Lemon sole Microstomus kitt

Distribution

Like plaice, the lemon sole (Figure 9.19) is a flatfish of shelf areas of the north-east Atlantic ranging from the Arctic to the Bay of Biscay. It does not extend as far south as plaice and generally favours a rougher sea bottom, but the two species often occur together. Lemon sole are specially abundant in the north-west part of the North Sea off the east coast of Scotland, also around the Faroes and along the south-west coast of Iceland and these are the most important fishing grounds (Figure 9.20). It is most common on gravelly bottoms but may occur on any substrate. It lives mainly between 40 and 100 m but is found in reduced numbers to nearly 200 m. The fish are caught mainly by trawls and Danish seines.

Life history

Unlike the plaice, the lemon sole does not have well-defined spawning grounds, but simply spawns widely throughout its range, gathering in small local concentrations wherever the fish are normally found. Tagging experiments have indicated a tendency for the fish to swim against the current during the period

Lemon Sole Skin Photos

Figure 9.19 The lemon sole, Microstomas kitt. Identification features: 1 = Colourful speckles on smooth slimy skin with no bony tubercles; 2 = Only slightly curved lateral line.

(Modified from British Sea Fishes, F. Dipper (1987), by kind permission of Robert Irving and Underwater World Publications Ltd.)

Figure 9.19 The lemon sole, Microstomas kitt. Identification features: 1 = Colourful speckles on smooth slimy skin with no bony tubercles; 2 = Only slightly curved lateral line.

(Modified from British Sea Fishes, F. Dipper (1987), by kind permission of Robert Irving and Underwater World Publications Ltd.)

preceding spawning. In the north-west North Sea this results in a limited northerly movement towards the Orkneys and Shetlands or westward around the north of Scotland, but there is no great spawning migration. The fish do not appear to require very precise conditions for spawning. In the North Sea it takes place mainly at depths between 50 and 100 m when the bottom temperature is not lower than 6.5°C. Around the British Isles the earliest spawners are usually found in the English Channel in February or March, with a maximum abundance of eggs in April to June. Spawning off the west of Scotland extends from March or early April until late July with the peak in April to May. In the North Sea, spawning begins in the north in early May and a little later further south, with a maximum in June to August, and lasting into November in the central North Sea. Around the Faroes and Iceland spawning lasts from May to August with the peak in June to July.

Lemon sole eggs are smaller than plaice, 1.13-1.45 mm in diameter, and produced in rather greater numbers per female, some 80 000 to 700 000 depending on the size of fish. They are probably shed on the bottom, but float to the surface for two or three days before sinking back to middle depths. Hatching takes place after some six to ten days depending on temperature, and the emerging larva and yolk-sac are symmetrical and about 5 mm long. The mouth and gullet are narrow, allowing only small food objects to be taken, such as eggs,

Microstomus Kitt

Figure 9.20 Distribution and main concentrations of lemon soles, H light, ■ moderate, ■ heavy.

(From Rae (1965), by courtesy of Fishing News (Books) Ltd.)

Figure 9.20 Distribution and main concentrations of lemon soles, H light, ■ moderate, ■ heavy.

(From Rae (1965), by courtesy of Fishing News (Books) Ltd.)

peridinians, diatoms, Podon and copepod nauplii. Later larvae also eat Limacina and Oikopleura.

Although the larvae can be taken in tow nets at all depths, the majority are near the bottom and few are found close to the surface. In the north-west North Sea the drift of eggs and larvae is southwards towards the central North Sea. The pelagic phase lasts some two to three months, terminating with a metamorphosis similar to plaice, after which the fish live on the bottom.

Lemon soles take a wide variety of food from the sea floor, but the major part of their diet is almost always polychaete worms, especially the eunicids Onuphis conchylega and Hyalinoecia tubicola, the terebellids Lanice conchilega and Thelepus cincinnatus and several serpulid species. Their diet is restricted by the small size of the mouth. The anemone Cerianthus is an important food in some localities. A variety of small benthic crustacea (mainly amphipods and eupagurids), molluscs (mainly chitons and small gastropods) and some ophiuroids are also taken. Small bivalves are eaten and the fish bite the siphons off larger lamellibranchs; but compared to plaice, bivalves form a much smaller part of the diet of lemon soles and it is unlikely that the two species compete much for food.

Lemon sole grow rather slowly attaining about 15 cm in length at the end of their third year and 25 cm by the end of the sixth year. However, the western North Sea off the British coast between Yorkshire and Aberdeen is a region where they grow relatively quickly. Here the lengths at these ages are nearer 25 and 30-35 cm. The fish can grow to nearly 50 cm and rare specimens have been caught between 55 and 67 cm, probably at ages between 15 and 20 years. The majority age of first spawning is four years for males and five years for females. Like several other species, after maturity the males have a slightly greater mortality rate than females so that in the older age groups the females progressively predominate.

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Renewable Energy 101

Renewable Energy 101

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Responses

  • Jana Weisz
    Why lemon sole ecology?
    8 years ago
  • seren
    What is lemon for ecological grow and use and how to sole?
    3 years ago

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