Estimating reef shark abundance using

video surveys and agent based modelling

in Ningaloo Marine Park

Supervisor : Mathew Vanderklift.

Marine and atmospheric research, CSIRO, Perth,Western Australia.

1

Traineeship : Helene Boulloche-Sabine.

Master’s degree “BEST” Biodiversity and tropical ecosystems, Reunion island.

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

1

What is the abundance of coral reef sharks

in the Ningaloo Marine Park ?

How to make accurate estimate of

an elusive species ?

What are the key parameters to

establish a proxy of sharks’

abundance and how to obtain

information about these key

parameters ?

2

Knowing the abundance = key requirement !

Using a direct or indirect estimator :

Each method has its own set of biaises.

Examples :

Capture, mark, recapture

Tagging, tracking

Aerial detection, photographic traps

Belt transects, stationary point counts

Underwater video, baited or not.

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

3

Underwater unbaited video

Sharks : elusive species

Estimating the abundance of sparsely distributed, rare and

elusive species is challenging

Especially where direct observations are difficult

Minimize the biases on the ecosystem and on animals’

behaviour

Generate estimates of the density of sharks using

modelling

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

4

Agent based model

The model attempts to simulate the foraging behaviour of

blacktip reefshark

It requires 3 main components :

3) A way to determine when each modelled individual can be

‘detected’ by the cameras in the model.

1) Statistical distributions describing the lengths of straight-line

movements and the turning angles

2) An algorithm controlling the way each individual interacts

with habitats and with obstacles to movement

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

5

Agent based model

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

6

Distribution of the turning angles constitute a key parameter in

the agent based model.

The influence of the scale is very strong

Turning Angles

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

7

Sony DCR-HC15E

New campaign will begin in

March 2015 in Mandu.

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

8

Raspberry Pi

10 Raspberry Pi cameras are added to the new campaign

Able to record for a very long time : 20 hours

Can provide information about difference in swimming

behaviour between Dawn, Noon and Dusk.

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

Expectations of the Ningaloo project :

1) Obtain additional data for Fobs

3) Get information about foraging behaviour of coral reef shark :

acoustic data and drones.

2) Sharpen the agent based model

9

Problematics Estimate

abundance Modelling & Video

Turning angles

M&M Conclusion

1

THANK YOU FOR YOUR ATTENTION

White tip reef shark, Mandu, March 2014.