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

The juvenile humpback was spotted near Bundjalung National Park in what experts say is a rare, but not unprecedented event

While the case of a whale found 11km upstream in a New South Wales river this weekend was unusual, it was not unprecedented, experts say.

The juvenile humpback, which swam into the Clarence River on the state’s mid-north coast and later died, was towed out to sea on Sunday, according to NSW authorities.