Roach

(Rutilus rutilus)

Order: Cypriniformes Family: Cyprinidae

Foto: Ari Saura

Description: Red eyes have been considered the most distinctive characteristic of the roach, though this is not necessarily so in eutrophicated waters or the sea. The fins may have a red tint, and the mouth is small and terminal. The dorsal fin origin is above the pelvic fin origin, which distinguishes the roach from the red-finned rudd (Scardinius erythrophthalmus), whose dorsal fin origin is well behind the pelvic fin origin. The number of scales on the lateral line of the roach ranges from 42 to 45 and there are 12-14 rays in the anal fin.

Distribution: The roach occurs throughout almost all Europe, with the exception of the North Atlantic islands, areas south of the Alps and the Pyrenees, and the northern mountainous area. In the east its distribution extends to the eastern side of the Urals and to the Aral Sea catchment. The original range has been extended through releases. Dedicated roach angler emigrants have introduced the species to new waters in Britain, Australia and Madagascar. In Finland, too, some releases were carried out in the 19th century. With the exception of northernmost Lapland, the roach occurs everywhere in Finland, and is indeed one of the most common species in this country. It is at its most abundant in eutrophicated lakes and ponds. As a result of eutrophication, it has increased in the Gulf of Finland and Archipelago Sea, and more recently also in the outer archipelago. The success of the species is due to its efficient reproduction and dispersion, and to its ability to use a wide variety of food items and spawning grounds.

Reproduction: Roach usually reach maturity at an 3−5 years of age. Spawning begins in spring when the water temperature has reached 10 °C. Roach spawn in groups in shallow coastal waters, usually among the vegetation in fresh water or in marine areas influenced by fresh water. They can also run upstream to spawn in brooks or rivers.

Diet, growth and migrations: As well as plankton crustaceans, roach feed on bottom fauna and sometimes even plant food. They also feed on gastropods and blue mussels (Mytilus edulis). The growth rate varies significantly both between individuals and between water systems. In one lake alone, the age of a 20-cm-long roach may be anything from 5 to 10 years. The growth rate depends on the amount of food available and the stock density. The roach tends to be a rather local species. Fish mostly overwinter in deeper waters and migrate to shallow breeding grounds in spring. After spawning, they may be found at all water depths. In Lake Vesijärvi, roach have been observed to migrate in early summer to open water, where they can prey on zooplankton. Roach compete for food with other cyprinids and perch (Perca fluviatilis), whereas they, in turn, are an important prey species for perch and pike (Esox lucius).

Fishing and catches: In earlier times, the roach was a common food fish, and was preserved by drying and salting. Catch statistics show that 5 million kg were caught in 2002, mainly in inland waters. The great majority are taken as bycatch. Roach and other cyprinids have been held partly to blame for the mass occurrence of cyanobacteria in eutrophicated waters, since nutrients are released when they feed on the bottom. Thus, in many lakes mass removal of roach and bream has taken place as a management action to improve the quality of the water.

Vulnerability, threats and management: The roach is well able to feed in turbid waters. Being sensitive to acidification, it is absent from many acidic ponds where the perch still occurs.

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