Using unmanned aerial vehicles to measure body condition of humpback and minke
whales in Antarctica
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Fredrik Christiansen1 and Lars Bejder1
1Murdoch
Background
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University, Australia
Date: 21 January 2016
Baleen whales around the world face a number of anthropogenic threats (e.g. ship strikes, net
entanglements, anthropogenic noise, human induced climate change etc.), which might impede
the rate of recovery from last centuries whaling.
Knowledge of the body condition of baleen whales, and its relationship to reproduciton and
survival, is crucial to understand non-lethal anthropogenic impacts (e.g. anthropogenic noise).
Non-invasive methods to assess body condition (health) of humpback whales and minke whales
is lacking.
We propose to use Unmanned Aerial Vehicles (UAVs) to measure seasonal variations in body
condition of humpback whales and minke whales and its influence on calf growth and body
condition in Antarctica.
Methods:
A small (<50cm diameter, <3kg) waterproof
multi-rotor (a Splashdrone quadcopter)
unmanned aerial vehicles (UAVs) will be used
to take aerial photographs of humpback
whales and minke whales (Figure 1) off the
Antarctic Peninsula (including Flandres,
Andvord, Wilhelmina and Charlotte Bay),
during the Southern hemisphere summer
feeding season. We aim to photograph all
age and maturity classes of whales. Further,
one of our aims to is photograph females
with calves, so that the relative body
condition of the females can be related to
that of their calf. The UAV will be deployed
from a smaller research vessel (5-10m),
which will be positioned 50-300m from the
targeted whale during the launch. The UAV will Figure 1. (left) Example photograph of a humpback whale taken
be initially flown above the whales at heights by a UAV by F Christiansen (Investigator) in Exmouth Gulf in in
2015. (right) Diagram of a humpback whale from an overhead
between 5 and 50 meters. Once above a whale,
perspective showing the features measured using
the UAV will take vertical photographs of the photogrammetry. The same approach will be used to measure
animal. This will allow photogrammetry to be minke whales.
used to measure the size (length and width) of
the whales from the photographs (Miller et al. 2012) (Figure 1). A live video link, providing the UAV
operator with live feed from the GoPro camera, will be used to correct the position of the UAV above the
whale and also confirm that photos of adequate quality had been obtained. The UAV will then be flown
up to an altitude of 80 to 120m, while the research vessel will move in closer to the whale (25-50m
distance from the animal) until both the whale and the boat is visible in the same photo. The size of the
research vessel will then use to scale the photograph. Once the scale photo has been obtained, the UAV
will return to the research boat and land safely in the water.
In August and September 2015, we carried out a successful pilot study in Exmouth Gulf, WA, using the
same approach to measure the body condition of humpback whales. 200 individual whales (including 49
pairs of mother and calves) were successfully measured under a Western Australian Department of Parks
and Wildlife permit and Murdoch University Ethics permit. The whales measured did not show any visible
response to the UAV, indicating that this method caused minimal disturbance to the animals. Preliminary
results from this study were presented at a UAV workshop at the Biennial Conference on the Biology of
Marine Mammals in San Francisco in December 2015.
Having measured the body condition of humpback whales in their breeding/resting grounds (i.e. Exmouth
Bay), the proposed research project will complement this data set by adding information about humpback
whales body condition from the feeding grounds, to cover the migratory cycle of these animals.
Analytical Framework
The length and width of the measured whales, obtained from the UAV photos (Figure 1), will be converted
to a measure of relative body condition. More specifically, we will use the surface area of the whale as a
proxy for body condition and estimate the relative body condition of females and calves while accounting
for their length. By comparing the body condition of individual whales to the average body condition of
the sampled population we will be able to obtain a measure of relative body condition for each sampled
whale (Christiansen et al. 2014). This will allow us to compare the relative body condition of lactating
females with the body condition of their calves (obtained using the same approach as described above),
to see how female body condition can influence calf growth and survival.
Our quantitative approach to measure body condition will also allow us to investigate variations in body
condition over time (years), and allow comparison with other study areas, to get a better understanding
of the health of humpback whales in the Southern Hemisphere.
References
Christiansen, F., G. A. Víkingsson, M. H. Rasmussen, and D. Lusseau. 2014. Female body condition affects
foetal growth in a capital breeding mysticete. Functional Ecology 28:579–588.
Miller, C. A., P. B. Best, W. L. Perryman, M. F. Baumgartner, and M. J. Moore. 2012. Body shape changes
associated with reproductive status, nutritive condition and growth in right whales Eubalaena
glacialis and E. australis. Marine Ecology Progress Series 459:135–156.