The problem is not that this beast will take more fish from the oceans (because the quota is not being increased) but rather it will make strong economical sense for it to take them from as small an area as it can (to save fuel and time).
So local depletions are the real problem, the size of the vessel just allows it to keep fishing (potentially in the same location) while it fills its quota.
Can you imagine the damage to recreational fishing and the economy of Port Stephens if it decided to net The Car Park?
And why wouldn't it? Its obviously going to go wherever the largest aggregations of small pelagic's (bait) are. At times the volumes of slimy mackerel holding there are huge.
The volume of small pelagic's around the Australian coastline is such that this quota is unlikely to have a major impact overall, but the threat of sever local depletion of stocks is very real and a huge problem!