[MARMAM] Influence of environmental parameters on movements and habitat utilization of humpback whales (Megaptera novaeangliae) in the Madagascar breeding ground.

Laurène Trudelle laurene.trudelle at gmail.com
Mon Jan 2 06:41:08 PST 2017

Dear all,

My co-authors and I are pleased to announce the publication of the
following paper in Royal Society Open Science.

Trudelle L, Cerchio S, Zerbini AN, Geyer Y, Mayer FX, Jung JL, Hervé, MR,
Pous S, Sallée JB, Rosenbaum HC, Adam O, and Charrassin JB, 2016. Influence
of environmental parameters on movements and habitat utilization of
humpback whales (*Megaptera novaeangliae*) in the Madagascar breeding
ground. R. Soc.open sci. 3: 160616. http://dx.doi.org/10.1098/rsos.160616

Assessing the movement patterns and key habitat features of breeding
humpback whales is a prerequisite for the conservation management of this
philopatric species. To investigate the interactions between humpback whale
movements and environmental conditions off Madagascar, we deployed 25
satellite tags in the northeast and southwest coast of Madagascar. For each
recorded position, we collated estimates of environmental variables and
computed two behavioural metrics: behavioural state of ‘transiting’
(consistent/directional) versus ‘localized’ (variable/nondirectional), and
active swimming speed (i.e. speed relative to the current). On coastal
habitats (i.e. bathymetry<200m and in adjacent areas), females showed
localized behaviour in deep waters (191±20 m) and at large distances
(14±0.6 km) from shore, suggesting that their breeding habitat extends
beyond the shallowest waters available close to the coastline. Males’
active swimming speed decreased in shallow waters, but environmental
parameters did not influence their likelihood to exhibit localized
movements, which was probably dominated by social factors instead. In
oceanic habitats, both males and females showed localized behaviours in
shallow waters and favoured high chlorophyll-a concentrations. Active
swimming speed accounts for a large proportion of observed movement speed;
however, breeding humpback whales probably exploit prevailing ocean
currents to maximize displacement. This study provides evidence that
coastal areas, generally subject to strong human pressure, remain the core
habitat of humpback whales off Madagascar. Our results expand the knowledge
of humpback whale habitat use in oceanic habitat and response to
variability of environmental factors such as oceanic current and
chlorophyll level.

Kind Regards, Laurène Trudelle
Laurène Trudelle, Ph.D

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