Authorities issue shark warning over whale that swam 11km upstream in Clarence River and later died

A young humpback whale travelled about 11km up the Clarence River in New South Wales on Saturday afternoon after being seen near Bundjalung national park. The animal, which onlookers said looked ill, moved onto a shallow sandbank and was reported dead less than half an hour later.

The sighting was first flagged by members of the public. The NSW National Parks and Wildlife Service confirmed the stranding and death, while whale researcher Dr Vanessa Pirotta and the rescue group Orrca commented on the unusual movement.

Experts described the incident as uncommon but previously seen. Pirotta said whales sometimes enter rivers and inlets out of "misadventure" or "curiosity", though this individual appeared "extremely unwell" and poor health may explain its behaviour.

The timing is atypical because most humpbacks on both coasts are currently migrating south toward Antarctica to feed on krill over summer. Orrca noted around 50,000 humpbacks travel along the eastern coast yearly, so a few sick or injured animals are expected, and pointed to two humpbacks entering Melbourne's Yarra River last year.

Authorities warned the public to stay out of the water near the carcass and nearby beaches because dead whales can draw sharks and other scavengers. People should heed local closures, and Pirotta said anyone seeing a whale in an odd place or seeming distressed should contact environmental authorities.