Dear Colleagues,
On behalf of my co-authors, I am happy to announce the publication of the following paper:
Shabangu FW, Yemane D,
Stafford KM, Ensor P, Findlay KP (2017) Modelling the effects of environmental
conditions on the acoustic occurrence and behaviour of Antarctic blue whales. PLoS
ONE 12(2): e0172705. doi:10.1371/journal.pone.0172705
Abstract:
Harvested to perilously low numbers by commercial whaling during the
past century, the large scale response of Antarctic blue whales Balaenoptera
musculus intermedia to environmental variability is poorly understood. This
study uses acoustic data collected from 586 sonobuoys deployed in the austral
summers of 1997 through 2009, south of 38ÊS, coupled with visual observations
of blue whales during the IWC SOWER line-transect surveys. The characteristic
Z-call and D-call of Antarctic blue whales were detected using an automated detection
template and visual verification method. Using a random forest model, we showed
the environmental preferences pattern, spatial occurrence and acoustic
behaviour of Antarctic blue whales. Distance to the southern boundary of the
Antarctic Circumpolar Current (SBACC), latitude and distance from the nearest
Antarctic shores were the main geographic predictors of blue whale call
occurrence. Satellite-derived sea surface height, sea surface temperature, and
productivity (chlorophyll-a) were the most important environmental predictors of
blue whale call occurrence. Call rates of D-calls were strongly predicted by
the location of the SBACC, latitude and visually detected number of whales in
an area while call rates of Z-call were predicted by the SBACC, latitude and longitude.
Satellite-derived sea surface height, wind stress, wind direction, water depth,
sea surface temperatures, chlorophyll-a and wind speed were important
environmental predictors of blue whale call rates in the Southern Ocean. Blue
whale call occurrence and call rates varied significantly in response to
inter-annual and long term variability of those environmental predictors. Our results
identify the response of Antarctic blue whales to inter-annual variability in
environmental conditions and highlighted potential suitable habitats for this
population. Such emerging knowledge about the acoustic behaviour, environmental
and habitat preferences of Antarctic blue whales is important in improving the
management and conservation of this highly depleted species.
The paper can be downloaded at: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172705
Best
regards
Fannie
Fannie
Shabangu
PhD
Candidate
Mammal
Research Institute Whale Unit
University
of Pretoria
c/o 16 Ebor Road
Wynberg,7800
South Africa
Tel: +27 21 402 3553