Grayling

Graylings
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Salmoniformes Family: Salmonidae Subfamily: Thymallinae Genus: Thymallus
Species
Thymallus arcticus arcticus Thymallus arcticus baicalensis Thymallus arcticus grubii Thymallus arcticus pallasi Thymallus brevirostris Thymallus nigrescens Thymallus thymallus Thymallus yaluensis

For other uses, see Grayling (disambiguation).

Graylings are moderate-sized freshwater fish, salmonidss of the subfamily Thymallinae, genus Thymallus. There are five distinct species recognized; their range includes the cold Arctic waters of northern and central Canada, Alaska and the Missouri River and Mississippi River basins in the United States, northern Europe including the UK (but introduced to Scotland), and northern Asia including Siberia, Korea and northwestern Mongolia.

Due to their agreeable taste and attractive form, graylings are valued as a food and game fish; they are occasionally seen in public aquaria. The most economically important species, for which fisheries and aquaculture operations exist, are the Arctic Grayling (Thymallus arcticus) and Grayling (Thymallus thymallus). The former species is further divided into five subspecies, with all but T. artcticus arcticus having limited ranges.

Table of contents

1 Description 2 Habitat and diet 3 Behaviour and reproduction 4 Species 5 See also

Description

Graylings are distinguished from other members of the salmon family by their larger scales, their small mouths with teeth on the maxillary bone, and most striking of all, their showy, sail-like dorsal fins. This fin is longer in males and highly colourful, with spots of red, orange, purple or green. The body is also colourful; the dorsal surface is a dark purplish to bluish black or gray, grading to dark blue or silver gray on the flanks and gray or white on the belly.

The body is further decorated with a smattering of small dark spots; these are much more numerous in juveniles. In T. arcticus there is a dark longitudinal line between the pectoral and pelvic fins. The flanks may possess a pink iridescence.

The largest species in terms of length is the Arctic Grayling (T. arcticus arcticus) at a maximum 76 centimetres (2.5 feet) in length and 3.83 kilograms (8.4 pounds) in weight; other subspecies of T. arcticus are typically half the length or less. Thymallus thymallus, while somewhat shorter (60 centimetres) may weigh significantly more (6.7 kilograms or 14 pounds).

Habitat and diet

's bait.]] As they are highly sensitive to changes in water quality, graylings may be considered indicator species; T. arcticus arcticus has largely disappeared from the Great Lakes basin. Graylings require cool, well-oxygenated water, preferrably with a swift current. The fish are found in large sandy- or gravelly-bottomed rivers and lakes, but T. thymallus may occasionally be found in brackish conditions.

Insects and zooplankton form the bulk of the grayling diet, but larger specimens may also take smaller fish and fish eggs, molluscs and even small mammals such as lemmings.

Behaviour and reproduction

Graylings keep to the surface and midwater, intercepting any edibles which happen to drift by overhead. The fish are peaceful outside the spawning season, and may form small schools.

Spawning takes place in the spring, when graylings seek the shallow areas of rivers with fine sand substrate and moderate current. The males then establish individual territories and court the females by flashing their colourful dorsal fins; the fins are also used to brace receptive females during the vibratory release of milt and roe.

As non-guarders, the eggs are left to mix with the substrate. Although the fish do not excavate nests, the highly energetic courtship and mating tends to kick up silt and cover the eggs. The eggs are small (c. 3 millimetres in diameter) and hatch after 2-3 weeks. The hatched larvae remain in the substrate until they reach a length of c. 12-18 millimetres, at which time they form shoals at the river margins. The fry grow quickly during their first year or two of life. Graylings may live for 18 years or more.

Species

• Thymallus arcticus arcticus - Arctic Grayling
• Thymallus arcticus baicalensis - Baikal Black Grayling
• Thymallus arcticus grubii - Amur Grayling
• Thymallus arcticus pallasi - East Siberian Grayling
• Thymallus brevirostris - Mongolian Grayling
• Thymallus nigrescens - Kosogol Grayling
• Thymallus thymallus - Grayling
• Thymallus yaluensis

See also

• List of fish common names
• List of fish families