Fish Intelligence

Can a fish be smart today and driven by instinct tomorrow?

Largemouth bass

Pictured above: largemouth bass are curious creatures. They will calmly investigate a diver underwater.

I’ve been fishing as long as I can remember, and I grew up with the idea that some fish were smart, especially big ones. There was a story my father told years ago of a huge brown trout named Old Stoney. He was a wise, old fish that lived in a stream only a few miles from my house. You’d be lucky to catch a glimpse of his wide shoulders and spotted back, much less to actually hook the monster. Still, the challenge of matching wits and ability against such a worthy adversary had me knee-deep in that creek for a couple of seasons during my youth. Was the elusive fish truly cunning? Was there an intelligence behind those unblinking eyes?
If you Google “Are fish smart?” a parade of articles and studies appears. Most pertain to aquarium fish such as goldfish and cichlids, and have to do with examples of associative learning, the process in which a new response becomes associated with a stimulus. Galaxias fish learn time-place association with feeding (where and when they are fed) faster than lab rats. Rainbowfish demonstrated light and sound associations even more quickly. Channel catfish retain sound association with food for years. I found one study on sharks very interesting – a lemon shark was put in a pool and trained to bump a board with a pattern on it to get food. If the board was bumped with no pattern or the wrong pattern, the fish was disappointed. After some time, the shark learned when to tap the board and when to ignore it. Next, a second shark was introduced and it learned very quickly how to get food by observing the first fish. The original lemon shark was removed and the second retained the training. This is known as social learning.

Channel catfish
Channel catfish retain sound association with food for years.

What does this mean about the fish we pursue? Can they learn to avoid a lure? In my grandfather’s day, every fish caught that was legal came home to a hot frying pan. Today’s angler has a different mentality and fish are released to be caught again. Catch and release, and selective harvest, are now the norm.

Catch and release is the defining factor in educating fish about angling. Being caught is a negative experience, especially for large ones. Small fish are quickly reeled in, unhooked, and dispatched back to the water. Giants are fought, landed with a net, and displayed for pictures before release. The longer a fish is out of the water, the more stress it experiences.

Most tournament anglers I’ve talked to don’t believe bass are intelligent. They use the term “conditioning” to define the lure avoidance behavior displayed by their quarry. Pro fishermen know a lure’s influence on the fish and act accordingly. That’s why they have multiple rods on deck rigged with different lures at all times. If the fish is conditioned or put off by one presentation, another may get a bite.

As much as every fish is unique in the niche it holds in the environment, it is unique in behavior and ability as well. In my experience, in the context of fishing pressure, some kinds of fish condition quickly while others don’t seem to learn at all. Catch and release of one fish species, harvest of another, and the basic nature of them all appears to dictate this. I’m going to concentrate on two species I’ve observed the most that are often the beneficiaries of catch and release, largemouth bass and striped bass. These are fish that seem intelligent when avoiding lures, but are they?

The simplest lure avoidance situation is contact with a hard bait. A largemouth bass that hits a hard bait (like a crankbait) but wasn’t hooked, will almost always avoid hitting it again. The fish has realized the lure is not food. Therefore, a tournament bass angler always keeps a soft-plastic lure rigged and ready to go. Even though the bass knows the hard bait is wrong, it’s not put off enough to avoid eating the soft bait.

Rat-L-Trap lipless crankbait
A lipless crankbait generates hard sensory cues like vibration and sound that are easily recognized.

The next avoidance situation has to do with lure characteristics. Let’s take the lipless crankbait, for example. This bait generates hard sensory cues like vibration and sound that are easily recognized. When used at the start of the season or on a lake that hasn’t seen one in a while, the bass hammer it. After exposure, they often want nothing to do with it, which is why manufacturers offer different rattles and designs. To stay one step ahead of the bass, fishermen try to disguise the familiar.

I conducted an experiment back in the 1980s that let me to believe that repeated exposure also drives an avoidance response. Fish-attracting scents were hitting the market and I wanted to prove to myself their legitimacy. I picked a large pond known for trout, but it was also a sleeper largemouth bass water. I used a black ½-ounce spinnerbait with a single Colorado blade. With four days of stable summer weather forecast, I planned to fish five hours each night, dividing time between the scented and the unscented bait. The first night, I landed almost 50 fish, with three over 5 pounds, so the scented bait out-fished the unscented. The results were the same the next three nights, but something else was going on. My overall success rate dropped each night and the sizes of the bass I caught dropped as well. The last night I landed seven bass, all small. I believe presentation saturation shut down the bass bite in a short amount of time.

Saltwater anglers are less likely to contend with conditioned fish because of the vastness and complexity of the environment and the migratory tendency of fish. But, here is a key point in my observation of one saltwater fish, the striped bass, when it enters the confines of the Connecticut River.

Stripers live in a wide-open environment, migrating for great distances and roaming shallow and deep. They are opportunistic feeders, eating anything from sandworms to shad, and I have never heard of stripers referred to as particularly intelligent. They willingly eat most lures, flies, and bait, rarely getting picky except during slack tide. But, in my experience, something happens to them when they enter a confining estuary and are put under heavy fishing pressure. Stripers get educated.

