I wonder what certification many of the fisherman on islands and coastal areas around the world have?
On the island I live on, most of the fishermen (scuba) have either no certification or have their PADI OW. Many of these guys get bent regularly, even ones that have been trained properly because they either don't listen or don't believe that "rules" apply to them (or both). Our chamber on the island is almost always in use with a bent fishermen, and in the past 5 years we've had 3 permanent paralysis and 2 deaths.... out of a population of maybe 30 local divers.
Experience in diving counts for a lot, so too does having someone more experienced around capable of giving you a slap when you're being a nugget.