A whale has "breached" Victoria's lockdown laws, swimming into waters off the state's south-west coast early on Monday morning.
Logan's Beach in Warrnambool is south-east Australia's only established southern right whale nursery.
The whale was spotted by photographer Rodney Harris at the traditional whale-watching spot about 10:30am.
It has yet to be officially identified.
The sighting comes just 24 hours before the state government's protective whale exclusion zone comes into effect.
Whale, I'll be damned
The Department of Environment, Land, Water and Planning initiates the exclusion zone at Logan's Beach each year in an effort to protect the nursery.
The number of southern right whales that migrate along south-eastern Australia each year, stopping to nurse their young near Warrnambool, once numbered at almost 20,000.
But the species, named for being the "right" whale to hunt, was almost driven to extinction by whaling and now numbers less than 300.
Monday morning's sighting brought a spark of hope to whale watchers in the south-west, after no southern right whales visited the region last year.
An exclusion zone will be in place at Logan's Beach from Tuesday until the end of October, with $3,170 fines in place for any boaters that come within 200 metres of a whale.
The Conservation Regulator enforces the exclusion zone, which prevents all powered watercraft from entering the area.
"Logan's Beach is the only established nursery in south-east Australia where female southern right whales return to raise their calves, so it's vital we give them space to rest and nurse their young," said Glenn Sharp, Conservation Regulator manager of regulatory operations.
"Conservation Regulator authorised officers will patrol the exclusion zone and the south-west coast over coming months to ensure vessel operators comply with these regulations."
