Tackle and Tactics
Mike Ladle

"HOME."

Information Page.

Flatfishes..

One of the trickiest tasks facing any sea angler can be introducing the kids to fishing. My own boys, when they were young, were always keen to “have a cast” but of course they were soon bored if no bites were forthcoming. It is essential to make sure that newcomers to the sport, young or old, have a good chance of catching something. There is no point in long campaigns to catch specimen fish or sophisticated methods that need weeks to perfect. Lots of bites and at least a few fish, however small and insignificant, are the order of the day.

From November onwards the tidal reaches of my local river seethe with flounders – from postage stamp size upwards – and these provide a perfect training ground for the up and coming sea angler. By casting ragworm on light leger gear five or ten metres out you can almost guarantee that within minutes the rod top will rattle to the pull of a flatty. A quick strike to make sure that the hook is not deep inside the fish and the line will sheer to and fro as another hand-sized specimen is reeled to the shore. Whether the sun is blazing down or the river is high in a dirty flood and even though there may be hordes of Sunday dog walkers or cyclists passing to and fro along the riverside path the flounders can be relied upon to cooperate.

Having been introduced to flatfish as “easy catches” or “fish for kids” it would be wrong to suppose that these curious creatures are somehow an inferior kind of fish. In fact the flounder and its relatives belong to one of the most highly evolved and sophisticated groups of fish in the world. Everyone knows that they are adapted to swimming on one side and that their eyes and mouth are twisted to fit their odd shape but perhaps it is less obvious that their search and destroy feeding equipment would rival anything designed by modern engineers.

The senses of feeling, taste, smell and sight are those which feature most strongly in the flatty armoury. All flatfish have two eyes on the upper surface and two “noses”, a small one on the blind side and a bigger one on top. Consider a couple of examples. The Dover sole is a master of nocturnal hunting. Creeping about the seabed in the hours of darkness or when storms have turned the water the colour of oxtail soup these bloodhounds of the undersea world have no trouble finding the tiniest morsel of worm on the blackest night. How do they do that?

Experiments in Holland have shown that the sole sniffs out prey which is lying quite still on the seabed by using the nostrils on its eyed side. If these are plugged to prevent the flow of water to the “nose” the fish have great difficulty locating prey. However, the sole has another trick up its sleeve. The furry touch sensors on the blind side of the head allow the fish to feel for its prey on the seabed. Recent studies have shown that the nocturnal sole has ten times as many “smell sensors” in its nose as the day time feeding plaice and three times the area of “smelling” tissue. No wonder sole will ignore food dangling above their heads as they search the surface of the sand for shrimps.

Both plaice and sole feed on worms, shrimps and small clams but the plaice depends much more on its eyes to locate the prey. Smelling and tasting food is a great deal less important to the plaice than the sole. In fact the section of the brain used for smelling food is much smaller in the plaice than in the sole and the reverse is true of the section concerned with vision – hence the benefit of beads and spoons as attractors for plaice, flounder and similar species.

Scientists have used special chemicals which temporarily knock out particular senses to find out exactly how flatfish locate their food in daylight and in darkness. Video cameras allowed the behaviour of the drugged fish to be watched. Both plaice and sole were able to feed – day and night. However, when the sense of touch had been numbed sole had difficulty catching live prey but were still able to find dead food. Knocking out its touch sensors made no difference to the hunting ability of plaice but the old spotties were not very good at feeding in the dark anyway and they would often mouth food items before spitting them out.

On a slightly different tack, most anglers are aware that flatfish come in right-eyed (like the sole and plaice) and left-eyed (like the turbot and brill) varieties. The side which has the eyes develops camouflage colours allowing the fish to hide on the sea bed while they are hunting. In the past it has been suggested that the fish were able to improve their camouflage by imitating the background pattern. For example, some experiments in 1911 seemed to show that a flatfish could change colour, over a period of days, to imitate a chess board pattern. More recent studies have suggested that this work was wrong and that the results were due partly to photographic problems.

Recently scientists in California set out to answer the question once and for all. The showed that not only could flatties blend into the background with ease but they could mimic checker-board patterns in a flash (2-8 seconds), a speed which would put the famed chameleon to shame. Tropical flatfish were much better at this colour change than our own cold water species. They were even able to “copy” big polka dot patterns by producing two large dark spots on the skin. The precision and fantastic speed of these changes suggests that the fish sees the pattern and its brain instantly signals the message to the pigment cells in the skin – a trick which, as far as we know, no other animal (except possibly some squid) is able to do.

Anyway, next time you are down at the coast and your mate reels in a flounder, dab or plaice don’t say “it’s only another small flatty!" and rip it off the hook. Handle it carefully, like the marvel that it is, and return it to the sea to grow bigger and fight another day.

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

INFORMATION SPOT

Flatfishes.

Index