Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Does the increase in shark activity during wildlife tourism lead to higher energy expenditure (#95)

Adrienne Gooden 1 2 , Tom Clarke 1 2 3 , Lauren Meyer 1 2 4 , Charlie Huveneers 1 2
  1. Flinders University, Adelaide, SA, Australia
  2. Southern Shark Ecology Group, Flinders University, Adelaide, SA, Australia
  3. Department for Environment and Water, South Australian Government, Adelaide, South Australia, Australia
  4. Georgia Aquarium, Atlanta, Georgia, USA

Wildlife tourism is expanding globally, as is the need to quantify its potential impacts on the species targeted. Studies on the effects of marine tourism on wildlife have focused on documenting behavioural changes, but whether changes affect the energy budgets and ultimately the survival prospects of these animals is largely unknown. This is particularly acute for large predatory sharks that are difficult to study but economically and ecologically important. To assess the effects of cage-diving on white shark energy expenditure, animal-borne cameras and accelerometer loggers were deployed on 18 white sharks (Carcharodon carcharias) at a cage-diving site (Neptune Islands Group Marine Park, South Australia) and recorded shark activity for 489.7 hours. A random forest machine learning algorithm was used to predict their behaviours based on 38 hours of acceleration data with behaviours confirmed from the animal-borne cameras. The presence of cage-diving vessels led to white sharks being more active and spending more time undertaking high-energy swimming (vectorial dynamic body acceleration [VeDBA] 0.04 ± 0.03 g; doubled) and bursts of acceleration (VeDBA 0.44 ± 0.38 g; seven-fold increase) while decreasing low-energy swimming (1.5-fold). However, once put in the context of daily energy budget and accounting for the duration of cage-diving activities (~6 hours per day), energy expenditure was not substantially affected by wildlife tourism, with the presence of cage-diving vessels leading to a 0.4 – 0.7 % increase in field metabolic rate. Our findings show that while food-based tourism can influence white shark behaviour and increase energy expenditure, the overall impact on field metabolic rates and daily energy budget is minimal.