Wels catfish
Wels catfish | |
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Near Leipzig, Germany | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Siluriformes |
Family: | Siluridae |
Genus: | Silurus |
Species: | S. glanis
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Binomial name | |
Silurus glanis | |
Range of the wels catfish. Red: native occurrence. Blue: occurrence in coastal waters. Orange: (re)introduced |
The wels catfish (
Etymology
The English common name comes from
Description
The wels catfish's mouth contains lines of numerous small teeth, two long
The female produces up to 30,000
The wels catfish is a long-lived species, with a specimen of 70 years old having been captured during a recent study in Sweden.[3]
Size
With a total length possibly exceeding 3 m (9.8 ft) and a maximum weight of over 200 kg (440 lb),
Most adult wels catfish are about 1.3–1.6 m (4 ft 3 in – 5 ft 3 in) long; fish longer than 2 m (6 ft 7 in) are a rarity. At 1.5 m (4 ft 11 in) they can weigh 15–20 kg (33–44 lb) and at 2.2 m (7 ft 3 in) they can weigh 65 kg (143 lb).
Only under exceptionally good living circumstances can the wels catfish reach lengths of more than 2 m (6 ft 7 in), as with the record wels catfish of Kiebingen (near
The heaviest authenticated specimen, captured from the river Po by a Hungarian fisherman in 2010,[11] weighed 134.97 kg (297.6 lb), although there are recent anecdotal reports of larger wels exceeding 140 kg (300 lb).[12][13][14] Meanwhile, the longest wels on record was an unweighed specimen from the Po measuring 2.85 m (9.4 ft), captured in 2023 [15].
Exceptionally large specimens are rumored to attack humans in rare instances, a claim investigated by extreme angler Jeremy Wade in an episode of the Animal Planet television series River Monsters following his capture of three fish, two of about 66 kg (145 lb) and one of 74 kg (164 lb), of which two attempted to attack him following their release. A report in the Austrian newspaper Der Standard on 5 August 2009, mentions a wels catfish dragging a fisherman near Győr, Hungary, under water by his right leg after he attempted to grab the fish in a hold. The man barely escaped from the fish, which he estimated to have weighed over 100 kg (220 lb).[16]
Diet
Like most freshwater bottom feeders, the wels catfish lives on
The wels catfish has also been observed taking advantage of large die-offs of Asian clams to feed on the dead clams at the surface of the water during the daytime. This opportunistic feeding highlights the adaptability of the wels catfish to new food sources, since the species is mainly a nocturnal bottom-feeder.[21]
Distribution and ecology
The wels catfish lives in large, warm lakes and deep, slow-flowing rivers. It prefers to remain in sheltered locations such as holes in the riverbed, sunken trees, etc. It consumes its food in the open water or in the deep, where it can be recognized by its large mouth. Wels catfish are kept in fish ponds as
An unusual habitat for the species exists inside the Chernobyl exclusion zone, where a small population lives in abandoned cooling ponds and channels at a close distance to the decommissioned power plant. These catfish appear healthy, and are maintaining a position as top predators in the aquatic ecosystem of the immediate area.[22]
As introduced species
There are concerns about the ecological impact of introducing the wels catfish to regions where it is not native. Following the introduction of wels catfish, populations of other fish species have undergone steep declines. Since its introduction in the Mequinenza Reservoir in 1974, it has spread to other parts of the Ebro basin, including its tributaries, especially the Segre River. Some endemic species of Iberian barbels, genus Barbus in the Cyprinidae that were once abundant, especially in the Ebro river, have disappeared due to competition with and predation by wels catfish.[citation needed] The ecology of the river has also changed, with a major growth in aquatic vegetation such as algae.
The wels catfish may have established a population in Santa Catarina, Brazil.[23] They were imported from Hungary in 1988 and were washed into the Itajaí-Açu river after a flood caused their tanks to overflow. In 2006, a specimen weighing 86 kg (189.5 lbs) and 1.85 m (6 ft) long was captured in Blumenau, suggesting the catfish have survived and possibly be reproducing.
Conservation status
Although Silurus glanis is not considered globally endangered, the conservation status varies across the species native distribution range. In the northern periphery of the distribution, the species has been declining over the last centuries and was extinct from Denmark in the 1700s and from Finland in the 1800s.[24] In Sweden it persists only in a few lakes and rivers, and is now considered as near threatened.[25] Recent genetic studies have furthermore found that the Swedish populations harbors low genetic diversity and are genetically isolated and differentiated from each other,[24][26] highlighting the need for conservation attention.
As food
Wels catfish can be provoked to bite a lure by the sound of a piece of wood plunging into the water, the clonk.
