Natural predators of S. glanis include otters (Lutra lutra), cormorants and waders, and other predatory fish such as pike (Esox lucius) and zander (Sander lucioperca). In vain basses and punkies erect the sharp stings on the back. Zoologische Bijdragen, 17:48-62, Bogut, I., Has-Schön, E., Cacic, M., Milakovic, Z., Novoselic, D., Brkic, S., 2002. Fisheries Management and Ecology, 11:203-212, Hilge V, 1989. Risk identification and assessment of non-native freshwater fishes: concepts and perspectives on protocols for the UK. Archives of Polish Fisheries, 11:141-147, David JA, 2006. Generate a print friendly version containing only the sections you need. Of presumable Danubian origin, this fish has diffused in almost all European rivers and lakes, often introduced by the man, as well as in the Caspian and Lake Aral basins, colonizing also the Anatolia, the southern part of the Baltic countries, and even areas of Great Britain and of Spain. Silurus glanis aralensis, Silurus silurus: Pronunciation: See loo russ - glare neess: Etymology: From the Greek silouros which is the name of the fish. Journal of Applied Ichthyology, 18(1), 1-6. doi: 10.1046/j.1439-0426.2002.00304.x. The maximum reported length is of five metres, but the specimens presently found in Italy rarely do exceed the two, also because the bigger specimens are the oldest ones and due to its age that may reach the 80 years, clearly those present in Italy will have to grow up for some decade more before reaching record dimensions. Its greater production in Bulgaria has been suggested (Hadjinikolova et al., 2010). The tiny dorsal fin on its upper body, rounded caudal fin and strong upper body assist the swimming motion. Fish movements: the introduction pathway for topmouth gudgeon Pseudorasbora parva and other non-native fishes in the UK. However, there are reports of breeding in some lakes in southern England at present temperatures (Copp et al., 2009). Growth is an integrating variable of fish physiology and behaviour, and reduced growth can result from a variety of factors: food abundance, fish age, social hierarchy, change in water temperature, habitat and increased energy expenditures (Zaikov et al. Reproduction biology in a native European catfish S. glanis, 1758, population in Menzelet Reservoir. Penil (2004) suggests that it may expand its range by movement in man-made canal networks. Journal of Fish Biology, 71:101-114, Syväranta, J., Cucherousset, J., Kopp, D., Crivelli, A., Céréghino, R., Santoul, F., 2009. They are a demersal species, find refuge in crevices and woody root habitats, and prefer slow flowing rivers and weedy covered, vegetated lakes. Geographic Range Silurus glanis, sheatfish or wels catfish, is native to eastern Europe and Asia. The potential risk of hybridization with native species is likely to be limited to native Silurus species, such as the native congener S. aristotelis in Greece. However it still accounts for only a small percentage of European freshwater aquaculture compared with the main species, rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and common carp (Cyprinus carpio) -- total production of S. glanis was 602 tonnes in 1993, increasing to 2000 tonnes in 2002, and has since stabilised at >700 tonnes/year. “Silurus glanis is a commercial fish consumed by humans. 10 ft.). PLoS ONE, 7(12), e50840. The influence of temperature on the growth of the European catfish (Silurus glanis). This species requires temperatures of 25-28ºC for optimal growth, food assimilation and breeding (Copp et al., 2009). A dart, a cloud of dust and also this is seized with no escape. Lucrari Stiintifice - Universitatea de Stiinte Agricole si Medicina Veterinara, Seria Zootehnie, 53, 284-288. Aquaculture in the Third Millennium. Several studies have indicated that the temperature threshold for optimum growth may vary between 22 and 26ºC (Mazurkiewicz et al., 2008), or 23-30ºC (Ulikowski et al., 2003) whereas Copp et al. The wels catﬁ sh, also called sheatﬁ sh ( Silurus glanis L.) is expanding very rapidly throughout the italian peninsula, com- pared to the ﬁ rst case in Italy in 1937; in the waters of the rivers represent a real threat to native ﬁ sh populations. Pairing up of males and females commences during migration as they proceed to compete for best spawning grounds in the reach of the river and in heavily vegetated lakes. Bangkok, Thailand and Rome, Italy: Network of Aquaculture Centres in AsiaPacific and FAO, Bangkok & FAO Rome, 