Spearfishing as a sport has actually been around for quite a while. There are even international competitions for this sport. However, they do it a little different than you might expect. You see, it’s done without tanks. As in free diving. This makes it a bit more of a challenge. You can find more info if you google it. Try a search for Blue Water Hunters or Open Ocean Hunters.
Although there are some few individuals who are not as careful as they should be, generally speaking, I’ve found spearfishermen and women are a very selective group. They are selective about the fish that they shoot and usually either hit their target or miss it totally. Personally I find this type of harvesting much more acceptable than the thousands of tons of various fish that are killed as a result of “bycatch” from commercial fishing operations.
Too be sure, there are some risks involved and some skills that you need to develop. You should definitely get some training before you go. You should be able to find out more about the available training through your local dive shop.
Have fun, good luck, and safe dives….