How Old Is My Fish?

Field and Stream was always a magazine that I enjoyed as a kid. With the way the world is now, who even still gets magazines? The internet edition of this magazine is updated daily with new interesting facts and features. Most of their daily articles get posted on social media, as well. My favorite ones that they post are generally some sort of new world record fish or animal. The articles are okay, but the comments under the article are pure gold. I love all of the people that flood to the comments section to gripe about how they “should have thrown that back” or “should have let it walk”. And what makes it even better is half of the time the quarry in question was released. With all of those hippy PETA folks raining hellfire and damnation toward anyone that breaks a record, one particular comment is almost always typed that got me wondering myself, “Wonder how old that fish was before this idiot killed it?”

With hunting, especially the way I hunt now, age is almost always the determining factor in whether, or not, I’ll kill a buck. If we’ve got a 125” buck on the property, but know that he’s only 3.5 years old, we will pass him up in hopes that he matures another year or two into his full trophy potential. I’m not much of a turkey hunter, but I know a few guys that will pass up younger turkeys, as well. Knowing that I’m not a turkey guy, I won’t try to sit here and tell you how you can age a gobbler on foot (I truly have no idea), but I know there are ways to tell the approximate age of a buck. The best way (obviously) is to have pictures of him from multiple years. If you don’t have that, there are other ways…like his body characteristics, his demeanor, and once he’s dead, his jawbone. All of that being said, is there a way to guess the age of a fish?

As I perused the internet in search of an answer to this question, I couldn’t help but wonder how old some of those catfish were that I’d pulled out of the river through the years. Were they truly trophies in the sense of catching a fish that had been around for years? Should I have thrown them back after having evaded humans for so long? Not that it really matters now…they were all delicious. My quest for information on the topic got snagged up time after time, article after article. It seemed like each one had something different to say on the age of fish. I finally came across a study done by Michigan State University that made the most sense to me. With fish that had scales, they removed ten scales from the fish from the upper side, just under the front edge of the dorsal fin. These scales are then sent to a lab and put under a microscope. From there, the way they aged the fish was almost the same way as aging a tree with growth rings. They count the number of wide growth rings on the scale called annuli.

As amazed as I was at how this was done, I don’t have a microscope, and I don’t usually give a rip about the age of a bluegill. What about a catfish? As I read more, I learned that fish without scales, or very small scales, were harder to age. To do so, you’d need to use the spine, vertebrae, or ear bones in order to determine age. They cut them into sections after soaking in chemicals to soften them. Once again, they counted the rings to determine the age. But, what if I may want to age the fish and return it to the water? My research continued.

For the sake of this article, and mainly because its my favorite catfish, let’s keep the conversation to flathead catfish only. The deeper I dug for aging material, the more frustrated that I got. For the most part, there was no way to tell the age of a flathead catfish without killing it and slicing its spine. However, there were growth charts that can give estimates of how much weight a catfish can gain each year. I decided that this might be the best way to determine a ballpark idea of the age. Some things to consider, like any other sporting animal, or fish, in America is that habitat will play a large role in the development. If they’ve got plenty of good nutrition to munch down on, they will outgrow fish that don’t have the same resources. Also, flathead catfish are some of the quickest growing fish in the country.

A few different online articles suggested that flathead catfish can pack on 2-5 pounds a year when they are between the ages of 3-8. Some can put on more weight a year than that. Given that information, let’s start and say that a two year old flathead in the Bouie River weighs 10-12 pounds. Let’s also say that it gains four pounds a year over the next five years. That would make him (ballpark) somewhere between 30-35 pounds by the time he’s 8 years old. Given the average lifespan of a flathead catfish is somewhere in the 20 year ballpark, a 30-35 pound fish hardly sounds like a mature trophy at this point. Obviously, flatheads can live longer than 20 years, and they certainly get a lot bigger than 30-35 pounds. On the other hand, it made me feel a little bit better about keeping all of those fish in that thirty pound range over the years. And for everyone that thinks they don’t taste good when they get that large, you’re right. Throw them back…I’ll catch ‘em later.

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