Surveys by aerial drones have revealed that scalloped hammerheads are being sighted more than 250km further south than their normal habitat on the Western Coast of Australia. Scientists fear that the shift in the critically endangered species range could put it at further risk from commercial fisheries.
A report published in Austral Ecology last week detailed recurring sightings of large aggregations of the species in both the summers of 2019-20 and 2020-21.
Lead author Andrea Lopez said it was the southernmost recurrent group of scalloped hammerheads reported in Australia, pointing to a potential extension of their distribution.
But a new peer-reviewed study, reported recurring sightings of the rare species in Perth metropolitan waters in both the summer. Lopez said it was consistent with other studies that showed a relationship between warming water temperatures and species moving further south.
She said: ‘Similar research has been conducted and we are seeing that globally, marine animal distributions are shifting in response to climate change. Similar results from a study on tiger sharks were published last year.’
In 2019, the International Union on the Conservation of Nature elevated the tropical and sub-tropical scalloped hammerhead’s status to critically endangered.
Scalloped hammerheads are among the most threatened shark species globally, with estimated global declines of more than 80 per cent in the last seven decades mostly from industrial fisheries and habitat degradation.
Australian authorities are reviewing the conservation plans for scalloped hammerheads and this distribution change now puts them into areas where more commercial fishing is allowed.