The question about conservation is a really good one. Obviously that is a word like "sustainable" that everyone will define differently. So I can only give my personal views.
Because my father was a marine biologist who studied sharks, I was thrown in as shark bait at an early age for some of his experiments on chemoreception. So even before I began scuba diving, I had seen reefs the way many of you did back in the 1960s and 70s.
What we have all seen, but particularly in the Caribbean, has been what Jeremy Jackson calls the "shifting baseline." (If you haven't caught some of the PSAs on their site, you are missing some great laughs. See
http://www.shiftingbaselines.org)
So, another way to look at this is that we have seen conservation in reverse -- over-exploition. It is the same old story -- global population growth X consumption X a global economy. I remember when they built the first ice plant in northern Palawan and suddenly what had been a local economy of what lobster could be consumed or sold at local markets turned overnight into a global market with Taiwanese ships pulling up and buying lobster by the ton. The lobster were gone fairly quickly from Bacuit Bay.
Now, I like to eat lobster and I like to have an aquarium full of pretty reef organisms. Unfortunately, as we have seen all over the world, one fishery after another has failed and many have been closed. It was a pretty big shock to me after living overseas for many years and teaching coastal management overseas and highlighting what a leader California was -- to return to teach at UCLA and find that abalone were gone and the fishery closed -- along with many others.
Bottom line -- demand is exceeding supply and if we don't "fix" this imbalance we may push some reef ecosystems beyond their ability to recover naturally. This is what seems to be happening on reefs such as in Jamaica that were overfished as early as the 1950s. Reefs that were 85% coral in the early 1970s are now 5% coral and 95% algae ( or protists as they are now classified).
Many on this site are involved in growing and reproducing marine organisms and know more about this than most academic scientists.
What we need is to better connect this knowledge to R &D into aquaculture of marine organisms both for food and for aquaria -- so that we can balance demand with supply. In addition, if we can set aside a significant portion of our oceans (say 30%) as marine protected areas, then natural reseeding and natural growth will allow many of these areas to recover.
So this is how I view conservation -- setting aside sufficient natural areas so that we are not losing more than we are gaining -- and coming up with economic incentives for people to take better care of their marine resources and hopefully make money from them in perpetuity.
Right now, we are in a losing battle. The changes are so fast and so dramatic that ecosystems such as reefs in Jamaica are no longer the same ecosystems they were 30 years ago. For those of us old enough to have witnessed these declines it is pretty sad. We have ten teams in the Caribbean tracking the bleaching from Jamaica to Venezuela and while our data are not as bad as those reported in the press, we lost a lot of coral this year -- the hottest year in recorded history.