An endangered whale species found off Australia's southern coast is calving less often, a decades-long research project has revealed.
The southern right whale usually calf every three years but a Curtin University-led study has found the majority of whales are having an offspring every four to five years.
"Increased calving intervals has been linked to climate change and slower recovery rates," lead researcher Dr Claire Charlton said.
"It's vital we understand how climate change and human activities may impact their ongoing survival."
For more than 30 years, researchers have conducted annual surveys of southern right whales to track their population off Australia's southern coastline.
Curtin University recently teamed up with the Minderoo Foundation, the Yalata Anangu Aboriginal Corporation and other groups to further analyse and protect the whale species.
Southern right whales were once abundant in the waters off southern Australia but intensive whaling in the 1800s drastically scaled back their numbers.
Conservation efforts have boosted the endangered species' Australian population to about 3000 but Dr Charlton said more could be done to protect them.
"We know the key threats to whale populations are habitat disruption, underwater noise and strikes from marine vessels and entanglement," she said.
"We must do everything we can, including legislative protection, to ensure their expansion into new habitats and continued recovery over time."
Dr Steve Burnell, who began the research project in 1991, said ongoing funding from the Minderoo Foundation and others ensured the whales would be monitored for years to come.
"The long-term Southern Right Whale Study is unique and irreplaceable, with the national and international value of the unbroken 30-plus year dataset growing each year," he said.
"It is vital for informing conservation management of this endangered species across the Australian marine park networks and for understanding the marine ecosystems southern right whales rely on."
