Fisheries Victoria has raised the alarm of increased shark activity along the coast of Victoria.
Victoria's Fairhaven beach has been closed to the public after a spike in sharks along the coast, spotted for the second day in a row.
Life savers called swimmers out of the water about 11.00am on Monday.
Life Saving Victoria personnel reported that they sighted around 30 sharks from the service's helicopter near the Victorian holiday towns of Anglesea and Fairhaven on Christmas Day.
In a statement, Fisheries Victoria said it spotted 12 sharks west of Anglesea between 1.5 and 3.5 metres in length.
Another 15 to 20 sharks of similar length were seen in waters near Fairhaven.
With temperatures in Victoria reaching the 40s, Fisheries Victoria is urging beachgoers to stick to patrolled beaches.
"Please be aware that Life Saving Victoria patrol between 10.00am and 6.00pm," Fisheries Victoria said in the statement.
"If you are considering going to the beach always go to one that is patrolled, swim between the flags and follow the instructions of life savers or authorities."
Life Saving Victoria general manager Paul Shannon told 3AW radio that there have been more shark sightings at beaches than expected for this time of year.
The Life Saving Victoria helicopter will continue to monitor shark activity near Anglesea and Fairhaven beaches.