New Jersey is unusual in a way that trips up out-of-state divers: there is no such thing as a paid New Jersey saltwater fishing license. When the federal government created a national saltwater angler registry (with a $15 fee) in 2011, New Jersey stood up its own state program so residents and visitors would be exempt from the federal charge. The result is the NJ Saltwater Recreational Registry Program (NJSRRP): a free, online-only, annual registration that anyone 16 or older must complete before spearfishing (or rod-and-line or hand fishing) in marine waters 4. It is legally mandatory and enforced, but it costs nothing — so a diver who assumes they must buy a saltwater 'license' is half right (registration is required) and half wrong (there is no fee). This is a genuine law-vs-expectation gap worth flagging, but it is NOT a paper-only rule: the registry is real, issued, and checked in the field.
The marine spearfishing right itself is clean and generous. N.J.A.C. 7:25-18.4 makes it lawful to take 'all species of fish' by spear, harpoon, or other missile, or by hand, while completely submerged, during each species' open season, excepting only 'specifically protected' species 2. The NJDEP Marine Digest adds the practical carve-out that lobster may not be speared 3. Everything else a diver must know flows from the ordinary size/season/possession rules — including the important catch that, unlike hook-and-line anglers who can release an undersize fish, a spearfisher is responsible for confirming the fish is legal size BEFORE striking it 3.
Freshwater is the mirror image. Spearing fish in New Jersey's fresh waters is flatly unlawful except as specified for the Delaware River 6. Game fish are rod-and-reel only. The legal way to take rough, nongame, and invasive fish is bowfishing — a bow and arrow with a line attached — for carp, suckers, American eels, catfish, gizzard shad, snakeheads, and (in the Delaware River only) American shad, under a valid freshwater fishing license (s5, s6). Crossbows are allowed for bowfishing with minimum-spec requirements, except on Greenwood Lake, and some municipalities ban discharging a bow entirely 6. So a freshwater 'spearo' in New Jersey is really a bowfisher, and only for the rough-fish list.