The Lateral Line Changing the Game
In a break from the norm, Ivan takes a far MORE SCIENTIFIC APPROACH TOWARDS OUR QUARRY AND HAS A LOOK AT SOME OF THE WHYS AND WHEREFORES INVOLVED IN BETTER UNDERSTANDING THEIR BEHAVIOURAL HABITS…
In a break from the norm, Ivan takes a far more scientific approach towards our quarry and has a look at some of the whys and wherefores involved in better understanding their behavioural habits...
YHEou’re at a party and the host says, “Have you met Bill (or whatever his name is)?
fishes.” And you think to yourself: thank heavens for that, the chap talking to me was chewing my ear off! “Talk later” you say, (but you probably won’t), “I’m just going have a quick chat with William”.
Three and a half hours later (he fishes for the same species as you do), you and your new best mate are into the heart of fishing: the sneakiest tweaks, the finest rigs, secret baits – the Campari and sodas have really been flowing. We’ve all been there, and it’s great when that happens, but when he was attributing his successes to ‘Fire Pattern Theory’, you thought - Qué?
We know that the most ardent anglers are sorted in terms of their tackle, tactics, techniques, baits, venues, rigs, not to mention approaches but there’s something missing from this list that isn’t tuned to the same degree: the game, think like a fish. We do ponder this, lose sleep over it even, but typically we are anthropomorphising – that is to say humanising the situation: we like to think what we would do if we were the fish, which can only get us so far. What if you knew how a fish processed information on top of this instinct... what could that do for your fishing?
Mount Everest is 29,029ft high, and I reckon specialist carp angling has come 29,000 of those feet but there’s still 29 feet to go – and that level takes us to the category of the super-specialist! This is opinion admittedly, and Clint Eastwood, as Callaghan, said of opinions, “They’re like ar*eholes. Everyone’s got one!” However, I believe this ‘push for the summit’ is worth exploring.
If you pursue the most pressured, biggest, oldest, wisest fish, and you consider that fish intelligence can and does have a bearing on fishing, then this article’s for you. If not, in the nicest possible way, have you seen Dirty Harry?
Don’t look for offerings that will do for your fishing what wood to carbon did for rods, or catgut to monofilament did for lines? Those leaps are done. As we’ve got better and better at what we do, improvements have gotten harder and harder to come by (a bit like a sprinter trying to knock a hundredth of a second off his 100m PB), but whilst these advances grow ever slimmer, they arguably increase in their significance?
The question is does knowing something about how a fish processes information help us when pursuing pressured, old and wise leviathans?
This extends to considering an angler’s intention to catch the main members of an apex pod and asks if it comes down to something more than just luck: more than a matter of maximising the ‘dos’ and minimising the ‘don’ts’.
You may already fish in a way that outwits the fish’s processing capabilities, without knowing it – not implausible, albeit that you might not be
able to explain how and why your methods work. So what, you simply fish in a way, coincidentally or otherwise, that accounts for ‘fish intelligence’? But then again, maybe you don’t?
In this article we delve into the brain of the fish to consider how it works and what, if anything, knowing about these things can do for our fishing. It’s a heavy subject, but one that I’ve simplified (whilst trying to remain true to the science of course). It assumes that we can all be a ‘Baldrick’ from time to time, but credits us with Plato-like powers of thought as well. It goes without saying that the scientists among you will probably squirm with my examples, which is not intentional. Put the kettle on and let’s get to it.
If you’re like me, it’s probably taken you a lifetime to amass all you know about fishing. If you had to teach a beginner all that knowledge, the things such as knot tying, line strengths, rod test curves, etc. would be easy to teach, but you can’t know fishing by looking at these things – that’s like trying to understand English Literature by studying ink.
Fishing’s more than its ‘mechanistic’ parts, just as fish aren’t mere ‘net visitors’. How we talk of special captures, or what it is to be ‘moved’ by nature’s wonder are the things that get us closer to the essence of the pursuit.
Just as the setting of an idyllic lake is comprised of elements (the sun, trees, birds, etc.), viewed not as individual items, but as a ‘whole’, so by de-constructing our quarry, to see what elements comprise them, we should be able to better understand them.
Enough big talk! The intelligence of our fish is as a direct result of our fishing for them: they are A.I. – ‘angling intelligent’, and can learn to recognise certain angler-related hallmarks and avoid capture under certain conditions.
