Are Some Fish Dumber Than Others?

As I sit here counting down the days until I fish a local stocked trout pond, I can’t help but wonder if the fish will be as downright-stupid as they usually are. I’ve fished for these trout for years, and always had success, even at times when I shouldn’t have. At first it made sense; stocked trout really like powerbait and worms, so it should have been no surprise that I was catching them on those baits. As I continued to develop as an angler, my choice of lures also matured; yet I still found the same – or even better – success. Last year, when I caught the trout on just about every fly in my box, I finally came to the realization that these fish were the epitome of stocked trout: numerous, ugly, and downright credulous.

This begs the question, are all fish this gullible? Obviously the answer is no, right? They don’t call muskies the fish of 10,000 casts for nothing. And if bass were this dumb, I would have already caught a seven-pounder. But are we short-changing stocked trout? Are there certain environmental and physiological aspects at play that make us believe that stocked trout are more willing to bite our lures than other fish?

What I didn’t tell you about my luck with stocked trout at this pond is that I usually only catch them during the fall. Within that fall period, the outstanding fishing lasts for about four weeks, and then it simply stops abruptly. During the spring, catching a trout is rare, some would say nearly impossible, despite the fact that they stock a greater number of fish during this time of year. So does that mean that fall-stocked trout just have smaller and less sophisticated brains than their spring brethren?

Common sense says the answer is no. The fish, stocked albeit having been put into the wild at two different times of year, have the same genetic coding, the same brain structure, and were raised in the exact same raceways on the exact same fat-filled pellets. So what makes one easier to catch than the other? The answer is likely in the environmental and physiological factors affecting them.

What makes fall stocked trout like this rainbow easier to catch than those stocked at other times of year?

During the spring, the water starts out cold – real cold. Last year, the fish were stocked when there was but 10 feet of open water not covered by a glimmering sheet of ice. When water is cold, the fish’s metabolism slows down similar to ours when the mercury plummets. The fish care less about food at this time than they do about other environmental concerns, like water temperature and dissolved oxygen. As a result, the fish disperse and find areas that suit their needs.

In autumn, the water starts out a little warmer and gradually cools off. The water isn’t so warm that it is in danger of surpassing the trout’s thermal maximum, but it is definitely warm enough to stimulate their metabolism. Now fish are more concerned about feeding than they are getting out of harm’s way. They stay in a pod nearing the dam, where a small amount of current creates a shute through which all their food flows. In addition, weeds abound in this section of the pond, creating the perfect habitat for minnows and insect larvae that trout prey upon.

When the water cools down enough during the fall, the fish’s metabolism once again slows down, and the fish seek places with warmth and high levels of dissolved oxygen. Similar to the fall, the trout leave their pod and spread out around the pond, making it very difficult for anglers to locate them.

So, the notion that spring stocked trout are smarter than fall stocked trout is likely based on the numbers of available fish, not the fish’s gullibility. As for the trout eating just about every fly and lure I throw, I have another theory. Unlike other fish, the stocked trout you catch in California will be almost identical to the ones you catch in Maine. In the wild, the habitat fish have is entirely unique to every waterbody. Even the fish in neighboring ponds may have different tendencies and even look dissimilar. In contrast, the sharing of juvenile and broodstock trout across the country has made it so that the fish created in the hatchery of one state will have an almost identical genetic makeup to the ones found in another state’s hatchery. In addition, the concrete raceways most stocked trout spend their young years in doesn’t vary from hatchery-to-hatchery, nor does the food they’re fed. What this creates is near carbon-copies, with both the nature and nurture aspects of the fish’s upbringing being the same.

What this has done is allow anglers across the country to experiment with a number of lures, baits, and flies. What works in one region will most likely work in another region, at least until the trout adapt to their new surroundings and become “naturalized”. The idea of powerbait, egg flies, and mop flies plays off the pellet feed trout were fed in hatcheries, giving them a false sense of security when they eat these offerings. Other lures and flies take advantage of the natural instincts trout have to attack, so small streamers, spinners, and the like often get them fired up.

To summarize, we almost always have the ability to fool stocked trout, but they aren’t always there for us to fool because of environmental conditions. In these instances, we believe the trout are smarter, while in actuality, they are most likely just further dispersed.

Let’s take a look at another fish often thought to be inherently dumb: sunfish. I believe panfish are some of the most underappreciated and underrated species out there. They are credited with being easily caught and stupid, and while they are certainly the former, I’m not so sure about the latter.

If you think about the situations in which you find sunfish (i.e. bluegill, pumpkinseed, and other panfish species like perch), they are often in large schools with many individuals. While only a few individuals may be willing to bite, the sheer number of individuals outweighs the shyness of certain ones.

On the contrary, largemouth bass are considered smart and a worthy target for more advanced anglers. People find them more difficult to catch, and will spend hours only to land one or two fish. In my experience, this isn’t because the fish are more selective or smart, but rather because there are fewer of them. As the tertiary consumer in many food chains, an ecosystem only has so much room for bass. Similar to the trout, this makes the fish less accessible to anglers.

I will point out that both groups of species are carnivores. They have very similar diets, usually consisting of insects, baitfish, crustaceans, and amphibians. Sure, bass may eat slightly larger meals, but we have lures to imitate them. There is a reason big bass are often caught on small lures, though; even largemouths eat little lures like their panfish counterparts.

In a pond by my house, the roles of these fish are almost reversed; there are countless largemouth bass, nearly all of them stunted. The sunfish population, though, is much smaller than usual, but the average size of the individuals is much larger. I’ve found I catch just as many bass as sunfish in the pond, and on many of the same lures. Neither species is more or less likely to bite. They’re equally stupid and yet equally intelligent at the same time.

Bass at this pond act like their sunfish cousins.

So, is your chance of catching a 7-inch pumpkinseed the same as landing a one-pound bass? Based on my previous argument, I suppose the answer would be yes, but there are numerous variables that influence the actual rate of success. If all fish ate the same forage, grew at equal rates, and lived in identical water types, then there would be no question that the two fish would be equally difficult to trick. Unfortunately, the world isn’t that simple. There’s a reason you see just about as many 10-inch sunfish caught as 7-pound bass; it isn’t because one fish is smarter than the other, but rather because there are very few fish that attain these sizes in either species.

Obviously there are flaws in my logic, but this is just my two-cents on an entirely ridiculous topic. Some more useful information about improving your time on the water coming up next week. Until then, enjoy the bountiful stockies Mass Fish & Wildlife has gifted us in many of the state’s waters.

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