I can say that it is entirely plausible. In the flood 79 in maryborough, QLD, Australia. There were crocadiles in the street as all the croc farms flooded, to the point where the water was higher then the fences so the crocs got out, also due to the muddy river flooding that allowed wild crocs onto the streets aswell. I would imagine if any ocean waters were to rise in australia you would see bull sharks in the streets as they have already infested fresh water flood ways, and ocean floodways.