Avoiding capture is to be differentiated from
when we say we ‘lost’ a fish. A ‘lost’ fish is one that was hooked (past tense), but you didn’t get it in the net – you lost it. Avoiding capture is different: it is to evade or even escape the hook, moreover, and is done so by something more than sheer coincidence/luck and importantly, you may never know if and when this happens!
This start position grants that a fish can avoid capture (emphasising the phrase ‘under certain conditions’) and it is fine if you don’t agree with that statement. The cyprinid has a sophisticated ‘circuitry’: a nervous system that travels around its body like the wires of a circuit board connecting things up. At the terminus of all this ‘wiring’ is the brain! Messages sent to the brain are ‘afferent’. Messages sent from the brain are ‘efferent’. Afferent messages are sent from the senses to the brain for processing. Efferent messages are processed to the point that they trigger movement. In fact, in fishing terms, they can result in ‘nothing’ (i.e. there is no obvious action), which sits between ‘eat’ and ‘avoid’.
For an action to be triggered (the correct term is ‘elicited’), a change in the environment must stimulate one or more of the senses. Fish receive multiple stimuli, which as we will see, can vary in significance.
Take sight. As the fish moves around its environment, its eyes scan the world forming mental representations (internalisations) of the scene. Do you remember the old cine films? They came on reels and made a flickering sound when they played. If you’re too young to remember these, what about those drawings you sketched at the bottom of your maths book: when you flicked the pages they appeared as a cartoon? The film was made of individual frames (the cartoon, of individual pages) but only when ran at speed (or in the case of the book, flicked) would they create the illusion of movement. Each new frame of the film, or sketch in the book, represents the ‘latest, most up-to-date’ version of what you are seeing – it is a continually refreshing view.
The fish is doing something similar, in the sense that its eyes are capturing (‘apprehending’) anything that they see and discern, and we need to give this phenomenon an angling term. In this instance, in the case of vision, it is a Retino-tectal-projection. (Retino, as in retina (i.e. of the eye), and Tectal, as in Tectum, the region of the brain that specialises in processing visual information. Literally, an eye-brain-image or brain-eye-image, whichever you prefer.)
Because information sent to the brain streams in from more than just the sense of sight – for example, messages can be chemical in nature, or carry water-borne information, etc., the projections can be thought of as ‘sense images’ or ‘sense projections’.
The eyes then scan the world, sending visual data to the brain, data such as shape, size, colour etc. When a piece of visual information reaches the brain, let’s say ‘shape’, it is directed to the place that deals with, yep, you’ve guessed it, shape. Similarly, information about movement or a chemical cue is directed to its corresponding region of the brain for processing.
The job of directing incoming data is the role of specialised brain cells called neurons that reside within their specialised regions. Visual information, for example, is directed by ‘tectal neurons’, i.e. neurons embedded in tectum, and there are 15 known different tectal neurons in cyprinids, responsible for a range of operations that we’ll come to.
Let’s summarise so far: the senses get stimulated. They stream information into the brain. The information can be differentiated by which sense it relates to, so that data picked up by the eyes (visual info) connects to a specific region of the brain that deals with visuals; data picked up by the chemo-receptors (chemical info) connects to a specific region of the brain that deals with chemical processing, and so forth. The specialised neurons within these specific regions, link to other parts of the brain in order that ‘full’ processing can occur. Fully processed information reaches the motor centre where an efferent signal will elicit an appropriate action (‘eat’, ‘avoid’, ‘nothing’).
The highly specialised nature of these brain cells, and their connectivity to other areas of the brain, means that a visual message cannot be processed in a region of the brain that deals with say movement, nor a chemical message be processed in the region of the brain that deals with say visuals. The ‘wiring’ makes that impossible. You can’t flick the downstairs kitchen light on, and
the upstairs bedroom lights go off, (well, I do know an electrician called Dave who...). This means that an action cannot be inappropriately elicited: The brain of a healthy roach for example would not instruct ‘eat’ when perch loom into view. Apart from the fact that the shoal flee every time large, two-tone, ‘moves in certain ways’ creatures appear on the scene. To stay behind when your shoalmates have gone, assuming this doesn’t confuse the perch of course, is only going to happen once, and your flawed brain circuitry will then have been removed from the gene pool!
It is simply the case that young fish, in this instance, roach, learn very quickly what two-tone, ‘moves in certain ways’ creatures, means, because if you don’t... you’re brown bread! On the subject of learned predator avoidance; if you happen to be in the business of stocking fish, please speak to me first.
However, and it’s a big however, in terms of trying to persuade a big old, wise carp to take a hookbait, this does not mean that you cannot lead the brain to elicit an action that you are trying to make happen.
