Sorry, but my browser craps out on the given link, and I don't know where the referenced clam shell graveyard is located.
But here's a reality check for you...
Most of the clam farms in the pacific supply the Japanese sushi market and other human food needs. Those food clams aren't the pretty colored ones that are sent to markets for reef keepers. They are the ugly brown ones that can't be sold to reef keeper markets, because you and I wouldn't buy them. I don't recall any real numbers, but I'd guess 90+% of farm raised clams wind up as food for people, and I don't see anything sad about feeding humanity.
If you really want to "SAVE THE CLAMS", start a movement where you, and your fellow clam lovers, swear to buy all the ugly clams that come your way. When that fails, maybe you should seek out an on-line economics course that clearly presents the concepts of "supply & demand"...