397-416. https://enaca.org/?id=413, Vittas S, Drosopoulou E, Kappas I, Pantzartzi CN, Scouras ZG, 2011. With the first darkness it rouses from this apathy and begins its meticolous researches. Their paired pelvic fins are each made up of one spine and 11-12 soft rays and have paired pectoral fins of one spine and 14-17 soft rays. Other examples of depressed foraging activity and growth were reported at water temperatures <15ºC as fish were unable to metabolise food at temperatures <10ºC and were sedentary to minimise energy expenditure (Boujard, 1995). Currently, wels catfish are predominantly found in the South East and Midlands areas of the UK. Fisheries Management and Ecology, 14:263-268, Britton, J. R., Davies, G. D., Brazier, M., 2010. The Import of Live Fish Act 1980 (ILFA) is a legislative framework to control importation of non-native fishes, and the Fish Invasive Screening Kit (FISK) is a scoring system to assess the range of risk of non-native fish introduction ranging from potential pest to harmless, based on the evaluation of life history traits of non-native fish species, e.g. Some angling introductions are unregulated and illegal, with S. glanis transferred to unlicensed lakes in the UK that do not meet the ILFA (Import of Live Fish Act) criteria set by the Environment Agency because of risks concerning flooding and the likelihood of entry to nearby rivers. There is one clear seasonal peak in spawning per year, between May and July. There are 18 Silurus species, of which two are native to Europe: wels catfish and Aristotle's catfish (S. aristotelis). http://www.nmfs.noaa.gov/pr/pdfs/statusreviews/sturgeon_5foreign.pdf, Naylor RL, Williams SL, Strong DR, 2001. Investigation on growth rate and food conversion ratio of wels (Silurus glanis L.) in controlled conditions. Reproduction is controlled by environmental cues, e.g. 60:21-36. http://www.fao.org/fishery/en. 4.5-5.5 ft.) but may reach lengths of up to 3 m (approx. Pond culture of fish in Romania. This species is in the lower region of the high risk score category of potential pests in ENSAR (European non-native species aquaculture risk assessment) to evaluate the risk of introduction, establishment, dispersal and impacts, although this may be variable according to context (Copp et al., 2009). It has been introduced but not established in Cyprus, Belgium and Algeria (Froese and Pauly, 2012). Fish and Fisheries, 10(3):252-282. http://www.blackwell-synergy.com/loi/faf, Copp GH, Garthwaite R, Gozlan RE, 2005. Our inland waters have very impoverished and this dearth by sure is not favouring important dimensions. According to Linhart et al. [Cefas Science Technical Report No. Évolution de son aire de répartition et prédiction de son extension ([English title not available]). Diurnal and seasonal behaviour of adult and juvenile European catfish as determined by radio-telemetry in the River Berounka, Czech Republic. 9988).Found in deep waters of dams constructed on the lower reaches of rivers (Ref. (Die westliche Verbreitungsgrenze des Welses, Silurus glanis, an Rhine und Elbe.) The flattened snout with spaced apart nostrils and long barbels on either side of the upper jaw, and 4 shorter barbels on the lower jaw, indicate that S. glanis sense their prey by highly sensitive chemical and olfactory sensors on their barbels and nostrils rather than by vision, as their eyes are small; this can be related to their benthic habitat ecology (Copp et al., 2009). 2008; Muscalu et al. Fast growth is advantageous for non-natives in minimising predation by quickly exceeding gape size of native predators, and in increasing foraging opportunities (Hendry et al. 2007; Carol et al. Reviews in Fish Biology and Fisheries, 21(2), 283-294. http://www.springerlink.com/link.asp?id=100215 doi: 10.1007/s11160-010-9168-4, Bevacqua D, Andrello M, Melià P, Vincenzi S, Leo GA de, Crivelli AJ, 2011. SiluroMania si occupa inoltre della salvaguardia del silurus glanis, diventato un vero e proprio capro espiatorio per i crimini compiuti dall'uomo nell'ambiente. Incubation lasts about 50 hours at 24°C. Acta Ichthyologica et Piscatoria, 26(1), 93-101. – Contenimento della presenza di Silurus glanis nelle acque dell’Adda ricomprese nel territorio del Parco Adda Nord e, nel comtempo, contenimento di altre specie ittiche alloctone dannose per l’equilibrio delle specie autoctone (come il gardon, il rodeo amaro, il carassio). 