Note the word ‘lead’ here, not ‘fool’ or ‘trick’, because to fool or trick, is to attempt to deceive the brain into doing something that it could think it shouldn’t be doing, and this is to incur risk – not ideal when fishing for a once in a lifetime fish.
To think of angling as fooling fish is not mistaken, but when it is through the deployment of methods that have worked previously, particularly when you haven’t considered fish intelligence before, this is not exacting enough. It is precisely because something has worked more than once that the potential for risk arises in the first place, and this runs to luck more than it needs to. Keep in mind that we are pushing for the summit – entering so-called super-specialist territory!
If you’ve got a list of most desired fish to catch before you leave your body behind, why employ a tactic that has a degree of risk in it when there are tactics you can employ that impart less risk, or if you prefer, appeal less to chance? To lead a fish implies that all associations and communications have been removed not lessened. You keep the recognisables you want, and remove the ones you don’t. (I presented this as a plausible explanation for Beginners Luck Phenomenon).
Imagine it’s daylight, clear water, and a wriggling worm has caught the carp’s eye. The eyes are stimulated and the brain cells become ‘excited’. A projection takes place, in this case a retino-tectal-projection.
Note that whilst the sense in this example is sight, the feature actually being observed is a characteristic of movement, namely, seeing the ‘wriggle’. The look of the wriggling worm, where it can be seen of course, is combined with the feel that wriggling makes in the water as detected by the lateral line, and any smell, as detected by the chemo-receptors, as well as other things of course, for example, locational cues. (How often the fish has experienced a wriggly worm, and thereafter how many of those experiences were positive or negative, and over what time period, are questions we will be considering). Seeing the wriggling worm causes the brain cells of the tectum to become fired-up, or activated. You know that if tectum is being activated, it must be a visual stimulation that took place.
If sight was not possible, for instance the water was too murky, or it was night, and the fish sensed
the wriggling worm via the lateral line organ only – i.e. it ‘felt’ the wriggle; that sense would project to its corresponding region of the brain, where its cells would fire-up. If you know what region of the brain is being activated, you can know what sense it relates to.
The lateral line is a sophisticated sense and can report a great deal of information to the brain: depth, pressure, temperature, orientation, current, identification of shoal members, threat and prey recognition, coordination, maintenance of distance, sense of speed, direction, courtship ritual – the list is long. Here, we concern ourselves with the ‘water-borne hallmarks’ that trigger feeding (which includes the behaviours of creatures other than fish – for example, crayfish, tadpoles, ducks, etc.), and the ‘bolt signature’, i.e. that which the lateral line knows so well. We also give thought to depth signature, especially when there is an over-fishing of certain places.
Back to the ‘firing’... The phenomenon by which brain cells ‘fire-up’ has a number of terms; population coding, distribution pattern and more, and can be thought of as the specific population of brain cells that activates in response to a specific afferent (inbound) message. It’s a bit like those images you’ve probably seen of a human brain that ‘light-up’ when we think certain things. The point is, each time we think that certain thing, the same area lights up. Conclusion: certain parts of the brain are responsible for certain things.
Now combine information sent in from the eyes with the information sent in from the lateral line organ, from the chemo-receptors and so forth, and then add in size, shape, colour, etc. and we quickly identify a number of detectable features that our wriggling worm can possess.
Pause for a second! How many features are needed, before you can discern what it is that you are sensing, is what you are sensing? In other words, what is the minimum number of features you need before you can ‘know’ what it is that you are sensing? Key question!
Consider that some features rank higher than others, and in addition, fish may depend on different senses for different situations, for example those of super-clear habitats may have pronounced sight, whereas those of turbid habitats may have pronounced ‘chemo-detection’ etc.
We address these questions under specificity coding, and hierarchical processing, which exist as phenomena and appear to give preference to some features over others, especially in the threat circuitry.
We know that a small black thing on the surface of the river for a trout is ‘go-get’, just as a long thin thing that moves is ‘goget’ for a toad. These features are ‘species specific’. Note that a toad will stare at a motionless worm and be unresponsive, but as soon as the worm moves – it ‘snaps’! Worm grunting is another, a good example of how a ‘feature’ (in this case, vibration) causes worms to come to the surface immediately when a notched stake, driven into the ground, is ‘raked’.
Similarly, when a large black spider runs near your foot and you don’t make it out at first, but when you do, you jump out of your skin! You’re programmed to react to these features, for example, long legs and the way in which they move!
