To commercial fishermen, the plaice is the most important flatfish species. Abundant, readily tempted with the right bait, and delicious to eat, it’s just as popular with anglers.
Of all the fishes caught around the British Isles, few are better known than the plaice (Pleuronectes platessa). It has long been a favourite with the housewife as it looks very attractive when displayed on fishmongers’ slabs with its eye-catching orangered spots. The plaice belongs to the order of fish known as Heterosomata, which means ‘twisted-bodied’. These are the flatfishes which swim on one or other side of their body just above the sea bottom.
The plaice lies and swims left side down. The colouring of its right or upper side varies from a light sandy brown right through to a dark brown according to the locality and the type of seabed on which it lives. The distinctive spots, too, range in colour from pale orange to bright scarlet. Furthermore, if the seabed is chalky, then it is not uncommon to catch plaice with white spots as well as red. The underside, however, is always a translucent bluish white with thin blue streaks.
The skin of the plaice feels completely smooth when rubbed with the finger, although there are several bony knobs on the ridge of the head which distinguish it from other flatfish. The lateral line is very slightly curved in the vicinity of the pectoral fin, and the jaws are lined with very strong teeth. There are also muscles resembling a second set of jaws at the entrance to the gullet, which are used to crush small varieties of shellfish.
Plaice are found all round the British Isles, extending northwards as far as Iceland and as far south as the Mediterranean. Spawning takes place very early in the year—usually in January or February—in depths of 15-30 fathoms. The eggs float in the sea and measure approximately IT, inch in diameter. A good-sized female, a fish of, say, 3 lb, produces as many as 250,000 eggs in one spawning. Depending on the water temperature, the eggs take anything from 8-28 days to hatch. The newly hatched larvae measure about in, and at this stage are not flat but rounded like other fish.
The larva feeds on its yolk sac for about the first week of its existence and normally not until it has ex-hausted this food supply does it change from its original round shape to the flat shape it will have for the rest of its life. At the same time, the young plaice begins to take in food, which at first, of course, is of microscopic dimensions.
The fish’s change in shape begins with a change in the position of the eyes. The left eye moves upwards and forwards and after about ten days arrives on the upper margin of the head just in front of the right eye. A little over four weeks later it reaches its final position above and in front of the right eye. While the eyes are going through this rotating movement, the young fish begins to take up a new position when swimming. As it has been growing, the whole anatomy of the body has gradually undergone a distinct twisting process, and the fully developed fish finally swims and rests, camouflaged, on its left side with both eyes pointing upwards.
The growth rate of a plaice, though relatively fast for a flatfish, is slow when compared with that of cod, for instance. A four-year-old fish will measure only 12-13in, although this may vary slightly from area to area.
Females mature some time between their third and seventh years, when they are about 9-1 lin long. Males mature a year earlier, between their second and sixth years.
The early life of a plaice is spent in sandy shallows feeding on very small crustaceans called copepods and large quantities of mollusc larvae. After about six months of this diet the fish attain a length of some 2in, and at about this size they gradually move farther out from the shore, although they still favour areas where the depth is less than five fathoms. Tagging experiments have shown that plaice do not as a rule travel a very great distance, usually staying close to their spawning area throughout their adult life.
There is one fish on record that was tagged in the North Sea in 1904. It was recaptured in 1920 only a few miles from where it had originally been tagged.
Adult plaice return to shallower waters near the shore in March and April to recover from the rigours of spawning. At this time they are thin, but after a few weeks of feeding in the rich shallows they quickly regain weight. The adult fish feed mainly on bivalve shellfish of all kinds, small cockles and mussels being firm favourites. The mussels are swallowed whole and are crushed by the jaw-like muscles in the throat; the fish then digests the contents and excretes the pulverized shell.
If there is ample food, plaice will frequent almost any type of seabed. Some of the best catches are taken in very rocky areas where they are usually feeding on mussels growing on the sides of the rocks. On sandy seabeds they search out razorfish and they will even travel up estuaries in search of cockles and other bivalves. They will eat marine worms, such as lugworms and ragworms, although these do not seem to figure very prominently in the plaice’s natural diet. Therefore, it is not surprising that, although trawlers catch great quantities of plaice, rod and line anglers fishing the same area with marine worms usually fail to make big catches.
