Saturday, January 19, 2008

Can Gippsland Lakes dolphins be all gone?

A research team conducting a survey of dolphins on the Gippsland Lakes has failed to spot a single resident dolphin, but say it is too early to tell whether a recent bloom of blue-green algae has driven them away.

A team of researchers from the Dolphin Research Institute spent three days conducting a dolphin survey on Lakes King, Victoria and Wellington and connecting waterways, but didn't spot any of the population of around 50 to 60 dolphins that regularly reside in the system.

An outbreak of blue-green algae, which was reported in the Gippsland Lakes system earlier this month, has turned parts of the lakes an iridescent shade of green. But researchers say they can't be sure whether the algal bloom has affected the dolphins or caused them to leave the lakes system.

It is the first time the researchers have conducted a survey in January and they say other factors, such as heavy use of the lakes by recreational boat users at this time of year, may have contributed to their inability to find dolphins.

People haven't seen them for over a week to three weeks .

Kate Charlton, a research officer with the Dolphin Research Institute and a Monash University PhD student, said the researchers scoured the lake thoroughly in their pursuit of dolphins.

"We've not been very successful in finding our dolphins this trip which is something in itself because we know the areas that they tend to like to hang out in. We've well and truly covered those areas and we've not been able to find them."

Kate said anecdotal reports of dolphin sightings from community members in the Gippsland Lakes region also indicated that the dolphins were keeping a low profile.

"We do always get reports about where they are seeing the animals and how many. What we have reports over the last little while is that people haven't seen them for over a week to three weeks. What we are finding is consistent with what the community is telling us."

At this stage we have more questions than answers.

The research team is surveying the dolphin population to monitor an outbreak of skin lesions which began appearing on the Gippsland Lakes' dolphin population in November.

"The lesions are a secondary fungal skin infection, indicating that it's attacking animals that are compromised in another way," Kate said.

She said the Dolphin Research Institute was tracking the dolphins to monitor the progression of lesions and working with other agencies to figure out what may have caused them in the first instance.

"At this stage we have more questions than answers."

At this stage we don't have any evidence to suggest that it [the algae] is detrimental.

Kate said researchers were also concerned about how the recent bloom of blue-green algae may be affecting dolphins who were suffering from lesions.

"It is the first time we've had dolphins with lesions and algae. They do have the ability to move out of the system and they are top predators so they can feed on multiple different fish species and squid.
"It is a concern and that's why we are down here having a look, but at this stage we don't have any evidence to suggest that it [the algae] is detrimental."

Kate said if people found a dead or stranded dolphin in the Gippsland Lakes they should contact the Dolphin Research Institute, the Victorian Strandings Network or the Department of Sustainability and Environment.

"While it's unfortunate that these animals do die, the amount of information we can get out of their deaths is crucial to managing these populations," she said.

Quick "Facts about Dolphins"