So... there is another utility for target practice after all...
US have been sinking their WWII fleet in reef-absent seas, hoping they will become inhabited by larger sea-going species (there)after, thus creating an artificial life-filled reef.
(Most say it is pure BS, they just want to get rid of the f*ckton of rusting warships without creating a navigational hazard and freeing some parking space near ports, but what the hell).
Apparently, not just the natural protection the large structure provides to smaller species, it also feeds the phytoplankton directly, which makes perfect sense in a twisted way, since it is proven these sunken ships swarm with life barely immediately after reaching Kursk-depth. Pick a method that makes you more fuzzy and warm about it, or both.
Should they come up with a ship-grinding ordnance a la James Bond, perhaps the whole process should be faster then?
Pirates knew the value of sea-going recycling, and feeding the endangered species (sharks) for over 300 years now.