Q: I am interested in fishing the Great Barrier Reef to get a shot at a 1,000-pound black marlin, and I have a few questions. Is it possible to confirm the weight of a marlin that size and successfully release her? If so, how is that done? What time frame would be the best, and how far in advance do I need to book the trip? 
 
—Dale Mills

A: No, there is no way to know if a fish weighs more than 1,000 pounds without killing it. Despite several rulers or tape measures that claim to give a weight based on the length of the fish, there is no single way to determine even a fish’s approximate weight besides putting it on a scale. The formula using length in inches from bottom jaw and maximum girth in inches (length x girth x girth ÷ 800) gives the best approximation but can be off by up to 15 percent.

The average so-called grander released worldwide these days probably weighs in at about 850 pounds. In the old days, a 997-
or 998-pounder was not a grander. The proliferation of nongranders that are being called granders diminishes the feats of those who really did get one or more granders.

The best time to go is anytime between late September and mid-December, and staying on a game boat and fishing for at least five days will give you your cheapest shot. If you have deep pockets, however, a mothership can’t be beat. When I was chartering on the Great Barrier Reef, I always appreciated a booking and deposit at least a year in advance, and I would take special care of those who provided them.