Perch

Order: Perciformes Suborder: Percoidei Family: Percidae

Foto. Ari Saura

Description: Typical characteristics of the perch are the dark vertical stripes on its sides, the orange-red pelvic, anal and caudal fins, and the dark spot at the posterior edge of the first dorsal fin. The scales are rough and tightly attached to the skin. Regrettably familiar to anglers are the spines on the operculum and anterior dorsal fin. In Finland, two close relatives of perch are the zander or pikeperch (Sander lucioperca) and the ruffe (Gymnocephalus cernuus).

Origin and distribution: The perch occurs widely throughout Europe except in Spain, Portugal, southern Italy, the western Balkan Peninsula, and islands of the North Atlantic. In Finland, it is common and abundant almost countrywide, a sign of its adaptability. It has better tolerance to acidic water than other native fish species and it is also common in coastal waters of the Baltic Sea.

Reproduction: Perch reach sexual maturity at an age of 2−5 years and a length of 9 to 14 cm. The female has only a single ovary but the male has the usual two gonads. In southern Finland, the spawning season begins in late April or early May and lasts until June or, in cool northern waters, even until July. During spawning, the female sheds a light-coloured spiral chain of eggs onto debris or aquatic vegetation. Embryogenesis starts with immediate fertilization by the milt of several males. After 10 to 15 days, 5−6-mm-long larvae hatch from the translucent string of eggs. The larvae first disperse into the pelagial, and then gradually return to the littoral for feeding.

Diet, growth and migrations: The growth rate of perch depends on feeding conditions and population density. The diet is very diverse, comprising zooplankton, benthos and fish. A shift to predatory feeding is a prerequisite for good growth. The mean length of perch in small lakes in forested areas is often no more than 15−16 cm and weight 30−50 g. In favourable circumstances, however, perch may reach a length of 40 cm and a weight of 1 kg within 10 years. The maximum weight can be in excess of 3 kg. In brackish waters, perch migrate in shoals between feeding areas and spawning grounds, usually over a distance of a few kilometres but sometimes for more than 100 km.

Fishing and catches: Being abundant and easy to catch, perch (along with roach) tend to be the first catch of the young angler. In Finland, the annual perch catch by recreational fishermen has been about 11 to 18 million kg, which is almost one-third of their total catch. In sea areas, about 35 per cent of the total perch catch has been taken by commercial fishermen in recent years.

Vulnerability, threats and management: The perch is a least concern species in Finland, with abundant populations inhabiting fresh waters. Strong stocks also live in the Archipelago Sea and the Bothnian Sea. Recently, catches have declined somewhat in the Gulf of Finland. Some stocks have been adversely affected by intense eutrophication and acidification.

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