Aerial surveys: effects of aircraft speed and environmental factors on marine megafauna

Aerial surveys are commonly used to monitor animal population and behaviour in both terrestrial and marine settings. Using aerial surveys and a density surface model (DSM) I investigated the impact of environmental factors on marine megafauna. The underestimation associated with marine aerial surveys are caused by two factors: availability and perception biases. Both of these can potentially be resolved by reducing aircraft speed. In this thesis I investigated whether observers sighted a greater number of marine animals when the aerial platform (in this case helicopters) travelled at 80 knots compared to 100 knots. No significant difference in detection of dolphins, fish schools or sharks was found, suggesting that observer training and experience has a greater impact than speed on the number and type of animals seen. Given the significant increment in cost of both observer time and helicopter charter incurred from using a 20% slower speed, without an increase in data quality, retention of the 100 knot survey speed is recommended. No significant relationship was found between dolphin and fish school counts and either sea surface temperature (SST) or chlorophyll-a (Chl-a). This suggests the involvement of other factors in the distribution and habitat selection of marine animal population.