Dear Marmam members,
I am pleased to share with you this new publication in Aquactic Conservation:
Bouveroux Th, Melly, B, McGregor G. & Plön S. 2018. Another dolphin in peril?
Photo-identification, occurrence, and distribution of the endangered Indian
Ocean humpback dolphin (Sousa plumbea) in Algoa Bay. Aquatic Conservation:
Marine and Freshwater Ecosystem
Abstract:
In South Africa, the humpback dolphin (Sousa plumbea) has been recognized as
the most endangered marine mammal, with a low abundance, a discontinuous
distribution, and numerous threats. This research was initiated in 2008 to
estimate the number of individual humpback dolphins in Algoa Bay, as well as
studying their residency patterns and distribution.The last boat-based study on
humpback dolphins, conducted 24 years ago, formed an important reference
against which to compare current findings. This study reveals that since the
1990s the number of identified animals decreased from 70 to 50 individuals, and
the mean group size of humpback dolphins has also decreased, from seven to
three animals. Humpback dolphin behaviour was predominantly that of foraging
and travelling, although the overall frequency of foraging still seems to have
decreased since early 1990s. Although the species was seen almost all year
round, the number of sightings per survey was lowest in January, March, and
April. The number of sightings per kilometer surveyed substantially decreased
from 0.018 sightings per kilometer in 2008 to 0.004 in 2011, and the number of
animals per kilometer also decreased from 0.042 to 0.009. The re-sighting rates
were low, ranging from one to eight times, with 52% of identified dolphins seen
only once throughout the study period. Only 6% of the individuals were seen
more than three times. Reduced humpback dolphin numbers and sighting rates
could be indicative of the rise in anthropogenic activities, such as shipping
and recreational boating, as well as a rise in pollution from vessels and urban
development. Conservation strategies, such as a Biodiversity Management Plan
for the species, are urgently needed in Algoa Bay, especially in the south-west
part of the bay, between Cape Recife and the Port Elizabeth Harbour, where the
species occurs most frequently.
The paper is available online here:
http://onlinelibrary.wiley.com/doi/10.1002/aqc.2877/full
<http://onlinelibrary.wiley.com/doi/10.1002/aqc.2877/full>
Feel free to contact me directly for a PDF copy: tbouver...@gmail.com
<mailto:tbouver...@gmail.com>
Best regards,
Thibaut Bouveroux, PhD
Marine Apex Predator Research Unit
Nelson Mandela University (NMU)
PO Box 77000
Port Elizabeth, 6031
South Africa
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