Here's a chart that ages Bluefin tuna. It also gives an estimated weight to length for BFT. It seems that most of the BFT caught on the East coast this year by people on this board are between 4 and 7 years old. Growth and weight is interesting. If you caught a 67" one this year, it will be 74" next year and gain over 61 pounds. Five years from now it will be 96" and go from 184 pounds to 539 pounds.