[MARMAM] Two new publications on Humpback Whales in the southwest Indian Ocean

Salvatore Cerchio scerchio at gmail.com
Thu Jan 5 09:43:00 PST 2017


Dear all,

My co-authors and I are pleased to announce the publication of two new
papers using satellite telemetry to track movements of humpback whales in
the southwest Indian Ocean.


Cerchio S, Trudelle L, Zerbini AN, Charrassin JB, Geyer Y, Mayer FX,
Andrianarivelo
N, Jung JL, Adam O, and Rosenbaum HC. 2016. Satellite telemetry of humpback
whales off Madagascar reveals insights on breeding behavior and long-range
movements within the southwest Indian Ocean. *Marine Ecology Progress
Series*, *562*, 193-209.  https://doi.org/10.3354/meps11951

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


PDFs are available from the doi web links or by contacting the
corresponding authors.

Best regards,

Salvatore


Abstracts below:


Cerchio et al. 2016. Satellite telemetry of humpback whales off Madagascar
reveals insights on breeding behavior and long-range movements within the
southwest Indian Ocean. *Marine Ecology Progress Series*, *562*, 193-209.
https://doi.org/10.3354/meps11951

ABSTRACT: Humpback whales breeding in the southwest Indian Ocean are
thought to exhibit population substructure between Madagascar and east
Africa. To investigate regional movements, breeding behavior and habitat
utilization, 23 whales were satellite-tagged off Madagascar during peak
breeding season off the northeast and southwest coasts. Mean tag duration
was 24.2 d (3 to 58 d), during which time no individual remained near the
immediate tagging sites and several displayed extensive long-range
movements. We applied a switching state-space model to estimate behavioral
modes of ‘transiting’ (b-mode approaching 1.0) vs. ‘localized’ (b-mode
approaching 2.0) movement. A general linear mixed-effects model indicated
females were more likely to display transiting behavior than males (mean
b-mode females = 1.27, males = 1.65; p = 0.031). Whales tagged in the
northeast displayed localized movements off the central east coast, whereas
whales tagged in the southwest did so on the southern coasts, with little
overlap. Long-distance movements included north-westerly trajectories to
eastern Africa and southerly transits to Walters Shoals and the Crozet
Islands. Despite these long-range movements in short periods, no whale
travelled to the northwest coast of Madagascar, nor to Mozambique or the
Mascarene Islands. These results suggest there may be more interchange
between Madagascar and central-east Africa than previously thought, and
whales off east and west Madagascar may not use the same habitat within
breeding seasons; important findings for defining sub-population structure
and conservation management strategy. Furthermore, male mating strategy may
involve more localized searching or displaying, whereas females travel more
extensively during the breeding season, observations that are consistent
with a large-scale lek mating system.


Trudelle et al, 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

ABSTRACT: 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.


-- 
**********************************
Salvatore Cerchio, Ph.D.

www.omuraswhale.org

New England Aquarium
scerchio@ <scerchio at gmail.com>neaq.org
Woods Hole Oceanographic Institution
scerchio at whoi.edu
+261-32-47-549-93 (Madagascar mobile)
+1-917-796-3363 (USA  mobile)
+1-508-289-3677 (WHOI)
Skype: scerchio
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