[MARMAM] New paper: Risso's dolphin's perform spin dive for deep foraging

fvisser at kelpmarineresearch.com fvisser at kelpmarineresearch.com
Mon Dec 6 01:31:38 PST 2021


Dear all,

My co-authors and I are happy to announce our paper on a spin dive 
performed by Risso's dolphins that they specifically enables them to 
very quickly reach deep prey layers. Their foraging dive starts with a 
rapid spin, a the surface, and reaches 300-600 m deep. Off the Azores, 
Risso's dolphin foraging depth also directly traced the depth of the 
deep scattering layer, foraging deep during the day and shallow at 
night.

Link to the paper:
https://royalsocietypublishing.org/doi/10.1098/rsos.202320

ABSTRACT
Foraging decisions of deep-diving cetaceans can provide fundamental 
insight into food web dynamics of the deep pelagic ocean. Cetacean 
optimal foraging entails a tight balance between oxygen-conserving dive 
strategies and access to deep-dwelling prey of sufficient energetic 
reward. Risso's dolphins (Grampus griseus) displayed a thus far unknown 
dive strategy, which we termed the spin dive. Dives started with intense 
stroking and right-sided lateral rotation. This remarkable behaviour 
resulted in a rapid descent. By tracking the fine-scale foraging 
behaviour of seven tagged individuals, matched with prey layer 
recordings, we tested the hypothesis that spin dives are foraging dives 
targeting deep-dwelling prey. Hunting depth traced the diel movement of 
the deep scattering layer, a dense aggregation of prey, that resides 
deep during the day and near-surface at night. Individuals shifted their 
foraging strategy from deep spin dives to shallow non-spin dives around 
dusk. Spin dives were significantly faster, steeper and deeper than 
non-spin dives, effectively minimizing transit time to bountiful 
mesopelagic prey, and were focused on periods when the migratory prey 
might be easier to catch. Hence, whereas Risso's dolphins were mostly 
shallow, nocturnal foragers, their spin dives enabled extended and 
rewarding diurnal foraging on deep-dwelling prey.

Reference
Fleur Visser, Onno A. Keller, Machiel G. Oudejans, Douglas P. Nowacek, 
Annebelle C.M. Kok, Jef Huisman and Elisabeth H.M. Sterck Risso’s 
dolphins perform spin dives to target deep-dwelling prey
Royal Society Open Science 1 dec 2021 
https://doi.org/10.1098/rsos.202320

All the best,

Fleur


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