Murdoch dolphin scientists make a splash in Peel-Harvey waters

DOLPHINS of Mandurah are under close watch by Murdoch University scientists, who launched the first stage of a long-term survey in January.

Krista Nicholson, the PhD student in charge of the project, said the study will fill a large gap in the university’s long-term cetacean research, which has already begun in areas of Perth and Bunbury.

Ms Nicholson made headlines in February with incredible photos of a dolphin playing with an octopus.

So far the team consists of Ms Nicholson and three volunteers. She expects a Mandurah local to join them by the middle of the year for his honours project.

At present the field work involves boat-based surveys along predetermined tracks in the Peel-Harvey estuary and coastal areas.

Scientists have been using photos to identify the dolphins by the nicks and notches on their dorsal fins, and then record their behaviour and location.

“We’ve had 112 sightings of dolphin groups altogether since we started in January, and from all those groups we’ve identified approx 180 distinct individuals,” Ms Nicholson said.

“We’re quite happy with the number of sightings we’ve had, and the number of individuals. It’s a very good start, I think."

Ms Nicholson and her volunteers will soon undertake tissue sampling to determine genetics, sex, food, and habitat choices in the population.

They are looking to see whether there are differences between groups sighted inland and groups sighted on the coast.

 “We’ve seen certain individuals in the Peel-Harvey waterways, and then different individuals in the coastal area, but then there are parts of the Mandurah channel, southern parts of Comet Bay and the Dawesville channel where we see coastal and the Peel-Harvey animals together," Ms Nicholson said.

“We haven’t done any analysis yet, but it’s starting to paint a nice picture.”

She says the information collected in this first year will contribute to long-term monitoring, so they can keep track of how the dolphin population in the area is going, and what impacts there might be.

For her own PhD project, Ms Nicholson said she is evaluating Australian legislation on marine mammal protection "that would require the Commonwealth and state governments to define stocks, or management units, and then assess the status of these stocks”.

"The focus of my particular project is on Mandurah dolphins and the dolphins using the adjacent coastal waters," she said.

Mandurah's dolphins are the Indo-Pacific bottlenose, while further out to sea the common bottlenose dolphin is more dominant.

Ms Nicholson hopes the Peel-Harvey survey will show the limit of the Indo-Pacific bottlenose’s range.

She explained WA legislation currently only applies to three nautical miles, and from then onwards it is Commonwealth waters.

“Animals might not respect those boundaries, so I’m looking at whether the Commonwealth and Australia should have a joint management plan for those animals,” she said.


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