2002; Ulikowski et al. Establishment success in France has been restricted by cold winter temperatures of <10ºC (David, 2006). pond cultivation. Detailed coverage of invasive species threatening livelihoods and the environment worldwide. Sperm cryopreservation of two European predator fish species, the Pikeperch (Sander lucioperca) and the Wels Catfish (Silurus glanis). [ISBN 90-71625-03-6], Hilge, V, 1984. Silurus glanis, conosciuto volgarmente come siluro o siluro d'Europa o anche pesce siluro, è un pesce d'acqua dolce europeo, appartenente alla famiglia dei Siluridae e all'ordine Siluriformes. Science (Washington), 290(5491), 516-518. doi: 10.1126/science.290.5491.516, Hickley P, Chare S, 2004. > 0°C, dry summers, Cw - Warm temperate climate with dry winter, Warm temperate climate with dry winter (Warm average temp. 02015 1144 Geräucherte Spezialitäten aus Schlesien.JPG 2,159 × 2,989; 2.28 MB 2009). Are fish introductions a threat to endemic freshwater fishes in the northern Mediterranean region? 2012). To protect species or infer their invasiveness potential, it is necessary to understand the origin, genetic diversity and migration patterns. Wels catfish exhibit parental care of young, and the males guard clusters of eggs adhered to woody tree roots and submerged macrophytes in riparian reaches and floodplains (Copp et al., 2009). Proliferation has been assisted by unregulated introductions in many countries (Hickley and Chare, 2004; Clavero and Garcia-Berthou, 2006). Bulgarian Journal of Agricultural Science, 16(3), 398-405. http://agrojournal.org, Hamackova J, Szlaminska M, Kouril M, Vachta J, Stibranyiova I, 1997. Harka, A, 1984. Silurus glanis - Wikipedi . In an initial invasiveness assessment, Copp et al. Fondi per il contenimento del pesce siluro sul territorio cremasco Si interverrà nei comuni di Crema, Madignano, Ripalta Cremasca, Ripalta Arpina, Ripalta Guerina e Montodine dove è stata accertata la presenza del pesce siluro. Zaykov, A., Hubenova-Siderova, T., 1998. Czech Journal of Animal Science, 44(1), 29-37. Pesci siluro nel Garda, l’allarme dei pescatori . Sexual maturity is generally 3-4 yrs, between 39-71 cm length. The culture of the European catfish S. glanis in the Czech Republic and in France. Fish consumption is low in central and eastern European countries in comparison to western Europe, which may be related to economic factors including income, fisheries trading and distribution (fish is more expensive than meat in most eastern European countries). Journal of Fish Biology, 63:131-143. However, Martino et al. Grozev, D., Hubenova-Siderova, T., Zaikov, A., 2000. Species. 06023 Maq OK.indd 19 21/07/2008 13:52:23 Manual de restauración de humedales mediterráneos 3.2 Directiva marco del agua y restauración del estado ecológico de los humedales Nel suo areale originario la specie presenta numerosi problemi di conservazione, specialmente legati al suo limite di diffusione, per via The colour is dark grey on the back and goes down on the sides with a moire where clear and dark colours mix irregularly, to end in an opaque white belly. The catfishes spend the day in impenetrable hideouts and get out hunting by night; amphibians and young fishes but then also small mammals and aquatic birds © G. Mazza. For positive economic effects, see the sections on Uses (Invasive Species Compendium) or Production, Economic and Socioeconomic Aspects (Aquaculture Compendium). Two small eyes, with circular pupil, stand out laterally just over the oral margins. The other “accessories” are proportionally tiny: two pectoral fins little worth of the size of the fish, two small pelvic fins and a sort dorsal, at times erect to serve as pivot for a turn. Amazing video: Yuri Grisendi that fight a monster #catfish over 260. When the water exceeds the 20 °C, the males dig small basins that will cover with weeds and twigs where the spawning will take place. This albino young seems to smile affable. 1996; Ulikowski et al. Proceedings of the National Academy of Sciences of Belarus., Agrarian Science Series: 2:75-86. Fontenay-sous-Bois, France: Conseil Supérieur de la Pêche, 92 pp, Varadi, L., Szucs, I., Pekar, F., Blokhin, S., Csavas, I., 2001. 2001) with some limited but renewed awareness among fish farmers in France and Germany (Linhart et al. In parts of its native range (e.g. River Hampshire Avon assessment of risk posed by S. glanis. Effect of stocking density and three various diets on growth and survival of European catfish (Silurus glanis L.) larvae under intensive rearing condition. Gli impatti economici sono più probabili nei laghi prealpini (ove si esercita maggiormente la pesca di professione), mentre gli ... www.naturachevale.it . 