CANBERRA, Feb. 12 (Xinhua) -- Once a conservation success, southern right whales, now breeding less often, have become a warning sign of climate change impacts on marine life, new research shows.
The species, a sentinel species for climate change, provides critical insight into ecosystem changes occurring in the Southern Ocean, said a statement from Australia's Flinders University on Thursday.
The study, led by scientists from Flinders University and Curtin University in Australia with international collaborators, reveals a significant decline in southern right whale reproductive output over the past decade, driven by prolonged calving intervals.
Analyzing more than 30 years of photo-identification data from the head of the Great Australian Bight, the study found that declining breeding rates coincide with reduced Antarctic sea ice, changes in oceanic conditions, signaling broader ecosystem shifts.
Aerial survey data from 1976 to 2024 indicate that the Australian population size currently ranges about 2,300 to 3,900 individuals, representing roughly one-quarter of pre-whaling levels. Calf numbers have declined since 2017.
Similar declines have been observed off South America and South Africa, as krill-dependent predators face growing pressure from marine heatwaves, declining sea ice, and human activities such as ship strikes, noise, entanglement, and coastal development, researchers said.
Some southern right whales have shifted feeding grounds northward and broadened their diet from krill to copepods in response to environmental change, according to the study published in Scientific Reports.
"This reproductive decline represents a threshold warning for the species and highlights the urgent need for coordinated conservation efforts in the Southern Ocean in the face of anthropogenic climate change," said Claire Charlton, the long-time leader of the Australian Right Whale Program. ■