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 : [email protected]
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