I used to spearfish extensively, but that was when fish, particularly large fish, were more numerous. At some point I realized fish were more fun to look at than to shoot.
The other issue with scuba and spearfishing is one of ethics. Spearfishing while freediving is sporting and pits your skills against the fish giving the fish an even chance. Spearfishing on scuba is in my opinion is just, pardon the pun, like shooting fish in a barrel as relatively little skill is required and consequently there is little satisfaction in it for me.
Now, don't take this wrong. Spearfishing on scuba may not be what I would call sporting but it has not caused the sharp decline in fish populations. That has a lot more to due with overfishing by hook and line anglers as well as commerical fisherman. It is a much larger issue of poor management of a resource, not one of scuba equipped spearfisherman being overly successful. But given the current state of affairs, with a limited number of fish and even more limited numbers of large fish I would prefer to look at them than to shoot them.
So I guess I don't miss a spearfishing forum on Scuba board. And you can always go to
http://www.spearboard.com/forum/ if you want to talk spearfishing.