http://www.ct.gov/deep/lib/deep/fishing/...es_12232015.pdf

http://www.ct.gov/deep/lib/deep/fishing/saltwater/marinecirc.pdf

17BCommercial Fishing
A commercial fishing license is required to take or land any regulated species, i.e.: finfish, crustaceans, sea scallop, squid, horseshoe crab, whelk or bait species (see Appendix IV: Bait Species) for commercial purposes or to use any commercial fishing gear to take regulated species whether for personal use or for sale.

“Commercial fishing gear” as defined in 26-1(8) of the Connecticut General Statutes means any equipment commonly used to take regulated species, i.e. finfish, crustaceans, sea scallops, squid, horseshoe crabs, whelk or bait species for commercial purposes including, but not limited to, lobster pots, otter trawls, beam trawls, balloon trawls, mid-water trawls, sea scallop dredges, scoop nets, scap nets, seines, trap nets, fyke nets, crab traps, gill nets, trammel nets, set lines, long lines, hook and line, and if such fishing is conducted for commercial purposes, minnow seines, minnow traps, eel pots, fish pots, pound nets, throw nets or similar devices and any equipment listed as commercial fishing gear in regulations adopted by the Commissioner of Energy and Environmental Protection.

You will find most information in the circular.