For any non-mariner readers, there are two telling and compelling reflections upon the character of those that go down to the sea in ships manifest in the law of the sea. The first is in COLREGS, the code of practice that helps prevent ships colliding. Rules for which vessel stands on and which gives way are never absolute; every vessel has an absolute responsibility to avoid collisions and no 'right' to be bloody minded. There is no 'right of way' at sea in the sense of the same on our roads; if another vessel is in the wrong, there is a duty to give way to avoid colliding. Compare and contrast to the attitude on the Highway.
The second is the universal and timeless battle amongst those that do business in great waters to save lives from the sea. Assisting those in peril is not optional for mariners; there is an obligation to do so as strong and universal as the force that compels us to breathe. We are, humans all, in constant struggle with the watery realm for our lives.
Thus leaving African migrants to drown in the Mediterranean is simply not an option for the master of any vessel making passage there and capable of assisting those in danger of drowning. No merchant ship, no warship of any nation can ignore the maritime cry for help. If they are in a position to do so.
Italy alone cannot be expected to bear this burden. Nor can she maintain her fleet of warships on sea duty solely to help migrants. All of Europe must act to stop them leaving the ports of North Africa in the first place, despite Cameron's vainglorious crowing over removing the only authority in Libya that was willing to stem the tide. The traffickers must be blocked from buying end-of-life merchant vessels; European navies should cleanse the coasts of the Maghreb with inshore vessels, sinking burning and destroying all vessels over 5m. Ports of departure must be blockaded and vessels disabled and towed back to port before the 3 mile limit.
Yes, this will violate the sovereignty of the 'Arab Spring' states, but if they can't halt the flood themselves we must do so for them.