The perfect time for effective Bluefin tuna fishing trips is in July till October, with June being an excellent month, depending on how light the winter was. Federal regulations provide that boats can keep up three "large" (27 - 47") fish during any given season. This lasts from May 1 until November 30 each year, and no more than two "medium" sizes (18 – 35 inches) at one location between those days or times if they reside there exclusively throughout its duration.