Connecticut River striped bass
Spring stripers in the Connecticut River are often looking up as they feed on river herring and shad. It’s an excellent opportunity to catch a big bass on a topwater lure.

From the late 1990s until about ten years ago, the striped bass run on the Connecticut was nothing less than phenomenal. Thousands of big bass migrated upstream to feed on river herring. I was fortunate to be a guide at that time and experienced it every day. The Enfield Dam was still mostly intact, so massive numbers of stripers were confined below the Massachusetts border. It sounds like fishing would be easy, but the pressure was intense—there were boats fishing live herring (which was legal then) everywhere you looked. The bass were exposed to this pressure daily and continuously. A fresh fish that just came upriver might fall for a badly presented bait, but the ones with some time under their belts became very picky. A striper would push a bait to the surface and track it, following right behind, so the leader and hook had to be invisible to the bass. If you tight-lined the bait, keeping it from swimming naturally, the striper would take off. On the other hand, we found that the same fish eyeballing live bait would crush a fast-moving pencil popper. No one was fishing them from boats.

Once the herring fishery closed, river anglers were restricted to artificial baits and fishing got tough. Running charters daily, I noticed that if the lure was presented with a mechanical, rhythmic action, stripers wouldn’t eat it. It was unnatural, and they knew it. Changing retrieves became necessary to entice stripers to strike.

There are times when fish are easily caught, the same fish perceive as intelligent, so instinct is to blame. It’s the driving force that gets fish to migrate, spawn, school, and feed. It is what makes a fish a fish. It’s also the issue I have with the intelligent fish concept. How can a fish be smart today and driven by instinct tomorrow? I don’t believe intelligence can be turned off.

largemouth bass
During the spawn, the largemouth’s drive to protect the nest at all costs overwhelms any fear of the boat or angler. Instinct says to stay put, guard the nest, and attack intruders even if an obvious threat exists.

Largemouth bass are a good example. The male of the species cuts a circular nest in shallow sand and gravel. When the time is right, a female approaches and the pair will not leave that spot until spawning is complete. As a result, sight-fishing for a bedding bass is very popular. You can see that giant bass, and it’s not going anywhere. It will aggressively defend the nest, often charging a lure when it hits the water. Some bass can be hooked and landed twice with the same lure on consecutive casts. The bass seem to have no control—it’s all instinct. The drive to protect the nest at all costs overwhelms any fear of the boat or angler. Instinct says to stay put, guard the nest, and attack intruders even if an obvious threat exists.

Striped bass also have their moments of uncontrollable instinctive drive that makes them easy targets for anglers. When blitzing schools of baitfish, the competition is intense, and the fish seem almost blind to their surroundings. Boats and fishermen are ignored, and bass gorged with bait continue to strike. When the competition’s hot, nothing else matters.

When blitzing schools of baitfish, the competition is intense, and stripers seem almost blind to their surroundings. Boats and fishermen are ignored, and bass gorged with bait continue to strike.

Do I believe fish are intelligent? I guess you can ascertain from what I’ve written that I’m a skeptic. The definition is, “the ability to acquire and apply knowledge and skill.” If fish, through exposure, realize a lure isn’t food and subsequently don’t eat it, is that acquired and applied knowledge?

I think that fish are different. We live on the same planet, but in different worlds. Fish have a complex suite of senses to perceive their environment and are highly aware. They are aware of fishermen and the lure, but I believe every fish can be caught.

4 thoughts on “Fish Intelligence

  1. Moe Miramonti

    Lamarckian evolution (which regulates gene expression across generations) would suggest all animals are “smart.”
    (Except for Trump voters- their only methylation is dirty farts)

    1. Ryan

      Moe seems to have a lot of time on his hands to look up this information, maybe you should find a job that doesn’t consist of watching CNN all day

  2. APEX

    How often have you heard comments on the stupidity of road killed animals? Think skunks, armadillos, possums, racoons, etc. We know they have the ability to learn yet they get flattened in vast numbers. Each of these species is acutely aware of their natural predators and have various defences and coping mechanisms to avoid danger. Cars are a different matter. Consider that none of these species evolved under pressure from traffic or the presence of roads. Are they too stupid to learn?

    Could fish be similar? Are they really stupid or are they constrained by their evolutionary state? I do some sight fishing for stripers in shallow water and see the young and dumb ones (small fish) will readily take a fly much of the time. The older (bigger) fish follow nearly as frequently examining the fly from one or two feet away. It is pretty rare for a big follower to lunge at the fly as it gets into shallow water when a smaller fish will frequently jump it before the fly “gets away”.

    We used to think trees were stupid. The growing evidence of tree communication and perhaps a more alien intelligence than most of us can imagine should make us cautious about passing judgement on the intelligence of any living thing. We have our own evolutionary blind spots and we are not as intelligent as we might like to think. Is it really any different for someone to fall for a con man than a striper to fall for a fly?

  3. Randa Wood

    Im worried about this fishing stuff-
    What do you know about it anyway-
    Let me tell you how to do it-
    Let me tell you
    How to live your life-

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