Parks and Wildlife monitor injured humpback whale off Mandurah coast

There's serious concerns for an injured humpback whale spotted off the Mandurah coast.

The ocean giant was seen just after 6am, about 500 metres off-shore.

Parks and Wildlife officers have spent the day monitoring the 6.8 metre mammal.

There were earlier fears that the whale would beach itself, but it's now moved into deeper water.

Crews will continue to keep an eye on the whale.