Dolphins on the move

An influx in dolphins to the Gippsland Lakes over winter might give the impression that ‘they’re everywhere’ but there is only a resident population of 63 Burrunan dolphins in the Gippsland Lakes.

Dr Kate Charlton-Robb, and her team from the Marine Mammal Foundation (MMF), visit the Gippsland Lakes for a 10-day period once a season to continue their research monitoring the dolphin population that inhabits the Lakes system.

“We are constantly discovering new information about the dolphins,” explains Charlton-Robb.

“The Gippsland Lakes population is maternal based, which means most of the population is female. This only changes during the winter breeding season, when a large number of males enter the lakes. With a genetic link to the south-eastern coast of Tasmania, we believe the males might be making this annual migration to the lakes. This is unique to the Gippsland Lakes population as most other dolphin populations have their peak breeding season in summer,” Dr Charlton-Robb said.

Recent MMF research includes the effect that boats and jet skis have on the Burrunan dolphin population. The team has been collecting data on dolphin behaviour and whether the vessels are approaching the dolphins or the dolphins approach the vessels.

It has been noted that the dolphins head towards Loch Sport during summer and tend to move back into the area between Raymond Island and the Entrance in winter when there are less vessels in the Lakes.

“Research shows a dramatic shift in the way the dolphins use the Gippsland Lakes across seasons. The resident dolphins almost exclusively use Lake Victoria during summer, while in winter there is a shift to the almost exclusive use of Lake King and Reeves Channel. We believe the increase in boat traffic is what drives this shift. This could potentially affect core biological activities of the dolphins such as resting, feeding and playing. It could also cause sensitive dolphins to move from areas of high impact to areas of low impact, thus affecting behaviour and condition,” she said.

“This small and important population of dolphins must be protected from stress, including exposure to boat activity. We’re monitoring what the threats are to the dolphins and will need the community’s help to address them.”

Dr Charlton-Robb said the MMF will continue to monitor the calving rate and the crucial mother / calf association, which in other species has been noted to last for three years.

“We have been tracking our 2013 calves all the way through and it’s been observed in some cases there is still a very strong mother / calf association,” she said.

“It is interesting to note that there seems to be a longer association between mothers of female calves, whereas mothers of males will often reproduce sooner. It’s just such a unique population.”

To report dolphin sightings in the Gippsland Lakes go to fill out the TrakMM sighting info form.

Burrunan dolphin research in the Gippsland Lakes is funded by the Victorian State Government for the health of the Gippsland Lakes.