A humpback whale with no tail was spotted swimming off the coast of Washington state, newly-released footage shows.

The animal likely lost its 15ft-wide tail - also known as its flukes - after becoming entangled, possibly in some kind of line or fishing gear according to experts.

That loss of the flukes, which are a whale's primary mode of propulsion in the water, is a likely death sentence for the creature, last reported as seen in late July.

Entanglement is one of the hazards faced by humpbacks, along with strikes or harassment by ships or boats and potential impacts of climate change on food.