Not too extreme, considering that the fine structure was probably initiated and supported by greenpeace in the first place. Those fines punish boat and ship owners who run around in protected reefs, undoing dozens of years of reef growth in an instant.
The fines are probably overkill, but I suspect that they're that high to specifically target the particularly destructive result of negligent boat/ship operation. If Greenpeace argued against the fine, they'd probably undo a bunch of their own legislative efforts.
It is rather petty to point the finger at the govt for not updating the charts, but they're guilty of the same kind of "crime" they've lobbied against for many years, namely negligent boat/ship operation resulting in environmental damage.