[MARMAM] New publication: Summer distribution of the Mediterranean sperm whale: insights from the acoustic Accobams survey initiative.

Auriane Virgili auriane at sharetheocean.earth
Mon Oct 23 03:12:41 PDT 2023


Dear colleagues,

On behalf of my co-authors, we are pleased to share with you our recent 
publication published in Frontiers in Marine science:

"Summer distribution of the Mediterranean sperm whale: insights from the 
acoustic Accobams survey initiative."

Lerebourg, C., Boisseau, O., Ridoux, V., & Virgili, A. Frontiers in 
Marine Science, 10, 1229682.

https://doi.org/10.3389/fmars.2023.1229682

Abstract:

The Mediterranean sperm whale population, Physeter macrocephalus, is 
listed as endangered due to population decline caused by human 
activities. To mitigate the impact of these activities, accurate 
knowledge of their distribution and abundance is crucial. During their 
long dives, sperm whales are not available to visual observation, but 
since they produce sounds when they dive, they are available to acoustic 
detection. Therefore, we aimed to use towed acoustic data to model their 
habitat and fill the knowledge gap on Mediterranean sperm whale 
distribution. Generalised additive models were used to link the number 
of sperm whales detected acoustically during the ACCOBAMS Survey 
Initiative in 2018 with different environmental variables integrated 
over different depth classes, encompassing the depth range used by the 
species for foraging. Sperm whale distribution was influenced by water 
temperature at the bottom, eddy kinetic energy between 200 and 600 m, as 
well as gradients of sea surface temperature and chlorophyll-a 
concentrations. The abundance of sperm whales was estimated at 2,959 
individuals [2,077 - 4,265] in the sampled areas of the Mediterranean 
Sea. We predicted that sperm whales were mainly distributed in summer 
along the continental slope of the north-western Mediterranean basin 
from the Balearic Islands to the Ligurian Sea and off the Algerian 
coast. They were present throughout the western Mediterranean Sea and in 
the northern Ionian Sea. In contrast, predicted densities were low in 
the eastern part of the Mediterranean Sea. The use of acoustic data 
compensated for the main difficulty in studying sperm whales, the 
unavailability of animals at the surface during visual observation and 
the paucity of visual data. We thus encourage more systematic use of 
passive acoustics to study sperm whale distribution. The model 
highlighted a higher concentration of sperm whales in the western 
Mediterranean basin than in the eastern basin in summer, opening up 
avenues to improve the conservation of this endangered Mediterranean 
sub-population.

Best regards,

Auriane

-- 
Dr Auriane VIRGILI
Ingénieure de recherche / Research engineer
Share the Ocean consortium,
14 place de l'Eglise, 56870 Larmor Baden, France
E-mail : auriane at sharetheocean.earth



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