There’s an interesting discussion on this in the WetPixel Conservation forum here

The British Society of Underwater Photographers (BSoUP) has a
Code of Conduct for
underwater photographers, to which I broadly subscribe.

Following on from this …

Urchins.
I don’t have any great love for these.
They are everywhere in Tenerife, where they are not (apparently) indigenous, having been brought in as inadvertent ballast. They have no natural predators in the area, and they eat a lot of things that would otherwise feed the endemic fish populations.
They are an effective means of teaching buoyancy skills.
The local dive schools routinely slice a couple open on each dive, and I have been known to join in. But I won’t photograph the wrasses piling in for a meal.

Next … Darwin, Nemo etc.
I find the underwater world fascinating in terms of the survival strategies evolved by the different species. It really is “survival of the fittest” down there, and the damselfish who leaves the nest for a few seconds is the damselfish who suddenly doesn’t have any kids.

As an aside (viewed in these terms) Marlon – in “Finding Nemo” was a real failure as a Dad at the start of the movie. As an aside to an aside .. in the real world, he would also probably have become a “she” at that point (…. the are other implications of the lifecycle of the Anemonefish family which wouldn’t make it into a family movie) .

Sorry … where was I … OK. I do my very best not to stress fish, or stomp on coral, or rip out “souvenirs” in the pursuit of my photos. But sometimes, stuff happens, and it can’t be avoided.
And I’m not a marine biologist, so I don’t know all of the implications of my actions. But I do try (and I try to be informed), and I have deliberately missed shots (or have not got close enough for the “best” shot) where this would have led to damage.