Boat users are being urged to maintain mandatory distances from humpback whales migrating north towards Western Australia's Kimberley coast after footage revealed a small vessel hitting an animal at high speed.
It occurred last week near Broome and coincided with the annual humpback migration season as cows seek warmer waters to mate and give birth.
WA Department of Biodiversity, Conservation and Attractions' Craig Olejnik says such "distress or disturbance can have a negative impact on the whales".
"One of the key messages is to have people taking care and monitoring their speeds and surroundings to try and avoid these kinds of negative interactions," he said.
Mandatory separation distances apply on the water, with boats required to maintain a distance of 300 metres from a whale in front or behind them, and 100m from an animal to the side.
Penalties of up to $500,000 apply to anyone who intentionally breaches the rules.
Privacy in the 'bedroom'
Micheline Jenner from the Centre for Whale Research said it was particularly important that water goers observed the separation rules throughout July and August — a peak time for humpback activity.
"The Antarctic is the kitchen for the whales, and they travel on a journey that we call the humpback highway … to get to the bedroom, and the bedroom is the Kimberley," she said.
"They are seeking calm sheltered bays like the Exmouth Gulf and the Kimberley to give birth to their calves.
"In your bedroom you conduct private activity, and we also need to respect the activities of humpback whales in the bedroom in the Kimberley."
Calls for good boat 'etiquette'
Ms Jenner, who has researched whales for more than three decades, said the latest incident off the Kimberley coast was "distressing", particularly given ship strikes were among the greatest threats to whale populations.
"We need every whale in this population," she said.
"Fortunately humpback whales have been taken off the endangered species list, and their populations in both western and eastern Australia are really flourishing."
"This is really good news, but it does mean that there is more of a chance now for these whale and boat encounters because their population is somewhere between 45,000 and 48,000 individuals in WA."
Ms Jenner urged people to practice "really good boating etiquette, and keep a good look out or go slow if you see a whale".