Attacks on people
Tabloids regularly report attacks caused by various catfish that primarily affected animals (often only the role of the catfish was presumed). In April 2009, an Austrian fisherman was allegedly attacked by a catfish in one of the fishing lakes in Pér, near Győr, Hungary. However, the man reportedly managed to break free.[27]
The Wels was the subject of an episode in the first season of the documentary television show River Monsters. Host Jeremy Wade concluded that Wels catfish in the area were not large enough to consume adult human beings, but could easily swallow a child. Wade documented instances of Wels catfish being aggressive towards humans, including a Wels he had just caught that "double[d] round" and attempted to bite his calf.[28]
Similar stories occur in the works of older natural history writers. Alfred Brehm (1829–1884), a German naturalist, published his famous work The World of Animals in the 19th century. It was also translated into Hungarian at the beginning of the 20th century. In this, Brehm or the compiling Hungarian scientists write the following:
- "Old Gesner’s (Conrad Gessner Swiss naturalist, 1516–1565) claim that catfish doesn’t spare humans either doesn’t just belong in the realm of tales, as we know of several cases that confirm that. Thus, Heckel and Kner mention that a catfish was caught at Bratislava, in the stomach of which the remains of a child corpse were found. [...] Fishermen credible to Antipa (probably Romanian zoologist Grigore Antipa, 1866–1949) told me that children bathing in the stomachs of catfish were caught in the bones of their hands and feet. - Communicates Vutskits (probably Hungarian zoologist hu:Vutskits György, 1858–1929). - A Romanian fisherman penetrated the middle of the Danube with his boat because he wanted to take a bath. While bathing, a catfish caught his legs, which he could no longer pull out of the mouth of this big-mouthed monster, and so he got to the bottom of the water. A few days later, they came across the corpse of a dead fisherman whose legs were still in the catfish's mouth, but even the greedy robber could not release his victim's legs and drowned because of it".[29]
Related species
- Aristotle's catfish (Silurus aristotelis) from Greece, the only other native European catfish species beside Silurus glanis.
- Amur catfish (Silurus asotus), introduced to European rivers
- Giant Lake Biwa catfish (Silurus biwaensis) from Japan endemic to Lake Biwa.
- Amur River, Russia
See also
References
- . Retrieved 12 November 2021.
- ^ ISBN 978-1-139-45181-9. Retrieved 13 January 2022.
- ^ Bergström, K., Nordahl, O., Söderling, P. et al. Exceptional longevity in northern peripheral populations of Wels catfish (Silurus glanis). Sci Rep 12, 8070 (2022). https://doi.org/10.1038/s41598-022-12165-w
- ^ Froese, Rainer; Pauly, Daniel (eds.) (2016). "Silurus glanis" in FishBase. February 2016 version.
- ^ Brehm, Alfred; Brehms Tierleben II - Fish, Amphibians, Reptiles 1
- ^ Mareš, Jaroslav; Legendární příšery a skutečná zvířata, Prague, 1993
- ^ Ottó Hermann: A Book of Hungarian Fishing (A magyar halászat könyve), p. 340, [1]
- ^ Slavica Stuparušić (22 June 2018). "Уловљен џиновски сом на Гружанском језеру" [Gigantic wels catfish caught in the Gruža Lake]. Politika (in Serbian). p. 08.
- ^ N.Radišić (21 June 2018). "Dolijala zver iz Gružanskog jezera: izvukli soma od 2,4 metra i 117 kilograma na tri zrna kukuruza" [The beast from the Gruža Lake came about - they caught a 2,4 m long and 117 kg heavy wels catfish]. Blic (in Serbian).
- ^ Archived at Ghostarchive and the Wayback Machine: "275cm WORLD RECORD SILURO -- SPINNING - MONSTER CATFISH 275cm 117kg". YouTube.
- ^ "IGFA Member Services".
- ISBN 0-85112-235-3.
- ^ "Világrekord méretű harcsa a Dunából | Hírek | Fishing Time Horgászmagazin és Horgász Áruház".
- ^ "Под Черкассами поймали гигантского сома: весит 140 кг (фото)".
- ^ Sascha Pare (15 June 2023). "Gigantic, 9.4-foot-long catfish is the largest ever caught". livescience.com. Retrieved 19 August 2023.
- ^ Der Standard, 2009-08-05. Waller-Wrestling im ungarischen Fischerteich. Retrieved 2009-08-06. (in German)
- ^ Slone, C. (2006). "Silurus glanis Danube catfish". Animal Diversity Web. University of Michigan, Museum of Zoology.
- ^ Sieczkowski, Cavan (8 December 2012). "Catfish Hunt Pigeons: Fish Catch Birds on Land in Display of Adaptive Behavior (VIDEO)". The Huffington post. Retrieved 16 March 2017.
- PMID 23227213.
- ^ Yong, Ed. "The catfish that strands itself to kill pigeons". Discover Magazine. Retrieved 16 March 2017.
- ^ "The European catfish loves Asian clam soup | Société Française d'Ichtyologie - Cybium". sfi-cybium.fr. Retrieved 5 March 2021.
- ^ Keartes, Sarah. "Yes, there are giant catfish in Chernobyl's cooling pond – but they're not radiation mutants". Earth Touch. Retrieved 14 April 2019.
- – via ResearchGate.
- ^ S2CID 204028931.
- ^ "Artfakta från SLU Artdatabanken". artfakta.se (in Swedish). Retrieved 10 May 2021.
- PMID 33963302.
- ^ Balázs, Laczó (6 July 2009). "Óriásharcsa támadt a horgászra" [Giant catfish attacks fisherman]. kisafold.hu (in Hungarian). Archived from the original on 27 September 2020.
- ^ Wade, Jeremy. “Chapter 2: Wels.” River Monsters: True Stories of the Ones That Didn't Get Away, Da Capo Press, a Member of the Perseus Books Group, Boston, MA, 2012, pp. 34–49.
- ^ Brehm, Alfred. "Leső harcsák (Silurus Art.)" [Catfish (Silurus Art.)]. Az Állatok Világa [The World of Animals] (in Hungarian). Retrieved 30 June 2022.
Further reading
- Freyhof, J.; Kottelat, M. (2008). "Silurus glanis". . Retrieved 12 November 2021.
- "Silurus glanis". Integrated Taxonomic Information System. Retrieved 19 March 2006.