Voracious invader or benign feline? A review of the environmental biology of European catfish Silurus glanis in its native and introduced ranges*

Abstract

A popular species for food and sport, the European catfish (Silurus glanis) is well-studied in its native range, but little studied in its introduced range. Silurus glanis is the largestbodied freshwater fish of Europe and is historically known to take a wide range of food items including human remains. As a result of its piscivorous diet, S. glanis is assumed to be an invasive fish species presenting a risk to native species and ecosystems. To assess the potential risks of S. glanis introductions, published and 'grey' literature on the species' environmental biology (but not aquaculture) was extensively reviewed. Silurus glanis appears well adapted to, and sufficiently robust for, translocation and introduction outside its native range. A nest-guarding species, S. glanis is long-lived, rather sedentary and produces relatively fewer eggs per body mass than many fish species. It appears to establish relatively easily, although more so in warmer (i.e. Mediterranean) than in northern countries (e.g. Belgium, UK). Telemetry data suggest that dispersal is linked to flooding/spates and human translation of the species. Potential impacts in its introduced European range include disease transmission, hybridization (in Greece with native endemic Aristotle's catfish [Silurus aristotelis]), predation on native species and possibly the modification of food web structure in some regions. However, S. glanis has also been reported (France, Spain, Turkmenistan) to prey intensively on other non-native species and in its native Germany to be a poor biomanipulation tool for top-down predation of zooplanktivorous fishes. As such, S. glanis is unlikely to exert trophic pressure on native fishes except in circumstances where other human impacts are already in force. In summary, virtually all aspects of the environmental biology of introduced S. glanis require further study to determine the potential risks of its introduction to novel environments.

Move or die: change in European catfish (Silurus glanisL.) behaviour caused by oxygen deficiency

“…The European catfish (Silurus glanis L.) is a common inhabitant of rivers, old oxbows and shallow alluvial lakes in the Eurasian temperate zone. Although S. glanis is native to mainland Europe, reaching the Rhine River in the west, it has also been introduced into a number of countries in southern and western Europe, and its possible predation and competitive impact on native species is being increasingly studied and discussed (Copp et al, 2009;Bevacqua et al, 2011;Martino et al, 2011). The European catfish exhibits site fidelity and utilises a stable 'resting place' (Carol et al, 2007).…”

Introduction and spread of non-native parasites withSilurus glanisL. (Teleostei: Siluridae) in UK fisheries

“…have been recorded from much of Asia and Europe (Lim et al, 2001;Moravec, 2001;Galli et al, 2003;Copp et al, 2009). Specific records for T. vistulensis include Italy, the Czech Republic, the Slovak Republic and Poland (Siwak, 1932;Moravec, 2001;Paladini et al, 2008), although these are likely to reflect detection effort rather than the true extent of distribution.…”

“…In order to better understand the ecological risks associated with this species, research has been conducted to assess the invasiveness of this fish in the UK. Most of this work has focused on colonization potential under current and future climatic conditions (Britton et al, 2007(Britton et al, , 2010Copp et al, 2009). However, according to Copp et al (2009), virtually all aspects of the environmental biology of S. glanis require further study.…”

“…Most of this work has focused on colonization potential under current and future climatic conditions (Britton et al, 2007(Britton et al, , 2010Copp et al, 2009). However, according to Copp et al (2009), virtually all aspects of the environmental biology of S. glanis require further study. This includes disease risk, as to date little attention has been given to the parasite fauna of this fish in Britain, despite awareness that it may serve as host for a wide range of parasite species (Copp et al, 2009).…”

Holocene climate change and prehistoric settlement in the lower Danube valley

“…Spawning and feeding behaviour can be significantly affected by sudden and/or prolonged changes in water temperature. Spawning in salmonids and wels catfish (Silurus glanis) may be inhibited by sudden drops in water temperature; while catfish cease to feed at temperatures below c. 10 °C and growth is impeded (Omarov and Popova, 1985;David, 2006;Copp et al, 2009). Similarly, river icing and sudden or prolonged changes in flow conditions can impact on fish populations.…”