In recent years there have been tons of cool discoveries from the deep sea, including bizarre new species, new biochemicals for drug development, and most interesting to me, entirely new types of diverse, reef ecosystems where we had previously assumed there were only plains of mud. The tragic irony of these discoveries is that they have been accompanied by a gold-rush kind of effort to harvest the new stocks of fish and crustaceans that we have found down there. Harvesting deep sea life is a terrible idea, for two reasons.
Reason #1- The method of harvesting, which is dragging a trawl net across the bottom, totally destroys the slow-growing corals and other non-motile organisms that form the structure of the deep sea ecosystems. It can take thousands of years for them to regrow, and in the meantime the fishes and other critters that depend on them have no place to live.
Reason #2- Deep sea organisms are sometimes abundant, but unlike shallow water organisms, they are very slow-growing and slow to reproduce. The Chilean Sea-Bass (aka Patagonian Toothfish, aka Dissostichus eleginoides) and Orange Roughy (aka Slimehead, aka Hoplostethus atlanticus) that you buy in the grocery store could be 50 and 150 years old, respectively! They simply cannot be harvested sustainably.
This nice video from the Pew Ocean Trust shows this all in a much more interesting way than I can describe...