2000). 59043).Occurs mainly in large lakes and rivers, though occasionally enters brackish water in the Baltic and Black Seas (Ref. Journal of Ichthyology, 18:457-468, Simoens I, Breine JJ, Verreycken H, Belpaire C, 2002. ©Dieter Florian/via wikipedia - CC BY-SA 3.0 DE. The European catfish (Silurus glanis) can reach the 80 years with record size of 5 m and 300 kg. The database includes records of species introduced or transferred from one country to another. S. glanis cultivation has played a minor role in cyprinid pond farming. [English title not available]. Concerns about accidental unregulated spread (flooding enabling spread from angling waters to watercourses and rivers) and intentional unregulated releases (for angling) imply that S. glanis introductions need to be investigated, particularly as angling and dispersal are cited as the main introduction routes for introduced fish in the UK ( Copp et al. Silurus glanis (wels catfish); line caught adult. > 10°C, Cold average temp. Copepoda are the most frequent food of smaller larvae. It appears to establish relatively easily after introduction, especially in warmer climates such as around the Mediterranean (Crivelli, 1995). Il Siluro (Silurus glanis), originario dell’Europa centro settentrionale e dell’Asia Minore, … CABI is a registered EU trademark. National Marine Fisheries Service,
Reproductive success in male sunbleak, a recent invasive fish species in the UK. 2011; Martino et al. A “do nothing” approach is advocated in low risk situations, whereas removal or containment are considered options in higher risk situations. Aquatic Invasions, 2:113-116, Copp GH, Vilizzi L, Gozlan RE, 2010. The other factor limitating its growth is the quantity of food. Fundamental and Applied Limnology, 174:317-328, Carol J, Garcia-Berthou E, 2007. ... silurus glanis. It and Sander lucioperca are predatory fish that are traditionally reared to control wild forage fish dispersed during seasonal pond flooding that may be interspecific competitors with cyprinids (Bokor et al. 1998; Zaykov and Hubenova-Siderova, 1998; Prokés et al., 1999; Grozev et al., 2000; Bogut et al., 2002; Paschos et al., 2004; Kim et al., 2005; Dediu et al., 2010; Alp et al., 2011; Jamróz et al., 2008; Muscalu et al., 2010), and on food conversion of cultured S. glanis (particularly using meal pellets), e.g. It has been introduced to several other areas including Germany, France, Spain, England, Greece, Turkey and the Netherlands. The prey that ends up between its lips has no escape. Their eyes are small and they rely on their barbels and olfactory cavities to sense their prey and environment rather than vision. During the night it roams wandering and diving the big head on the preys that the long barbels, always busy, have revealed. Is European catfish a threat to eels in southern France? Molecular Ecology, 11:1039-1055. Rome, Italy: Food and Agriculture Organization of the United Nations. © MONACO NATURE ENCYCLOPEDIA | All rights reserved. Development of technological regimes of European catfish (Silurus glanis L.) growing in the ponds of Belarus. 2011; Syväranta et al. Another reason for introductions is as a biocontrol agent for controlling cyprinid fish. Towards the successful control of the invasive Pseudorasbora parva in the UK. Body colour is variable but normally dark greenish-black with creamy yellow sides creating a mottled effect.They are solitary, predatory, opportunistic scavengers that hunt for stragglers (Boujard, 1995; Copp et al., 2009; Britton et al., 2010). Krmiva, 37(3), 129-134. In other locations, instead, it is forbidden to the fishermen taking it ashore to place it again in water. Studies on wels catfish (Silurus glanis) development during cold season as an auxiliary species in sturgeon recirculated aquaculture systems. In April 2012, accidental flooding from licensed lakes containing wels catfish into flood valleys of the River Colne and Chelmer in East Anglia were being investigated. Consequently, most fish production is exported to other countries; for example the majority of O. mykiss production in Poland is exported to Germany (FAO, 2012; Varadi et al. S. glanis has fewer alleles than S. aristotelis and S. triostegus but similar observed and expected heterozygosities (Krieg et al., 1999). Being a great eater that consumes every day almost