Circumstantial evidence of gibel carp, Carassius gibelio, reproductive competition exerted on native fish species in a mesotrophic reservoir

Abstract

Gibel carp, Carassius gibelio (Bloch), impacts on native fish species have been reported but little studied despite a long history of introductions in Europe. This species is able to reproduce gynogenetically, which involves the use of sperm from males of other species to activate egg development, so reproductive competition is a likely but virtually unstudied impact of gibel carp on native fishes. This study evaluates the impact of introduced C. gibelio on the population biology of native fishes over a 6‐year period in a mesotrophic drinking water reservoir in north‐western Turkey. A dramatic decrease in the relative density (i.e. catch per unit effort) of native species correlated significantly with an increase in C. gibelio relative density. Growth characteristics (back‐calculated ages, growth index and relative condition) and length at maturity did not differ significantly among years in C. gibelio and native fishes. Relative density, duration of spawning, reproductive effort and gonado‐somatic index of C. gibelio increased with some water quality variables [total phosphorus (TP); chlorophyll‐a (Chl‐a)] and coincided with decreasing trends for natives. However, TP and Chl‐a were not correlated with growth features in C. gibelio or natives fishes. The results suggest that the decline in the reservoir’s native cyprinid populations is likely due to a combination of degrading environmental conditions and a disparity in reproductive effort, with introduced C. gibelio invasion facilitated by gynogenetic reproduction and an observed interference with native fishes during spawning.

Population Structure and Some Growth Properties of Gibel Carp (<i>Carassius gibelio</i>) in a Mesotrophic Lake

“…It is an omnivorous fish (Kottelat and Freyhöf, 2007), reproduces gynogenetically and has extensive tolerance to different environmental conditions (Ekmekçi, 2013). The reason for the intense reproductive success of introduced C. gibelio is its capacity for gynogenetic reproduction, whereby females are able to use sperm of other cyprinid fishes and salmonids to fertilize their eggs (Penaz et al, 1979;Tarkan et al, 2012). Consequently, this species easily becomes a dominant species in stagnant and slow running waters (Tsoumani et al, 2006).…”

Untitled

“…This has been the case for the gibel carp in Turkey (Aydın et al, 2011;Tarkan et al, 2012b), and was demonstrated in a large-scale study of water bodies of the Great Lakes Region (USA), which indicated that reservoirs were more prone to invasion compared to neighboring natural lakes (Johnson et al, 2008). At the same time, propagule pressure appears to be the most reasonable explanation for the link between reservoirs and nonnative species.…”

“…Previous studies have reported that the establishment success of introduced species into reservoirs may be high not only compared to natural lakes but also to water courses (Moyle and Light, 1996;Kolar and Lodge, 2002;Han et al, 2008;Aydın et al, 2011;Tarkan et al, 2012b). This has been the case for the gibel carp in Turkey (Aydın et al, 2011;Tarkan et al, 2012b), and was demonstrated in a large-scale study of water bodies of the Great Lakes Region (USA), which indicated that reservoirs were more prone to invasion compared to neighboring natural lakes (Johnson et al, 2008).…”

“…Kubecka, 1993;Riha et al, 2009;Ferincz et al , 2012), there are examples of gibel carp abundance constantly increasing at the expense of native cyprinids remaining in comparatively lower numbers (e.g. Markovic et al, 2007;Tarkan et al, 2012b).…”

“…Despite general recognition of the likely detrimental effects of accidental non-native freshwater fish introductions in Turkey (Balık et al, 2004;Gaygusuz et al, 2007;Tarkan et al, 2012b), there is still limited knowledge about the extent of such impacts (Tarkan et al, 2012a). The aim of the present study was to assess the consequences on the native fish fauna of accidental introductions of nonnative fish species as contaminants of common carp stocking into some newly-established reservoirs of north-west Anatolia.…”