A Dugong Story

By Seanna Cronin

Moreton Bay’s dugongs appear to be healthy and happy, says Dr Janet Lanyon.

The University of Queensland researcher wrapped up a successful week of surveys in Moreton Bay last month.

Each winter Dr Lanyon teams up with Sea World, the Sydney Aquarium and Taronga Western Plains Zoo to capture, measure and tag wild dugongs aboard the large research vessel Sea World One.

This year the researchers captured 20 animals and collected wild dugong sperm – a world first.

“It was the first time we got sperm from a live, free ranging dugong anywhere in the world,” says Dr Lanyon.

“His name is Tom Jones, because Trevor (Long, Sea World’s Director of Marine Science) was playing Tom Jones. We thought ‘this is pretty appropriate’.”

Dr Lanyon’s team name all of the animals they capture and with 800 of Moreton Bay’s estimated 1000 dugongs tagged, that’s a lot of names.

“We started off with a real Australian flavour to the names,” says Dr Lanyon.

“They were named after Australian explorers and sportsmen, people of note. We also use features of the animals, so we have Lumpy Back and various other animals we know by sight but we’ve become increasingly desperate over the years for names. Now we use any name.”

The world-first collection of wild dugong sperm was especially exciting for Taronga Western Planes Zoo postgraduate researcher Tamara Keeley, who came on the trip specifically to collect the precious genetic material.

``You usually don't get a really nice index of male reproductive biology, so this is a really good tool to do that,'' she said.

``On a very basic level we're trying to increase our understanding of the basic reproductive biology of the species to make sure they are reproducing at the rates they should be in the wild and captivity.''

Dr Lanyon’s team regularly carries out smaller mark and recapture trips throughout the year. In the summer they go out every fortnight, while in the winter they go out once a month.

“In summer the dugongs are more concentrated in big herds, which may be 150 dugongs together, and they are on the banks at high tide, so it’s easy to find them,” says Dr Lanyon.

“In winter they’re more dispersed because seagrass is patchy in winter, so you get this seagrass die off. It’s lower in nutrients and the dugongs have to forage further afield, so you find them foraging in deeper water areas as well as the shallow water. It’s harder to find them in winter.”

She says that while the shallow seagrass beds where the dugongs feed are protected in the Moreton Bay Marine Park, the mixed-use zoning areas are still a problem for the vulnerable animals.

“The feeding areas at high tide are protected, but dugongs move into deeper water areas at low tide,” she says.

“These are the places where the dugongs get hit by boats, and the other thing we find is that people are still speeding over the banks, despite the regulations. This week we’ve seen so many boaties out speeding across the banks and obviously the resources aren’t there to police it properly, so that’s a real problem.”

Dr Lanyon plans to expand her health monitoring and mark and recapture program north to Gladstone and Hervey Bay on the central Queensland coast.

Her team has also started work on a study into the acoustic capabilities of dugongs.

“We want to start looking at sensory capabilities of dugongs, similar to the work they do with the Florida manatees,” she says.

“In some situations they don’t seem to be able to hear boats approaching, so we’re hoping we’ll be able to work on the captive animals in Sea World for some preliminary studies and then start working on the wild animals to look at their detection level for boat noise.”

For more information on dugongs and University of Queensland’s research go to http://www.uq.edu.au/marinevertebrate/dugongs

To see more of Seanna's Work visit www.seannacronin.com