[MARMAM] New publication on humpback whales in the Sainte Marie Channel, Madagascar

Laurène Trudelle laurene.trudelle at gmail.com
Thu Apr 5 06:42:14 PDT 2018

Dear all,

On behalf of all co-authors, I am pleased to announce the publication of
the following paper:

L Trudelle, JB Charrassin, A Saloma, S Pous, A Kretzschmar & O Adam
(2018). First
insights on spatial and temporal distribution patterns of humpback whales
in the breeding ground at Sainte Marie Channel, Madagascar, African Journal
of Marine Science, 40:1, 75-86, DOI: 10.2989/1814232X.2018.1445028

The Sainte Marie Channel on the northeast coast of Madagascar is an
important breeding ground for humpback whales; the first observation of
birth was documented there, yet it has never been investigated for
phenology and habitat use of humpback whales. The present study was aimed
at examining temporal and spatial distribution patterns and the encounter
rate of different social groups of humpback whales during the breeding
season. We used a large set of opportunistic sightings data collected from
whale-watching boats. A total of 3 247 sightings were collected during 897
whale-watching trips conducted between June and September from 2009 to
2013. Our study complements previous information on the seasonal presence
of humpback whale social groups by demonstrating a persistent and
well-structured temporal pattern in the succession of the different groups.
Over the different years of the study period, groups without calves
consistently dominated the first 30 days of the breeding season, followed
by an increase in groups with calves. Interannual differences were observed
in the encounter rates, with significantly higher global encounter rates in
2009, 2011 and 2013 (2.2, 2.3 and 2.3 sightings h–1, respectively), and
likewise for the mean encounter rates for groups with calves. In contrast,
the encounter rate of groups without calves was similar over the study
period. Although our study area exhibits a narrow configuration and poorly
contrasting physiographic features due to its restricted spatial extent, we
report a spatially segregated pattern of humpback whale social groups in
the Sainte Marie Channel. A general linear model showed that groups with
calves were influenced by water depth and distance from shore, being
observed mostly in shallow waters (to 20 m depth) and close to the
coastline (6 km). Our findings will be useful for the development of
strategic sustained management plans by providing baseline information on
humpback whale distribution at an important but poorly documented breeding

PDF is available from the doi web link or by contacting me at
laurene.trudelle at gmail.com.

Best regards,

Laurène Trudelle
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