Thirty thousand humpback whales have begun their annual migration from Antarctic waters to calving grounds off Western Australia's Kimberley coast.
The Department of Parks and Wildlife has noted an early and busy start to the migration, with five whale carcasses recorded between Albany and Coral Bay early in the season.
On Saturday, a 10 metre-long humpback whale with several bite marks, possibly from a shark, was found at Buffalo Beach near Australind.
Senior marine wildlife officer Doug Coughran said humpback and southern right whale sightings off Perth's coast would increase over the next few months.
"While humpbacks typically come close to shore due to illness, it is normal behaviour for southern right whales to swim close to breakers to rest and give birth in the shallows, especially on the south coast," he said.
Mr Coughran said those keen to catch a glimpse of the magnificent creatures should stick to whale watching guidelines to ensure the safety of the whales and themselves.
"Boats are advised to remain at a distance of 100 metres from a whale, and if a whale approaches a vessel, either place the motor in neutral or move slowly away," he said.
"Swimmers who get up close on surfboards, kayaks and paddleboards are at greater risk, as a fully grown humpback whale can weigh up to 45,000kg and may react violently especially if accompanied by a calf, which can result in serious injury or death."
Humpback whales are the fifth largest whale, growing up to 18 metres in length, and are widely distributed in all the world's oceans.
Newborn calves are born more than four metres-long and weigh about two tonnes, gaining about 45kg a day while suckling.