Ten years ago it was like a reef. You could find fish 5 ft/1.5m from the shore. The kelp beds were literal forests underwater. Now it's like a bomb went off. Plains of empty shells. Just death all around.
So I have studied this issue extensively. I personally know Jon Holcomb, the vacuum inventor. First, to dispel any myths. There is zero funding for this effort. It also takes a solid month of effort to clear a football field sized area. Compare that speed to the breeding cycle of the invasive urchin species boom and you have a very ineffective method of population control. Although his efforts were innovative. Jon will echo my comments. I live in the coastal community area between Fort Bragg and SF. I have been diving for nine years now, and I can attest to the fact that the ocean is literally barren here. We are talking no sea life except these urchin and rocks. Most if not all urchin divers have sold their boats, and laid off their crew. They have no retirement, little savings and live under or just at the poverty line. The effects spread from the South to the North. The starfish population "boom" in Oregon isn't returning to normal, they have yet to survive the maelstrom that creeps their way. It is serious devastation out here.