Catching up on periodical reading and noticed that seleltope has been approved for use in the EU, China
It is basically a neurotransmitter than stimulates barnacle larva to swim and therefore prevent adhesion. Amazingly low 0.1% concentration needed to be effective and thus far the results are looking promising (akin to pre-tin ban).
Paints has started commercial
trails and I believe they have secured exclusivity for a bit of time, but if this works, antifouling might see a turnaround we haven't seen in two decades!