Michael Krasny on SF's NPR show "Forum" recently interviewed marine biologist Callum Roberts, professor of marine conservation at the University of York in England.
http://www.kqed.org/epArchive/R710181000
This is one of the problems on earth that most concerns me, way beyond fears of terrorism, etc. We brought about the effective end of the Buffalo, a massive, self perpetuating source of first class protein, on this continent. Now it's looking like humanity as a whole is replicating that in the oceans.
Lot of info out on this though it largely continues apace.
I think I've hit on a productive use for our navy. We need to establish nursery, non fishery zones in the world's oceans at once. The good professor recommends about 1/3 of ocean area total. It won't be easy. Such zones would soon be teeming with fish and the pressure to get in there would be intense. However, unless we do, the oceans will be near worthless, except for jelly fish, before long.
Many obscure, previously unexploited species are now being taken in such a manner as to seriously disrupt their breeding cycle, i.e., taken before they reach breeding age. Bottom trawling especially should be absolutely banned immediately, with the ban vigorously enforced.
Now is the time, if not us, who?