Why are some fish difficult to catch?

It’s all too easy to dismiss our quarry as lacking in brain power, but the truth is somewhat different. Here we reveal why some fish are able to outwit us...

Why are some fish difficult to catch?

by Angling Times |

Some days on the bank can be incredibly frustrating. Fish are showing in your peg and yet hardly a bite comes your way. How is it that so often we can be outwitted by a creature with a brain the size of a pea?

Let’s get one thing straight from the beginning. The oft-quoted tale that goldfish have a memory span of just six seconds is simply wrong. Anyone who has kept fish in a tank will know that they soon associate someone entering the room with being fed, and will often ‘follow’ you around the room hoping for a reward.

If fish had such a short memory then this behaviour simply wouldn’t be possible.

Fish memory

This leads on to the question about how long fish can actually remember things. In some cases the answer is probably their whole life, particularly with fundamental issues, such as being able to find their way to spawning sites.

Diadromous fish (ones that migrate between saltwater and freshwater), such as salmon, are an extreme example of this.

Atlantic salmon lay their eggs in freshwater headwater streams and the young fish spend their first years here before migrating out to sea to feed and grow.

They return as adults, not just to the same river, but to the same tiny stream in which they were born. This is an incredible feat of memory, and navigation.

While salmon may only spend a few years at sea, the mighty European sturgeon may roam the high seas for decades before returning to their home river.

As well as being among the longest-lived fish, sturgeon may well be contenders for the longest memory too.

It may be difficult to find such amazing feats of memory among our more familiar coarse fish. However, many species undergo long spawning migrations, and even shorter-term feeding movements, which prove that they can remember, not only where to go, but the layout of their environment.

How many times have you hooked a fish and it has known exactly where to head for the nearest snag? Even in the dark, fish can sense and remember their environment with an amazing degree of accuracy.

Fish can remember other individuals too. Tank tests have shown that fish prefer to shoal with other fish that they have associated with before, compared to strangers.

This behaviour starts at a very early age and, within a couple of days of hatching, fish learn and remember what companions they should be shoaling with, and which are a different species.

Salmon return as adults, not just to the same river, but to the same tiny stream in which they were born
Salmon return as adults, not just to the same river, but to the same tiny stream in which they were born

Avoiding capture

Few studies have been carried out looking at whether fish can learn to avoid capture, but one American report makes interesting reading. Pike kept in large pools were targeted using either artificial lures or with fish baits.

Once the pike had been caught once on a lure the chances of them being fooled again fell dramatically. Conversely, pike caught on fish baits were almost as likely to fall for the same bait again. If you’re a lure angler and you find your results tailing off then it may be that a change to a completely different pattern may revive your results.

Similarly, carp and other species of coarse fish will doubtless learn and remember by experience. So if they have been caught on a white pop-up, for example, they may well tend to avoid baits like this in the future.

Fish may learn by association, but this does not mean that they will always avoid capture.

When they are hungrier they may drop their guard and feed confidently, making them easier to catch, while at other times they may stubbornly avoid even the most subtle presentation.

Strong stimuli, such as a bright bait or an artificial lure, may lead to a stronger memory and more avoidance of hooks in the future than more subtle approaches – a fact that we as anglers should always bear in mind.

Once pike had been caught once on a lure the chances of them being fooled again fell dramatically
Once pike had been caught once on a lure the chances of them being fooled again fell dramatically

Recognising danger

Do fish actually have to be caught to associate something with danger? Perhaps not. Shoaling fish can certainly recognise the body language of their shoalmates.

If a roach on the edge of the shoal is suddenly alarmed by a perch stalking it, then this message will be almost instantly transmitted throughout the gathering. Their body language will change, with fins held erect and a nervousness among them that signals danger.

Could this alarm behaviour be replicated when a shoal of fish comes across us fishing? Perhaps a fish that has been caught before could suddenly become alarmed by a memory of a bait or rig and alert the other members of the shoal. There is little evidence for this behaviour, because it has not been studied, but it is not beyond the realms of possibility.

So it is no wonder that fish can become harder to catch the more they are fished for. This doesn’t just apply to low-stocked venues with specimen fish. Just take a look at how the fishing has changed on your local commercial fisheries, with new methods often working fantastically well for short periods of time before results slow down dramatically

Perhaps this explains at least one of the reasons why fish can sometimes be so difficult to catch.

Shoaling fish can certainly recognise the body language of their shoalmates
Shoaling fish can certainly recognise the body language of their shoalmates
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