“We were able to gather evidence at least one mother returned after nine years [to Geographe].

“What that shows is there is long-term site fidelity – which means calves ... come back to that area.”

Preliminary results from the project – which draws on photos taken by volunteers, whale watching charters and Chris Burton from Western Whale Research – shows at least 229 different whales have visited the two bays in the past three decades.

This was discovered by comparing callosities – rough calcified skin patches like a callus which are grey or white in appearance with small crustaceans and barnacles also forming – on the heads of the whales which can help identify individuals much like a human fingerprint.

The research was made possible with funding by the Australian government under the National Environmental Science Program but associate professor Salgado Kent said if complementary surveys were undertaken it could help capture a broader area of locations the whales were breeding.

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“We could then ensure we’re covering the seasons consistently every year or filling in gaps where the citizen science surveys hasn’t focused on,” she said.

The whales gather in other places like Israelite Bay, Bremer Bay, Doubtful Island and several locations across the border in South Australia.

Knowing more about the species and their needs in calving grounds will help inform protection strategies for the marine mammal, like the current review of its national conservation management plan.

Such management plans are taken into account when major projects which could impact on the whales are in the development phase.

Currently there are two offshore wind projects proposed south of Perth including a 200-turbine development between Mandurah and Bunbury.

The Leeuwin Offshore Wind Farm would have a 4200 square kilometre project envelope and is currently going through the federal environmental approval process.

A referral document from the developer, Copenhagen Energy, recognises further investigations were required into the timings of whale aggregations, for a few different species, in the area to assess potential impacts.

The company recognised there could be potential impacts for whale species with activities like pile driving, but it believed that could be managed.

Kent said while more research could inform different strategies, recreational water users should also be careful in areas the whales congregated.

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“We may not see them until we’re right on top of them, so make sure we’re travelling at low speeds in these regions ... so we’re not disturbing them while they are undertaking that vital life process which is feeding the young and ensuring their calves are growing,” she said.

“Sometimes you see the calf on the back of the mum as well in a protective space ... they’re just absolutely fantastic to watch.”

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