The most likely area to take plaice on rod and line is on mussel beds—but the mussels should be smallish, no bigger than an inch in length. Mussel beds appear in different areas from year to year, and they are usually located by accident, but once found it is reasonably safe to assume there are plaice to be caught there in good numbers.
The ideal time to try for these ‘flatties’ is during prolonged settled weather in the summer. Clear water and bright sun make for better fishing. As the fish feed largely on bivalves, one would assume that these would be the best bait, but for some reason they seem reluctant to take them when they have been removed from their shells; and of course it is totally impractical to try to hook the mussel while still inside its shell. Thus the angler is reduced to using less favoured, but nevertheless successful, marine worms as bait. Lugworm usually proves the best, with ragworm running a close second, although this order may be reversed in some areas. Peeler crab, too, is often used.
Plaice do not grow to great size and the rod-caught record is a fish of 10lb 3£oz, boated by H Gardiner fishing in Longa Sound, Scotland in 1974. Professional trawlers frequently take bigger fish than this, often well into double figures, but | the rod and line angler can usually count himself lucky if he takes fish I in the 3-4lb range. For this reason a light hollow glass rod in the 20lb class is to be recommended, pro- | viding leads of over 12oz are not going to be used.
For terminal tackle a trace should be used when the tide is running, but paternoster gear is favoured on sluggish tides or slack water. If using a trace, it should be about 8ft in length, either fished through a Cle-ment’s boom or a Kilmore boom. If baiting with lugworm, a long-shanked hook, No 2 or 1, is quite large enough. Use three hooks together, as more than one fish is taken at a time quite regularly. This is often because, even if you are holding the rod when the plaice swallows the worm, no bite is detected due to them swallowing the baited hook and remaining still. It is only when you lift the rod tip that you realize that a fish has in fact taken the bait.
Fish caught like this are usually deeply hooked. If, however, a bite is felt it is usually only a light tap, tap, and should be left for the fish to gorge the bait. To avoid the temptation of striking too soon, it is best not even to hold the rod.
To attract the fish, white spoons may be added to the trace, but they must be celluloid and not metal. Celluloid spoons are lighter and even a slight tide will give them movement in the water, and it is this movement that entices flatfish to attack the baited hooks.
A different method of fishing should be used when using paternoster gear on slack water. In these conditions, the rod tip should be continually raised and lowered. This has two effects: first, it gives the bait movement; second, every time the lead strikes the seabed it sends up a cloud of ‘dust’ which, because plaice are very curious creatures, brings them close to the baited hooks to investigate. Fishing this way, the bite is very positive, being more in the nature of a sudden snatch rather than the gentle tap experienced with a trace. Unlike a bite on a trace, the sudden snatch should be struck immediately. Once hooked, the fish dives for the seabed and on light gear can put up quite a lively fight, diving for the bottom all the way to the boat. A landing net should be used in preference to a gaff for the bigger specimens.
Although plaice generally favour deeper water than other flatfish such as dabs and flounders, good fish can also be taken by shore-based anglers. However, whereas boat anglers will often go out and fish specifically for plaice, plaice taken by shore anglers are more often caught by accident. The most likely areas for shore plaice are river mouths, particularly those of Devon and Cornwall. Notable fish can be caught from the shore, too. A former record fish weighing 7lb 15oz was landed by a youngster fishing at Salcombe, Devon.
Estuaries and bays
When fishing for plaice in estuaries, the baited spoon method is the best. By slowly recovering line the bait is kept on the move, so preventing attack by the crabs which abound in this kind of area. In addition, the spoon, as it revolves, flashes and disturbs the seabed, attracting fish to the area. As well as estuaries, other likely shore-based spots are sheltered sandy bays with a fair depth of water, and rocky shores with sandy gullies. For the latter, a paternoster rig is recommended, the terrain being too rock-covered and snaggy to use a spoon.
Plaice make excellent eating. A fish of over 2£lb can be ‘quarter filleted’. To do this, cut through to the bone from head to tail along the lateral line with a sharp knife and then carefully remove the flesh from the bone by cutting outwards towards the fins. Do this on both the top and the underside, thus making four good fillets. A fish in good condition will produce half its total weight in fillets.