Same as rod and line really, size limits , daily catch limits , no take zones (although they’re few and far between), nursery areas apply. Can’t sell speared fish and it’s considered unsporting and immoral to spear on scuba.
some countries have restrictions on spearfishing at night…..
Obviously there is no catch and release but it’s not easy, the number of days you can do it each year are limited by fair weather, you have to work for your dinner and you see what you’re catching, so….. there is no accidental bycatch or fish damaged by hooks you intend to release. It’s the ultimate in selective and sustainable fishing…..