Silurus glanis has the potential for high environmental impact if introduced to the Great Lakes. In early stage invasion sites, S. glanis mainly consumed fish because of a high abundance of small cyprinid species, such as Roach and Bleak (Carol et al. 2007). In contrast, crayfish was the main prey of catfish in advanced stage invasion sites and the ontogenetic shift to piscivory was delayed until the catfish grew larger. Accordingly, these advanced stage invasion reservoirs had size structures dominated by larger sizes of Common Carp. Although further data are needed to see how frequent these patterns are, the results strongly suggest that at the early stages of invasion, catfish grow faster and are in better condition because they prey more on fish. As invasion proceeds, however, the catfish reduce fish numbers, particularly of smaller fish, indirectly favoring crayfish and eventually resulting in their own reduced growth rates (Carol 2009).
In addition to fish prey, another likely ecological impact of catfish is on some groups of waterbirds, especially in the Anatidae family. A few birds have been observed in the catfish stomachs, (Omarov and Popova 1984, Czarnecki et al. 2003). Carol et al. (2009) also found that waterbird abundance varied significantly with the invasion sequence (advance stage correlated with lower bird abundance) and this did not appear to be correlated or confounded by abiotic factors (such as reservoir size, altitude or trophic state). The significantly lower abundance of waterbirds in reservoirs with catfish could be due to either a direct ecological impact (predation) by catfish and/or to avoidance behavior by waterbirds to reduce predation risk (Carol 2009).
Silurus glanis takes advantage of its diet plasticity and ability to prey upon the most abundant available species of a suitable size within its habitat (Carol 2009; Syväranta et al. 2010; Martino et al. 2011). If established as an apex predator in an ecosystem, S. glanis can heavily impact other species through predation and food web alterations (Vejrik et al. 2017a). Silurus glanis has even been reported to consume Atlantic salmon (Salmo salar) in France (Boulêtreau et al. 2017). In French rivers, an invasion of S. glanis impacted some fish communities, but not on a generalised basis as some rivers were productive enough to support both invasive species and natives (Guillerault et al. 2015). Silurus glanis may adapt foraging behaviors in new habitats and introduced populations have been observed to breach onto land to capture birds (Syväranta 2010; Cucherousset et al. 2012).
Silurus glanis has a growing list of associated parasites (Copp et al. 2009): Parasites in the family Myxobolidae, are known to infect S. glanis and can have a significant pathological impact on wild and cultured fishes. Such episodes of infection are often preceded by environmental stressors such as oxygen depletion (Lom and Dykova 1992). Acanthocephalans (L. plagicephalus), another common parasite of S. glanis, can cause extensive damage such as lesions to the intestinal tract of fish where they attach leading secondarily to infections by bacteria (Dezfuli et al. 1990). High intensities of parasitic crustaceans such as Ergasilus sieboldi can inflict severe damage to the gills (Dezfuli et al. 2003) resulting in large scale mortalities of fish (Kabata 1979). Silurus glanis is also subject to Aeromonas veronii infection, which is known to cause economic losses in aquaculture (Xiucai et al. 2019). The parasitic nematode Anisaki schupakovbia infects S. glanis, which when consumed by humans can cause anisakiasis (Abdybekova et al. 2020). Other known parasites include Triaenophorus crassus, Raphidascaroides sp., Lernaea cyprinacea (Khara et al. 2016), Lamproglena pulchella (Molnar et al. 2018), Sphaerospora siluri (Patra et al. 2018), Thaparocleidus vistulensi (Rees 2020), and mycoplasmas (Sellyei et al. 2020). Silurus glanis can carry the European sheatfish virus (ESV), a strain of ranavirus, which has been reported to also infect and be lethal to Zebrafish (Danio rerio), Pike (Esox lucius), and Pike-perch (Sander lucioperca) (Jensen et al. 2009, 2011; Martin et al. 2015).
Accumulation of heavy metals and chemicals such as PCBs and PAHs in S. glanis has been recorded above acceptable levels for human consumption and may be damaging to ecosystem health (Ivanovic et al. 2016; Milanov et al. 2016; Pastorino et al. 2016; Squadrone et al. 2016).
There is little or no evidence to support that Silurus glanis has the potential for significant socio-economic impacts if introduced to the Great Lakes.
Accumulation of heavy metals and chemicals such as PCBs and PAHs in S. glanis has been recorded above acceptable levels for human consumption and may be damaging to ecosystem health (Ivanovic et al. 2016; Milanov et al. 2016; Pastorino et al. 2016; Squadrone et al. 2016).
The parasitic nematode Anisaki schupakovbia infects S. glanis, which when consumed by humans can cause anisakiasis (Abdybekova et al. 2020).
Silurus glanis has the potential for high beneficial impact if introduced to the Great Lakes.
Silurus glanis has an economic importance in commercial and recreational fisheries as well as in aquaculture. Its aquaculture production has increased from 600 tonnes in 1993 to 2,000 tonnes in 2002 in ten European countries (Linhart et al. 2002; Copp et al. 2009). Fast and efficient growth, ease of breeding and rearing, and recent genome manipulation makes S. glanis ideal for commercial aquaculture (Copp et al. 2009; Cucherousset et al. 2018). Silurus glanis is considered a delicacy in some countries (Hungary, Poland, Slovakia, Lithuania), where it is exploited for its flesh (tender white meat), skin (for leather and glue production), and eggs (for caviar) (Copp et al. 2009). The flesh of S. glanis is highly nutritious in regard to fatty acid composition (Saliu et al. 2017; Linhartova et al. 2018) and protein quality (Pyz-Lukasik and Paszkiewicz 2018).The popularity of S. glanis relates to the large sizes they can reach; they are perceived as an attractive big-game species by many United Kingdom anglers (Hickley and Chare 2004). They are also a prized pet species, with specimens in the United States advertised for thousands of dollars.
The broad diet of S. glanis extends to species considered invasive to the Great Lakes, including Sea Lamprey (Petromyzon marinus) (Boulêtreau et al. 2020), Rudd (Scardinius erythrophthalmus), Tubenose (Proterorhinus semilunaris), Round (Neogobius melanostomus) and Monkey Goby (Neogobius fluviatilis), and Zebra mussels (Dreissena polymorpha) (Didenko et al. 2016; Mikl et al. 2017). They also consume European Perch (Perca fluviatilis) eggs, which were originally thought to be unpalatable to fish (Vejrik et al. 2017b).
Silurus glanis has value as a research and medicinal subject. Its environmental resilience and longevity make it useful for modeling the effects of parasites (Defzuli et al. 2017) and contamination of hexachlorobenzene and hexachlorobutadiene (Dosis et al. 2017). Further, S. glanis is an important model for investigating evolutionary dynamics of fish chromosomes (Ditcharoen et al. 2019).