If it were the case that all features of our worm needed to be detected before a decision could be made, a dead worm wouldn’t be taken in clear water (because the wriggle wouldn’t be felt) and a wriggling worm wouldn’t be taken in murky water (because it couldn’t be seen), which isn’t the case.
It only requires a minimum number of key features to be detected before a fish can make a positive identification, and a positive identification in this context means ‘definite decision made’ and applies to situations that may result in a negative response!
In light of the idea that a fish’s senses may vary in terms of their dominance, and as anglers we may appeal to specific senses, plus the notion of feature ranking – i.e. the idea that some features rank more favourably than other others, when we consider the past experiences of the fish and the past practices of the angler – you can see how the number and type of key features can vary from situation to situation. Paying attention to this idea, will outtrump anyone practicing ‘staythe-same’ methods.
We know that visual processing takes place in its own specific region of the brain, as does olfactory processing and so forth. When information streams in from a number of different senses, the department of the brain that ends up commanding the ultimate action is the one that has the strongest correlation with a past experience (experience – memory).
Let’s summarise again: The senses get stimulated, they stream information into the brain. Information from the senses goes to their specific regions of the brain for processing. Specialised neurons direct the incoming info. Specific populations of brain cells in their respective regions ‘fire-up’ to form internalisations, or ‘fire-patterns’, either from a single, key feature, where there is a strong correlation (positive or negative), but also as the result of a combination of key features, again recognisable, or not. An appropriate response will be elicited (eat, avoid, nothing).
We can reduce these ideas to over-simplified expressions:
VFP wriggle: visual fire pattern – wriggle: wriggling worm ‘seen’, projection by the eyes to brain region A, causing firing pattern X.
LFP wobble: lateral line fire pattern – generated by the wriggling worm in the water: worm ‘felt’, projected by the lateral line to brain region B, firing pattern Y.
CFP smell: chemo-receptor fire pattern – the smell of the worm: projected by the olfactory sense to brain region C, firing pattern Z.
We know that visual processing takes place in its own specific region of the brain, as does olfactory processing and so forth. When information streams in from a number of different senses, the department of the brain that ends up commanding the ultimate action is the one that has the strongest correlation with a past experience
To complicate things further, these fire patterns (the specific set of brain cells that fire in their particular regions to a specific afferent) may overlap. This could be due to situations where there is a lack of a clear cue, or information?
As information streams in, key data ends up triggering a response, but where that key data has been previously encountered, FPT, or fire-patterntheory enables us to grapple with the beginnings of how experience, memory and learning occurs in fish.
When a wriggling worm has been experienced many times (without a negative outcome), the associated sensory circuitry also fires many times. The fish came to know the ‘thing’ they are sensing by way of the development of reliable ‘internalisations’, i.e. the ‘fire patterns’ that are generated each time the worm is experienced and the corresponding resultant action is the same. The repetitive and constant ‘firing’ of the circuitry leads to a process of synaptic plasticity: the strengthening of the circuitry as the result of its continual and repetitive firing. It predisposes the circuitry to ‘fire’ more readily at the next experience where things are the same. We can say that the worm’s key features trigger specific circuits over and over, and in doing so renders those circuits ‘SP High’ (i.e. they have a high synaptic plasticity), that is, they are ‘wellfired’, ‘burned-in’, ‘engrained’. The worm becomes recognisable to the fish because the key features cause a repetitive firing of the same circuits, which in turn triggers the same outcome.
What can we reliably say? Fish have senses. They send afferent messages to regions of the brain that deal with specific sense data. Specialised brain cells, in those regions, re-direct the incoming info in order that it is ‘assessed’ (shape, movement, size, colour etc.). The checked data leads to ‘internalisations’ – specific populations of brain cells ‘firing’ in their respective regions. When the circuitry involved in these internalisations repeats many times, within a certain period of time, a process of synaptic plasticity takes place. The regular encounter of these specific stimuli leads to the circuitry becoming ‘SP high’, and, so long as the outcome is a constant, and the associations between those key features and their corresponding outcome remains the same: recognition takes place and events become predictable/knowable.
Next, we look at ‘distribution circuits’: what these are, what they do, and why and how they matter to our fishing. Until next time...
ABOVE Autumn gold TOP LEFT A nicely proportioned fish BOTTOM LEFT THE BENEFITS OF BEING AN ARBORIST
ABOVE Coaxed into a legal, YET UNFISHABLE SWIM
ABOVE A beautiful old fish