I been spearfishing with open scuba for 7 years and continue to do so when I started CCR 3 years ago in the southern part of the Philippines. The original post question is the safety issue when spearfishing using rebreather. I have to say that first, you need to be certified or properly trained to be self-reliant diver, ie diving solo. This means, redundancy on all your life support gears. You need a lot of drill and practice time diving solo. But more important is the mindset of “safety first - fish is cheaper in the grocery - don’t trade it with your life”. The obvious advantage of CCR spearfishing is that you can spend longer underwater with no bubbles. This means, you can take your time and choose the best type and size of fish you want to have for lunch or dinner. The argument of scuba fishing is unfair and damages marine life depends on personal greed of the diver. But all greedy scuba spearo in the world could not match the destructiveness of one fleet of commercial fishing vessels that operates daily around the world. Just the same, spear only what you can consume - don’t waste the gift of the sea. Bottom line, I don’t recommend intermediate divers to start spearfishing - get your fish in the market instead.