SYDNEY—Australian marine rescuers were working on Thursday to free a humpback whale entangled in a shark net off Queensland’s Gold Coast. Footage showed Sea World staff reaching out with blades at the end of long poles to try and cut a large mass of netting with orange buoys and yellow weights off the whale’s tail as it let out cries and thrashed its tail on the surface of the sea. “There was so much net all over it, they said it was just covered,” said one unidentified resident to local television network Nine Network. The endeavor to assist the whale had begun on Wednesday when surfers in the area had tried to free the trapped animal from the netting. Marine mammal park Sea World and the Queensland Department of Fisheries then took over the operation, as members of the whale pod stayed close by, but the rescue attempt had to …