[MARMAM] Paper: Sperm whale size-classes estimates in Irish waters (acoustically derived)

Cynthia BARILE cynthia.barile94 at gmail.com
Wed Jan 17 07:34:54 PST 2024

Dear colleagues,

Very glad to share with you all our recent publication: Click-click, who’s
there? Acoustically derived estimates of sperm whale size distribution off
western Ireland.

The article is open-access and you can find it following the link below, or
alternatively email at cynthia.barile94 at gmail.com for a pdf version.


Understanding the structure of populations is a critical element to the
establishment of management and conservation measures. Sperm whales
Physeter macrocephalus are characterised by a demographic spatial
segregation, associated with a conspicuous sexual dimorphism reflected in
their vocalisations. These characteristics make acoustic techniques very
relevant to the study of sperm whale population structure, especially in
remote, challenging environments. The reliability of using inter-pulse
intervals of sperm whale clicks to infer body size has long been verified
and extensively used. We provide the first size structure estimates of the
sperm whale population in an area where assumptions on population structure
mainly relied on sparse observations at sea, whaling records and stranding
data. Over 10,000 hours of acoustic data collected using both static
acoustic recorders and towed hydrophone arrays in Irish offshore waters
were processed using a machine learning-based tool aimed at automatically
extracting inter-pulse intervals from sperm whale recordings. Our analyses
suggested that, unlike previously thought, large males would not account
for the majority of the animals recorded in the area. We showed that adult
females/juvenile males (length 9-12 m) were predominant, accounting for 49%
(n = 788) of the number of individuals recorded (n = 1,595), while the
proportions of immature individuals (length<9 m) and adult males (length
>12 m) were well balanced, accounting for 25% (n = 394) and 26% (n = 413)
of the recorded whales, respectively. Our data also suggested some size
segregation may be occurring within the area, with smaller individuals to
the south. The implications of such findings are crucial to the management
of the population and provide an important baseline to monitor changes in
population structure, particularly relevant under changing habitat

Many thanks,

Dr. Cynthia Barile
(looking for postdoc for Sept 2024...)
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