NMFS announces final initial specifications for the 2003 fishing year for Atlantic mackerel, squid, and butterfish (MSB); including an in-season adjustment provision for the 2003 mackerel joint venture processing (JVP) annual specification. This action also specifies a method for carrying over Loligo squid Quarter I underages into Quarter III. The intent of this final rule is to promote the development and conservation of the MSB resource.