Had some advice from David Skok of Orvis Boston in a column earlier this season. First, get the fish on ice, cut the tippet off the rod and put in in a bag. Take ke the bag, the fish , the captain of the boat (if there was one) and any witnesseses to the catch to the nearest weighmaster. Don't just go to the bait shop scale! Be sure your fish is weighed by a certified weigh master and on a scale that has bee certified in the past year by the IGFA.
You can C & R the fish (like that's going to happen to a nice bonito). You need to have a portable scale, take pictures of the fish being wieghted on land and send the leader and the scale to the IGFA for certification.
Of course a record's hard to come by and many of us will never even be close, but that doesn't mean we shouldn't know what to do.