A great white lie

No shark population boom

A CSIRO study has taken a bite out of rumours of a booming great white shark population on the Surf Coast.

The study has found evidence of stable great white shark numbers in Australia — a year after shark sightings caused an unprecedented number of beach closures along the Surf Coast.

The research, published in Scientific Reports yesterday, found there was an estimated “southern-western” population of 1460 adult great white sharks active between Wilson’s Promontory and northwest Western Australia.

It follows a breakthrough in the method used to estimate population numbers, now focusing on telltale marks of parental DNA collected from juveniles.

“The chances of any two juveniles in a population sharing a parent depends on how many adults are around to share the job of reproduction,” lead author Dr Richard Hillary said.

“In a small population, more juveniles share a parent than in a large population, and vice versa. And as more juveniles are sampled over time, the parental marks we detect also reveal patterns of adult survival, which we determined to be greater than 90 per cent in the east.

“We found many cases of parents (both male and female) that apparently had survived 20 or more years between the births of their children.”

A total population estimate has not yet been compiled for the southern-western population because direct estimates of juvenile survival rates are not yet available.

Humane Society International said the research should silence any calls for culling.

Between December 1, 2016, and January 10, 2017, there were 10 Surf Coast beach closures from shark sightings.

There have been very few beach closures this summer.