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"Cod fishing.".

At this time of year lots of people fish for cod so I thought that a bit about fish senses (this stuff applies to allsorts of fish) might not come amiss. The cod fishers among you might also like to have a look at the tactics pages 37, 43, 87, 121, 131 and 145.

Your toes feel as though they have been refrigerated as you shuffle your booted feet on the wet, basalt ledge to check that their is still life below the knees. An icy breeze ruffles the oily, swelling surface of the water as it rolls up the ‘gut’ between the ridges of rock. Dusk approaches and the darkening sea surges between the waving fronds of kelp; twenty yards out in the gully your hook, liberally disguised by kebabbed mussels, rolls gently to-and-fro between the tangled holdfasts.

A sharp nod of the rod-top catches your attention and instantly the cold feet are forgotten. Knock, knock goes the rod again as you lift it from the rest.

The strike is met by a solid, plunging resistance and the nylon cuts sideways as you lift and reel to draw the fish through the clawing fingers of brown weed. You slide the 4lb codling on to the dark-grey rock and as you remove the 4/0 hook from the corner of the thick lipped mouth, you admire the perfect mahogany-red mottling of its back and flanks. Only another average rock-cod from a north-east-coast shore mark but, hang on a minute, lets look a little more closely at this common-or-garden codling.

How the devil did that chunky little fighter manage to find your half hidden mussel bait in the subdued---- almost non-existent----underwater, evening light? Are those big, wet, fishy eyes capable of seeing right through the tangle of inch-thick kelp stems? Are those little double nostrils really that sensitive? What part do the barbel, fins, skin and lateral lines organs play in guiding the coding bait?

Do the low frequency grunts of one hunting cod alert other fish in the area to the presence of food? To some of these questions the answers are still in doubt but several clues are available to suggest the sequence of events which are involved in the cod’s hunt for ‘grub’.

Cod and codling tend to be sociable fish, they often shoal in large numbers over favourable areas of sea bed and, at certain times may collect into large, compact schools for feeding or breeding. The fish in a school maintain contact with their neighbours visually, so that in poor light or turbid cloudy water they will pack closer together.

They avoid bumping into one another by sensing the vibrations in each other’s swimming movements through the lateral line---- in the same way they avoid scraping against kelp stems and barnacle covered rocks. Swimming prawns, Norway lobsters, cuttlefish and fish also give rise to vibrations which the cod can sense and track down. If visibility is good the movements of potential prey may be visible at some distance, as may the twisting and turning of other feeding cod.

The senses of sight and vibration-detection are only useful to the cod when the food is close enough to give out a detectable signal; at greater distances the sense of smell is the most useful. Like most other fish the cod has a ‘nose’ which is used only to sense chemicals dissolved in the water. On each side of the snout there are a pair of “nostrils”, water flows in through one hole and out through the other. Within the nasal chamber dissolved substances are recognised and the information is quickly received and computed by the brain. The cod then takes appropriate action !

A cod searching for food, particularly in dark or murky water, will try to economise on fuel by swimming with the flow of water. If the fish is in luck, and has chosen its feeding ground wisely, it may encounter a scent trail of substances drifting downtide from a suitable item of food. If you are well informed and have chosen your fishing mark with care, the item of food could be your bait.

If the bait lies to one side of the passing cod it may be possible to draw their attention in several ways. As I have already mentioned, they are most likely to catch sight of a large, contrasty or moving bait but only at fairly short range. Similarly, a vibrating, swimming or flapping bait or lure will increase the chance of it being found by the cod.

The best bet for attracting fish is obviously to send out a chemical signal from the bait or its general vicinity. Over the years I have tried several strategies designed to capitalise on the acute chemical senses of the fish and, like most such attempts, the results have never been sufficiently consistent to prove whether my tactics were effective or not! A summary might stimulate others to improve on my ideas (not all of them original of course).

Firstly, it seemed only sensible to make use of ready-made sources of attraction. Rough weather disturbs and injures many items of fish food and, inevitably, bait digging and collecting activities have the same effect. It may pay to fish over suitable ground which has, for example, been extensively dug on the preceding low water. To enhance or accentuate this effect it is possible to distribute reject-bait or other suitable attractants within the proposed fishing area. Scraps can be dug-in or wedged under rocks. It is sometimes suggested that groundbait may be placed in canisters or jars but there is already too much litter on our beaches.

Large baits will generally produce a stronger scent-trail than smaller ones and it should be an advantage to provide a large surface area from which chemicals will diffuse by slicing up or scoring the bigger pieces. Where long casting is not necessary it can be an advantage to skin or partly skin fish baits such as herring. It is undoubtedly, well worth changing baits frequently because the concentration of chemicals passing into the water decreases rapidly following immersion, a compromise between this and leaving a bait long enough to be hunted down is necessary.

With regard to the attractive properties of dissolved chemicals in the water, it is well established that the extracts of most of the common bait organisms will attract cod and some of them evoke a strong feeding response in the fish. The fish will detect quite tiny concentrations of a wide range of amino acids. These responses are by no means as simple as it might appear and Russian scientists have shown that while low concentrations of odours associated with the presence of other cod were attractive, higher concentrations had the reverse effect and repelled the fish. Such results may explain some of the strange observations of scientists studying the chemical senses of the fish.

Of course these are by no means the only things to take into account. I’ve written elsewhere about the fact that nothing makes fish feed better than the presence of other feeding fish. Finally, there is no substitute for being in the right place at the right time.

If you have any comments or questions about fish, methods, tactics or 'what have you.'get in touch with me by sending an E-MAIL to - docladle@hotmail.com

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