The July meeting was held online and we were fortunate to have Dr Amanda Hodgson as our guest speaker. Amanda is a research fellow at the Aquatic Megafauna Research Unit, part of Murdoch University’s Centre for Sustainable Aquatic Ecosystems within the Harry Butler Institute. Her research is developing innovative ways to monitor and conserve large marine animals, particularly dugongs, using new technology like drones.
Dugongs live off the shore of up to 46 countries and territories in the Indo-Pacific region, with the largest populations around northern Australia. They are the only extant species in the family Dugongidae and the only fully marine Sirenian. Dugongs eat around 40kg of seagrass each day, consuming the whole plant including the rhizome. Fortunately, even if 95% of a meadow is consumed, dugong grazing seems to be beneficial as the seagrass regrows rapidly. While usually solitary (other than mothers with calves), Amanda showed us some footage from locations where they are known to congregate in herds of up to 500 individuals, including rare footage of a mother with twins.
Despite their large distribution, there is a lack of good population data for dugongs across most of their range. The traditional method of surveying involves flying light aircraft along transect lines, however this is expensive and dangerous due to the need to fly slowly at low altitude. Dr Hodgson’s research is hoping to overcome these challenges by using drones (small, remote-piloted aircraft).
The drones fly along transect lines taking overlapping photographs, with one of Amanda’s datasets being made up of 37 000 images. While humans are good at analysing these, identifying about 95% of dugongs, it would take almost 400 hours to assess that many images. Amanda’s research group has been training a computer program to do the initial identifications for a researcher review, reducing the processing time to about 18 hours.
The hope is that this surveying method will be affordable enough to be used by researchers in developing countries, with teams from the Philippines and Vanuatu already being trained. The goal is to eventually set up an online hub where researchers can share tools, advice and data with another and build up more reliable estimates of local and global populations of dugongs. This could have wider benefits for ecological research, with dugong populations being an indicator of seagrass cover, which is vital for many other marine species.
While we sometimes bemoan society’s increasing reliance on technology, research like this demonstrates how we can harness that power for conservation and connecting people to the natural world. Our thanks to Amanda for sharing her time, knowledge and beautiful footage of nature with us.