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Ever wondered how much your fish weighs and you don't have a scale. Here's a formula that works for both Tuna and Billfish.
Girth X Girth X Length Divided by 800.
Example: A tuna has a 48" girth and the length is 69." The girth is measured all around the fattest part (usually at the dorsal fin). The length is from the tip of the nose straight down the lateral line to the middle of the fork of the tail.
48 X 48 X 69 = 158,976. 158,976 divided by 800 = 198.72 pounds.
On a billfish, measure from the tip of the lower jaw to the middle of the fork.
And here's another way to measure Blue Marlin that's a bit simpler and sometimes more accurate. Simply take the measurement around the ankle of the fish just ahead of the tail. 12" will be a 200 pound fish, and for each extra inch, add 100 pounds. To make that magical "grander" mark, the ankle will be about 20 inches. This method only works for larger Marlin. (300+ pounds)
If your real lazy and don't know how to multiply and divide, go to this site and plug in the girth and length.Kona's Big Game Fish Weight Calculator
This sheet is worth printing and laminating in plastic. I always have one with me. Keep it in your boat or tackle box. It works for both Tuna and Billfish. http://www.fishkona.org/fishest.PDF
If you are confused about the girth and length, go to this site for visual info on Tuna, Billfish and sharks. Estimating Weight - Saltwater Fishing Techniques - Thai Fishing Guide
Mackerel, Redfish, Snook, Corbina, Croaker, drum, bluefish, snapper, grouper, seeabass, perch, pompano, sheepshead, rockfish, trout, barracuda, bonefish, wahoo, sturgeon, tuna, halibut, flounder, sole, etc., go to this site. Salt Water Fish Weight Calculator
For fresh water fish like Salmon, trout, herring, shad, pike, muskie, gar, walleye, splake, sunfish, bluegill, crappie, bass, striper, carp, catfish , etc., go to his site.
Fresh Water Fish Weight Calculator
Girth X Girth X Length Divided by 800.
Example: A tuna has a 48" girth and the length is 69." The girth is measured all around the fattest part (usually at the dorsal fin). The length is from the tip of the nose straight down the lateral line to the middle of the fork of the tail.
48 X 48 X 69 = 158,976. 158,976 divided by 800 = 198.72 pounds.
On a billfish, measure from the tip of the lower jaw to the middle of the fork.
And here's another way to measure Blue Marlin that's a bit simpler and sometimes more accurate. Simply take the measurement around the ankle of the fish just ahead of the tail. 12" will be a 200 pound fish, and for each extra inch, add 100 pounds. To make that magical "grander" mark, the ankle will be about 20 inches. This method only works for larger Marlin. (300+ pounds)
If your real lazy and don't know how to multiply and divide, go to this site and plug in the girth and length.Kona's Big Game Fish Weight Calculator
This sheet is worth printing and laminating in plastic. I always have one with me. Keep it in your boat or tackle box. It works for both Tuna and Billfish. http://www.fishkona.org/fishest.PDF
If you are confused about the girth and length, go to this site for visual info on Tuna, Billfish and sharks. Estimating Weight - Saltwater Fishing Techniques - Thai Fishing Guide
Mackerel, Redfish, Snook, Corbina, Croaker, drum, bluefish, snapper, grouper, seeabass, perch, pompano, sheepshead, rockfish, trout, barracuda, bonefish, wahoo, sturgeon, tuna, halibut, flounder, sole, etc., go to this site. Salt Water Fish Weight Calculator
For fresh water fish like Salmon, trout, herring, shad, pike, muskie, gar, walleye, splake, sunfish, bluegill, crappie, bass, striper, carp, catfish , etc., go to his site.
Fresh Water Fish Weight Calculator