When I review my photos of my dives, there are actually very few fish to be seen.
This is a fairly common misconception on what causes changes to fish populations. Hand fishing (taking octopus, spearfishing, pole-spearing, etc.) causes almost no change to fish populations. Commercial net fishing, long line fishing, etc causes major changes.
If anything, no one who does not catch fish themselves should be ever eating fish, because by eating fish caught by commercial operations you are guaranteeing wasteful by-catch killing, on a ecosphere changing level. In other words, the boat crew actually lives off the sea, and protects it. You are just part of a mechanized ecosphere destruction machine if
you eat fish. If they catch and eat, they are doing that in favor of mechanized food production. If you manage to stop them, you are
doing a bad, ecologically damaging thing.
It's kind of like complaining about hunters, but eating commercially bred livestock. One is a clear good for the environment, the other is utterly destructive and causes worldwide climate change.
But what you see in the places damaged by World War II fighting is more the result of the enormous lingering presence of heavy metals in the water. The EPA goes to Micronesia regularly, and for instance in Guam and Saipan, it will be at least a hundred years before extensive reef formation and fish population recover from both the fighting during the war, and the subsequent dumping after the war to clear land for bases, and in general to recover to civlian life.
And that would be in an ideal world where no one used cars. Because the runoff from the cars themselves, and the roads we build for the cars to play on, cause long term permanent pH changes that basically guarantee huge drops is fish populations. You went to Guam on a plane, and road to the boat dock in a car, and stayed in a hotel, all of which is the basic ongoing depression of the fish population. It's not from the crew catching anything by hand, or the guys kicking a tiny section of reef, or even torturing a sea star. A hundred guides, even if they were doing their damnedest to destroy all the reef they can, won't do a thing to affect anything but maybe the tiny bit you see.
But the cars and planes you used to get there, and their poisons affect all the parts of ocean anywhere near the islands.
This thread and my long post in it say it better:
http://www.scubaboard.com/forums/hawaii/422497-guide-handling-octopus.html
Bascially it comes down to this. We on the islands catching out own meals, and not transporting them from thousands of miles away on mechanized farms, understand what being ecologically conscious actually is.
No one who does not catch or grow their own food is doing anything ecologically sensible with regards to food. It's like beach cleanups, which takes the rich people's trash on dump in on poor people's land. That's not ecological sensitivity, that's rich people forching their will on the less fortunate.
You may well be able to force the boat crew to have to stop fishing. But you if you do, you do something bad, and something ecologically destructive, not something good, unless you feel what you see is more important than the actual health of the planet. But that's the level of ecology most people practice, so you would not be alone.
You can demand a Potemkin Village, and maybe even get it. That's what mainlanders/colonizers have been getting from the islands from a long time.