With regard to indigenous Australians, protectionism was an early policy that was taken by the Australian government. It was very similar to paternalism in that it assumed that the aboriginal people could not take care of themselves. It assumed that they needed to be protected from white Australians.
In the early colonial days, the relationship between white Australians and aborigines could be very violent. As the white population grew and white settlements expanded, conflict between them and the aborigines increased. There were numerous instances of violence and even massacres such as the Myall Creek Massacre of 1838 in New South Wales.
Because of this, the government eventually decided that something had to be done to protect the aborigines. They were dying out because of the violence and because of disease and the loss of their lands. The government therefore set up systems to try to protect them and care for them. This was very closely connected to the paternalistic policies discussed in the answer to your question on paternalism.
Thus, the policy of protectionism was very similar to paternalism. It was an early policy in Australian history meant to protect aboriginal Australians from the harm that white settlement was doing to them.