The short version for a spearfisher: you do not need a license to spearfish recreationally in Puerto Rico. If you're diving for the table and following the gear, species, closed-season, and protected-area rules on this page, you're legal. A license only comes into play for commercial fishing — anyone who sells their catch must be licensed by the DRNA.
Where the confusion comes from: the 2010 Reglamento de Pesca 7949 (Article 16) did create recreational fishing licenses — two of them, an 'agua interior' (inland) license and a 'mar' (marine) one — and even set fees for them 1. Read literally, the regulation says every recreational fisher must hold one. That literal reading is why many websites, and a first pass of this page, wrongly say a license is 'required.'
But Article 16 contains its own off-switch: the licenses only become available once the DRNA issues an 'aviso al público' — a formal public notice announcing that they can be obtained. That notice has never been issued. More than a decade after the 2010 regulation, the DRNA has never made a recreational license available to buy, and Natural Resources officers in the field do not ask recreational fishers for one (s_lic_practice). A requirement you cannot comply with because the government never opened the counter is not a real requirement.
The bottom line, confirmed directly with the DRNA by a Puerto Rico resident: recreational fishing — including spearfishing — needs no license here. This is one of the ways Puerto Rico differs from most U.S. mainland states, where a recreational saltwater license is standard. Only sell your catch and the rules change: that's commercial fishing, and it does require DRNA licensing. Regulations can change by administrative order, so if you ever intend to sell, confirm current commercial requirements with the DRNA first.