the 2% of its own body weight, and finding in the new habitats where has been introduced quite a few natural foes (only the big pikes and zanders), it’s revealing to be a real pest, to the point that in some zones the underwater fishing is allowed even with the aqualung. Following spawning, S. glanis exhibits a guarders and nesters reproductive strategy with the male protecting the cluster of eggs laid by the female in his nest excavated amongst the substratum and made from plant material. The European catfish or Wels catfish (Silurus glanis Linnaeus 1758) is a freshwater fish belonging to the class of the Actinopterygii, ray-finned fishes, to the order of the Siluriformes, and to the family of the Siluridae, that has no rigid rays in the dorsal, has no adipose fin and has some small ventral fins (at times missing) and a very long anal fin. → For general information about fishes please click here. The anal fin, very long, renders the body similar to a waving blade between the 6 stretched barbels © Giuseppe Mazza. Native to eastern Europe and western Asia it is now established in several countries to the west and south of its native range. ], Copp GH, Moffatt L, Wesley KJ, 2007. SILURUS GLANIS ASSOCIATION has 2,760 members. 2008). Movement to new areas is generally through introduction for aquaculture and recreational fishing, or sometimes for biological control. Risk of establishment increases in warmer climates such as the Mediterranean as rapid growth and breeding are enhanced by warmer temperatures of 25-28ºC in contrast to likelihood of more sporadic establishment in Northern climates. Comparison of morphology, growth and survival between Silurus glanis, S. aristotelis and their hybrid during larval and juvenile stages. Wels catfish can be distinguished from other European catfish by the 6 long barbels under the lower jaw, the scaleless mucous-coated elongated body and the very small dorsal fin (Britton et al., 2010). The skin can be used in glue and leather manufacture. There is intensive daytime use of littoral habitat, resting within dense vegetation (Copp et al., 2009). Control management options for S. glanis vary according to assessment of severity of risk. Journal of Animal and Veterinary Advances, 7(10), 1285-1291. http://www.medwelljournals.com/fulltext/java/2008/1285-1291.pdf, Hadjinikolova, L., Hubenova, T., Zaikov, A., 2010. Deliberate introductions have also been followed by accidental escape and dispersal to other waters, as has been reported by Boeseman (1975) in the Netherlands, where it was introduced from Hungary. (2002) report that in Lake Schulen in Flanders (Belgium), large wels catfish which had been illegally introduced by anglers had successfully reproduced. The newborns will remain in the nest till when they have not competely absorbes the yolk sac and will reach the sexual maturity in 2-3 years. Routes of introduction of S. glanis include recreational angling, aquaculture and also use as a biological control agent for cyprinid fish, with certain pathways being more frequent in some countries; for example, the species is predominantly farmed in aquaculture in Italy, Romania, Poland and the Netherlands, but used mainly to enhance recreational angling in the UK. Toward a global information system for invasive species. Males mature earlier than females, with mass maturation at 3-4 yrs, 57-66 cm and 1.3-2.3 kg, in contrast to females that mature at 4 yrs at minimum length 87.05 cm (Alp et al., 2004; Froese and Pauly, 2012). PLoS ONE, 6(10), e25732. Bokor, Z., Urbányi, B., Horváth, L., Müller, T., Horváth, A., 2012. The introduction of S. glanis in angling clubs is likely to increase revenue to local communities and generate business. The sheer size of this fish has also attracted scuba-divers to some lakes where it has been introduced in the Netherlands (and probably elsewhere), which also generates local revenue. This can vary from two to ten days from the deposition, depending on the water temperature. Zivocisna Vyroba, 42:27-32. What stands out most are the formidable barbels, about twice long than the head, that protrude laterally in front of the eyes. Aquacultura Hungarica, 4: 135-144. Slimy monster without scales with 2 measureless barbels near the eyes and others on the chin completing the range of the sensors © Giuseppe Mazza. They have a tiny dorsal fin made up of a single spine and 4-5 dorsal soft rays, one anal spine, 83-95 soft anal rays and a caudal fin of 17 soft rays (Froese