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AIMS
The
overall aim of the project is to collect information on the distribution,
population size, habitat preferences, behaviour and ecology of Atlantic
humpback dolphins off Namibe Province. Specific objectives of the work
are
to:
1.
Determine the
minimum number of humpback dolphins within the study area
2.
Investigate the
habitat preferences of humpback dolphins in Namibe Province
3.
Collect
behavioural data (including acoustics) on humpback dolphins
4.
Carry out a
photo-identification feasibility study on humpback dolphins
5.
Assess the
likely anthropogenic impacts upon the species in Angola
METHODS
The surveys
use a combination of boat- and shore-based survey methodology.
Boat surveys
were conducted using a semi-rigid 5-m Gemini boat. During the surveys
the boat travelled a route parallel to, and within 500 m of, the coast
to maximise encounters with Atlantic humpback dolphins. Two different
routes were surveyed, each comprising a (return) trip of approximately
29 km north or 23 km south of Flamingos. A single cetacean observer and
the boat driver maintained a visual search for dolphins. The boat’s
position was logged every minute using a Garmin GPS 76CSx, and
environmental data (Beaufort sea state, swell visibility and sun glare)
were logged throughout. Sea surface temperature (SST) was measured at
the location of sightings using a Minilog 8-bit data logger.
Shore-based
surveys were carried out at Flamingo Lodge. During dedicated watches a
single observer scanned the water with the naked eye and 10 x
binoculars. For each watch the start and end time, GPS location,
environmental data and anthropogenic impacts were recorded.
When humpback
dolphins were sighted, the position, group size, group composition, and
behaviour of the animals were recorded. Photo-identification was
attempted during both boat- and shore-based surveys, using Canon digital
SLR cameras fitted with a 100–400 mm lens. A hydrophone was deployed
during some boat surveys to record dolphin acoustic behaviour.
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