Attempts to release a great white shark trapped in an experimental tuna farm off Port Lincoln, Australia have been thwarted by an even bigger shark.
It is believed the four-metre shark entered the fish cage, which is filled with about 100 bluefin tuna, to be followed by a sea lion.
Researchers have asked for a destruction order on the shark, but Fisheries director Will Zacharin has knocked them back. Zacharin says attempts will continue to remove the shark although a considerably larger shark posed problems during earlier efforts.
"When we dropped the net to try and entice the shark out we actually attracted a shark on the outside of the cage as well which made it extremely dangerous for putting divers back in the water either side," he said.
The Primary Industries Department says efforts to save the four-meter shark were called off this weekend due to stormy conditions but are hopeful the weather will be calmer today.
It is understood the shark entered the cage, on Thursday. However, it is unclear if the shark is still alive.
Fisheries director Will Zacharin says they will not know the shark's condition until it is monitored with a remote controlled video unit. "If the shark becomes stressed in the net itself, it may be dead at the bottom," he said.
He says if the shark is still alive, the department will attempt to free it from the cage as soon as possible, while ensuring tuna do not also escape.