Grayling Thymallus thymallus; Linnaeus, 1758. Family: Salmonidae
Photo R. Calbrade, The Grayling Society
The grayling (Thymallus thymallus) is a species of the salmon (Salmonidae) family, and is found mainly in rivers. It is readily distinguished from other salmonids by the large dorsal fin and quite large scales. It is often silvery, or grey in colour (hence the name), although mature fish can be darker, particularly the males around spawning time.
Grayling spawn in river shallows where there is fine gravel and moderate current speed in spring. The eggs are quite small, measuring about 3 mm in diameter, and hatch after two or three weeks.
When the larvae emerge from the gravel they are 12-18 mm in length and may seen swimming in shoals near the surface in quieter water, close to the bank. In favourable circumstances grayling grow quickly and can reach 30-40 cm by the time they are three years old. In later life, their growth rate slows down, and the maximum length reached is usually between 35 and 45 cm.
Diet and Feeding Behaviour
Grayling feed mainly on insects and their larvae, crustaceans such as freshwater shrimps, and worms, leeches and molluscs. In winter, salmon and trout eggs may also be taken. Feeding is by intercepting material drifting downstream either mid-water or on the water surface and by grazing over the bed and any strands of vegetation.
Habitat and Distribution in Scotland
The grayling is native to parts of England and perhaps Wales, and was first introduced to Scotland from the Derbyshire Wye 150 years ago. It is now present in many rivers of the central and southern parts of Scotland, and can be the dominant fish species where the river current speeds are moderate and many pools are present. The grayling is very sensitive to industrial pollution.
Grayling as a Sport Fish
In Scotland, grayling can be fished for throughout the year. Until quite recently, the grayling did not enjoy a high reputation as a sport fish among many anglers. Indeed, it was more often seen as a possible competitor to salmon and trout, a predator on their eggs, or a nuisance by-catch, than as a desirable sport fish in its own right. This view has changed significantly in recent years, with both an increase in the popularity of fishing for grayling, and a new emphasis on conservation through catch-and-release.
The Grayling Society
In 1977, the Grayling Society was formed by a group of Grayling fishermen. The society, which now has over 1,200 members in the UK and overseas, has been instrumental in improving the image of the grayling through education, the promotion of good practice, the publication of newsletters and a journal, and by organising meetings and outings. There is an active Scottish branch.
The grayling is listed in the European Habitats Directive as a species of Community interest whose taking in the wild and exploitation may be subject to fisheries management measures.