"We are not going to give her up to the zoo. Look at her home range - after swimming 3000km, they are going to put her in a pool for the rest of her life. That is torturous."
Machado was seeking advice from the New Zealand Department of Conservation in Fiordland about whether they would release Katrina into the wild or fly her home.
The Australian organisation would pay for her $1000 flight home on top of the $280 rescue flight she had last week.
They would also consider putting a tracking device on Katrina if released into the wild to ensure she made it past Tasmania's seal-infested waters.
He said Katrina was a sickly 1.7kg, almost half her body weight, and had the tendency to be snappy.
"She has a good attitude, but she tries to be vicious," Machado said.
"She is one of the hardest females I've had to deal with. She is about on par, if not better than, my wife," he quipped.
Katrina was on a heavy protein diet to gain 400g and would be soon ready for her first swim, a week after being rescued.