Factors Affecting the Shift in Predominance from Eurasian Perch (Perca fluviatilis) to Roach (Rutilus rutilus) in the Kličava Reservoir, Czechoslovakia

1977 ◽  
Vol 34 (10) ◽  
pp. 1571-1575 ◽  
Author(s):  
K. Pivnička ◽  
M. Švátora
Keyword(s):  
Growth Rate ◽  
Sex Ratio ◽  
Environmental Conditions ◽  
Perca Fluviatilis ◽  
Rutilus Rutilus ◽  
Roach Rutilus Rutilus ◽  
Eurasian Perch ◽  
Factors Affecting ◽  
Perch Perca Fluviatilis ◽  
Marked Decline

A shift in predominance from Eurasian perch (Perca fluviatilis) to roach (Rutilus rutilus) in the Kličava Reservoir in 1964, 10 yr after filling, was attributed mainly to a marked decline in the ratio of female to male perch spawners. The ratio was about 1:4 for perch and unity for roach. Fecundity of perch was about 25% that of roach which, together with the decline in spawning females, probably contributed to smaller year-classes. The decline in growth rate of perch in response to increasing abundance was greater than that for roach. Under equal environmental conditions, roach is also more productive than perch. Key words: Percidae, Perca, Rutilus, Kličava Reservoir, Czechoslovakia, shift in predominance, fecundity, sex ratio, methodology, growth–abundance relationships

Changes in Fish Mercury Concentrations in an Intensively Fished Lake

1990 ◽  
Vol 47 (10) ◽  
pp. 1888-1897 ◽  
Author(s):  
Matti Verta
Keyword(s):  
Growth Rate ◽  
Perca Fluviatilis ◽  
Anguilla Anguilla ◽  
Rutilus Rutilus ◽  
Northern Pike ◽  
Top Predator ◽  
Roach Rutilus Rutilus ◽  
Perch Perca Fluviatilis ◽  
High Mercury ◽  
Total Fish

A small polyhumic lake inhabited by northern pike (Esox lucius), burbot (Lota lota), perch (Perca fluviatilis), roach (Rutilus rutilus), and eel (Anguilla anguilla) was fished intensively during spring 1984 and 1985 to lower the high mercury levels in the top predator, northern pike. A total catch of 29.5 kg∙ha−1 (74% roach) was removed which represented about 50% of the total fish biomass. Mercury concentrations in burbot, large pike, and small roach had decreased by 1987 and 1988, but increased in young pike and some perch. Northern pike had the clearest increase in growth rate, while that of perch and roach levelled off within 3 yr at the prefishing level. Only a small increase in growth rate of burbot occurred. The yearly accumulation of mercury in northern pike remained constant, and the decrease in [Hg] was apparently due to growth dilution. The decrease in [Hg] of burbot and roach is explained by a switch to a diet with lower [Hg] or a decrease in water methylmercury concentrations. The amount of methylmercury removed from the lake by fishing was equivalent to several years of calculated mercury methylation and accumulation in the fish. Overfishing may be a feasible means of lowering methylmercury levels in this type of oligotrophic lake.

Competition, predation and environmental factors as structuring forces in freshwater fish communities: Sumari (1971) revisited

1997 ◽  
Vol 54 (1) ◽  
pp. 85-88 ◽  
Author(s):  
L Persson
Keyword(s):  
Abiotic Factors ◽  
Fish Communities ◽  
Perca Fluviatilis ◽  
Rutilus Rutilus ◽  
Apparent Competition ◽  
Roach Rutilus Rutilus ◽  
Data Set ◽  
Factors Affecting ◽  
Perch Perca Fluviatilis ◽  
Species Performance

A study by Sumari (O. Sumari. 1971. Ann. Zool. Fenn. 8: 406-421) of the fish communities in 32 Finnish lakes concluded that the main factors affecting perch (Perca fluviatilis) populations were biotic, of which the competitive interspecific effect of roach (Rutilus rutilus) was the main one analysed. A reanalysis of this data set suggests that abiotic factors such as conductivity and pH are also important in structuring fish communities. It is suggested that abiotic factors affect perch abundance mainly by their effects on other species' performance, particularly roach. The analyses of the whole data set and a subset of this data set consisting of nine lakes having perch only, or perch and piscivores only, also provided evidence that piscivores affect perch biomass. A positive relationship between piscivore biomass and roach biomass suggests that the piscivore-perch-roach interaction may have involved the presence of apparent competition between roach and perch.

Sign in / Sign up

Export Citation Format

Share Document