to whale watching at the Azores

P>Behavioral responses of Risso's dolphins (Grampus griseus) to whale watching vessels were studied off Pico Island, Azores. Dolphin behavior was studied from a land-based lookout, enabling observations of groups in the absence and presence of vessels. The number of whale watching vessels sh...

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Bibliographic Details
Published in:Marine Mammal Science
Main Authors: Visser, Fleur, Hartman, Karin L., Rood, Ente J. J., Hendriks, Arthur J. E., Zult, Daan B., Wolff, Wim J., Huisman, Jef, Pierce, Graham J.
Format: Article in Journal/Newspaper
Language:English
Published: 2011
Subjects:
Risso's dolphin
Grampus griseus
whale watching
Azores
behavioral budget
land observations
resting behavior
BOTTLE-NOSED DOLPHINS
ORCINUS-ORCA
SAMPLING METHODS
TURSIOPS SPP
NEW-ZEALAND
TOUR BOATS
BEHAVIOR
DISTURBANCE
FLORIDA
MODEL
Lookout
New Zealand
Orca
Orcinus orca
Online Access:https://hdl.handle.net/11370/a7efd9a6-cc0a-41d3-9d66-b3c85c1ebe76
https://research.rug.nl/en/publications/a7efd9a6-cc0a-41d3-9d66-b3c85c1ebe76
https://doi.org/10.1111/j.1748-7692.2010.00398.x
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Summary:P>Behavioral responses of Risso's dolphins (Grampus griseus) to whale watching vessels were studied off Pico Island, Azores. Dolphin behavior was studied from a land-based lookout, enabling observations of groups in the absence and presence of vessels. The number of whale watching vessels showed a clear seasonal pattern, dividing the whale watching period into a low season and a high season. During the low season, Risso's dolphins rested mainly in the morning and afternoon. During the high season, Risso's dolphins rested less and did so mainly at noon, when the number of active vessels was lowest. Data analysis using a generalized additive mixed model indicated that this change in resting behavior was associated with vessel abundance. When more than five vessels were present, Risso's dolphins spent significantly less time resting and socializing. During the high season, this vessel abundance was exceeded during 20% of observation days. While we cannot be sure that the observed changes in behavior have fitness consequences for Risso's dolphins, reduced resting and socializing rates can have negative impacts on the build-up of energy reserves and on reproductive success. We suggest the adoption of precautionary management measures to regulate the timing and intensity of whale watching activities.

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