The other night, I was on the chatroom with a couple of our members. One of them was Ard, or as he is known here, Hardyreels. In the course of our conversations, Ard mentioned a really big Coho (Silver) Salmon he caught once. I asked if he had a photo. He messaged me a copy. I got looking at it and decided it was big enough it may be worth calculating a weight on. To do this is not very hard. To determine the size of an object in a photo, all you need to know is the size of something else on the same plane as the object you wish to calculate the size of. In this case I used Ard's 3 pc. 9' fly rod. I calculated the weight of the fish by taking the length of the cork grip, 7", (most grips are 7" long) the first time a figured it out. It came to 26.195 pounds. I then decided to redo it and asked Ard for the exact measurements of the rod, because I was just assuming it was a 7" cork the first time. Ard told me it was a 7" cork and 12.25" total length from the winding check to the end of the rod. The second time I calculated the weight, I started fresh and used nothing from the first try. I did it on the photo with my photo shop the second time so I could post it here. The second calculation came out at 26.1 pounds. So doing it from scratch twice I got virtually the same weight twice, being a difference of less than 1/10 of a pound or an ounce and half or so. I feel pretty confidant the weight is pretty good on this.
The reason I decided it was worth this much effort, was having looked at all of the fly rod records for Silver (Coho) Salmon, I had the idea that Ard"s fish could beat the snot out of any of them in a fair fight. I was right. The Fresh Water Fishing Hall of Fame kept fish records for Coho is a 3 way tie for the biggest between the 2, 4 and 12lb. tippet records at 16lbs. even. Ard's fish beats them all by a good 10 pounds. The biggest catch and release fly rod record they have is a 33" fish. Ard's fish beats that at 34.766". Even given they round down to the nearest full inch, Ard's is bigger. The IGFA's biggest fly rod record for Silver Salmon is a 21 lb. 8 oz. fish caught on a 12 lb. tippet. Again Ard's fish is bigger. These are not small amounts his fish is bigger either. Ard's fish had he registered it would be the largest Silver (Coho) Salmon ever caught on a fly rod (that counts). The only fish even being remotely close to Ard's would be the Hall of Fame's 33" release record. By the way, I am not giving Ard's fish a pinched tail which it should have, it would have been over 35" with the tail pinched.
The girth is the hardest to calculate. Basically you need to be able to calculate the circumference of an ellipse or conic section.
The a in the formula is easy as it can be done the same way you calculate the Length of the fish. If you notice the small dots I did on the fish and the marks on the rod you can see where I got those. It never seems to work out where a fish is exactly multiples of what you use to measure it with, so the left over bit all you need to do is measure in mm what you are using on the photo, the size in mm of the last bit, and then divide the mm of the last bit, by the mm of the object you are using. Multiply that into the real length of the object you are using, in this case 7" for the grip. That gives you the last number to add to get a total. The b in the ellipse formula can be done by drawing a fish cross-section with using the known size of a. We have all seen enough fish by now that we can do this pretty darn close. In Fact at this point you can cheat if you are so inclined and skip the massive math involved in calculation of ellipse circumferences, and just lay a line carefully on your drawing used to calculate the value of b, and then measure the string. (Only mildly cheating.) The rest should be fairly self explanatory looking at the photo I doctored up for this post. A second method of calculating girth is to do an ellipse on the photo with fish cross section shape. Calculate the size of an inch on the photo and using dividers, go around the ellipse, counting inches. This only works on paper, so don't hold me responsible for divider marks on your monitor.
Just so you give the credit for this method to the right place, I did not invent it. It comes from Military photo analysis. It was used to toss out the old 25 lb. Walleye record. Using this method it comes out to 17.33 pounds. When confronted with the data the guy just said look "Look at the date I turned it in." It was April 1st, about 30 years earlier. I don't know about you, but I don't see that as an April fools day joke after 30 years. 30 days would have been out of line in my book. The object they used of known length, was the guy's index finger between the first and second knuckles. Center to center it is an inch on virtually all adult males.
In concusion, I would just like to welcome Ard to the "Geez, I wish I had known what the record was." club. Anyone else out there a member also? (besides me?)