How to Measure Your Catch
For Massachusetts marine waters minimum fish sizes are measured as total length. This is the greatest straight line length (not curved over the body) in inches as measured on a fish with its mouth closed from the anterior tip of the jaw or snout to the farthest extremity of the tail. Fish should be firmly grasped with both hands for proper measuring. Care should be taken so that the head of the fish firmly contacts the zero mark on rulers and tapes simultaneously with the tail extremity.
Tunas are measured using curved fork length. This is in a line, tracing the contour of the body from the tip of the upper jaw to the fork of the tail.
Sharks are measured from the tip of the snout to the fork of the tail.
Swordfish, sailfish and marlin are measured from the tip of the lower jaw to the tail fork.
Black sea bass are measured from the tip of the snout or jaw (mouth closed) to the farthest extremity of the tail, not including the tail filament.