A Review of Pikeperch (Stizostedion lucioperca), Eurasian Perch (Perca fluviatilis), and Ruff (Gymnocephalus cernua) in Finland

Abstract

Three percids occur in Finland: the Eurasian perch (Perca fluviatilis), the pikeperch (Stizostedion lucioperca), and the ruff (Gymnocephalus cernua). Perch occur throughout Finland, whereas ruff and pikeperch show a more southerly distribution. The pikeperch prefers lakes of medium or large area and the perch small lakes. A negative correlation was found between the size of the population of the perch and the number of fish species present. The growth rate for all species is higher in brackish water than in freshwater, and also has been higher in recent than earlier years.The correlation between the intensity of color of the water and the percentage of predaceous fish in catches, perch and pikeperch included, is negative. Perch lived longer in ponds with dark water than in those with clear and eutrophic waters. Ruff and small perch are typically prey species, while the pikeperch is a major predator.The environmental toxins cadmium, lead, DDT, and PCBs were found in only slight concentrations in percids. Highest concentrations of mercury were found in fish taken from waters near the main sites of the cellulose industry. Concentrations in the percids have decreased since 1968 due to the reduction in mercury output.Catches of pikeperch from freshwater showed a decrease and those from brackish water an increase during 1953–73. Perch catches have increased. Key words: Percidae, Finnish percids, Stizostedion, Perca, Gymnocephalus, life history, environmental toxins, heavy metals, distribution, water color, yield