and Pauly, 2012). Life span is normally 15-30 years, with a maximum recorded age of 80 years (Kottelat and Freyhof, 2007). The revealed that levels of genetic diversity were much higher than previous allozyme and restriction fragment length polymorphism mitochondrial DNA analyses had shown. (Black, Predator-fishing.co.uk 2005) Cornol, Switzerland: Publications Kottelat, 646 pp, Krieg F, Estoup A, Triantafyllidis A, Guyomard R, 1999. Investigating the catch returns and growth rate of Wels catfish (Siluris glanis), using mark-recapture. Consumption of food sources is related to gape size with the larger catfish >120 cm in length consuming aquatic wildfowl and mammals in comparison to smaller counterparts of <30 cm feeding on invertebrates and molluscs. 2009; Copp et al. Species and size selectivity of European cat-fish (Silurus glanis) to natural food when reared in aquarium to one month of age. Territorio. GardaPost Gen 11, 2020. Colossal aggregations of giant alien freshwater fish as a potential biogeochemical hotspot. There are reports of escapes from aquaculture and recreational fisheries, for example in France where it escaped into the River Doubs in about 1890 (Valadou, 2007). According to Linhart et al. 55 relazioni. Firstly they may increase competition for habitats of native fish, including the critically endangered eel (Anguilla anguilla). The profile of the fish might recall a Neolithic knife with a massive handle and long blade (specifying that in that time the blades were short). by Cowx, I. G.]. FishBase. Simoens et al. Archiwum Rybactwa Polskiego, 6(1), 97-106. The species is an effective ambush predator of slower moving Cyprinid species (Copp et al., 2009). Siluris glanis Linnaeus, 1758; Silurus silurus Wulff, 1765; Silurus glanis aralensis Kessler, 1872. In the origin countries, besides the flesh consumed fresh or smoked, the skin is utilized for producing glues and for the leather industry. In Italy it has been introduced since about fifty years and now has colonized almost all the waters of the Po River basin and the rivers Arno and Tiber. 2008). When several references are cited, they may give conflicting information on the status. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0050840 doi: 10.1371/journal.pone.0050840, Czarnecki, M., Andrzejewski, W., Mastynski, J., 2012. The addition of wels catfish in recreational catch and release fisheries is likely to have a beneficial revenue effect. Evaluation of production efficiency of selected feed mixes of intensive culture of European wels (Silurus glanis L.). Zaikov, A., Iliev, I., Hubenova, T., 2008. Besides the usual diet of fishes and amphibians, the biggest specimens seize also small mammals and waterfowls. Consumer popularity of cultured S. glanis has remained low (Varadi et al. Acta Ichthyologica et Piscatoria, 27(1), 41-50. Migration to European rivers including the Danube, Dnieper and Volga was via the Caspian, Black and Aral seas. Wels catfish are also hosts of specialist parasites such as Trichodina siluri, Myxobolus miyarii, Leptorhynchoides plagicephalus and Pseudotracheliastes stellifer which may be detrimental to native fish survival (Copp et al. [Unpublished report], Ricciardi A, Steiner WWM, Mack RN, Simberloff D, 2000. In contrast, O. mykiss total production was 300,000 tonnes in 2005, and the figure had risen to 700,000 tonnes in 2010 and was likely to increase (FAO, 2012; Linhart et al. 2010). Removal of wels catfish from unlicensed lakes appears to be a priority for the Environment Agency in England and Wales, although how successful these measures are in practice has yet to be ascertained. Average temp. Status Review Report of 5 Species of Foreign Sturgeon. The male guards the eggs for the next 2-10 days (time dependent on water temperature) and makes sure the eggs are well ventilated by repeatedly fanning his tail fin, until they hatch out (Copp et al., 2009). Aquatic Conservation: Marine and Freshwater Ecosystems, 21(3):276-281. http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-0755, Mazurkiewicz, J., Przybyl, A., Golski, J., 2008. The species sometimes enters brackish water in the Black Sea and Baltic Sea (Froese and Pauly, 2012). Mouth is large and broad with very small, pointed teeth. Non-native fishes and climate change: predicting species responses to warming temperatures in a temperate region. Results of rearing two-year-old European wels (Silurus glanis L.) in ponds stocked with intensively cultured yearling.