|Scope: Global & Europe|
|Scientific Name:||Agonus cataphractus (Linnaeus, 1758)|
Cottus cataphractus Linnaeus, 1758
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Florin, A., Keskin, Ç., Lorance, P. & Herrera, J.|
Agonus cataphractus is restricted to coastal regions of the northwest Atlantic and reaches as far as the Arctic region of the White Sea. Agonus cataphractus primarily occurs over soft bottom substrates such as sand, mud, and gravel to 270 m depth. This species has experienced decreases in population in areas of the North Sea due to anthropogenic impacts; however, increases in average abundance have been observed in the past few decades due to improvements to waste water facilities which have reduced the amount of organic pollution in the Thames estuary. Agonus cataphractus is relatively short lived and most individuals only reproduce once at the age of one year; populations of A. cataphractus are likely able to rebound quickly from disturbances. Therefore, Agonus cataphractus is assessed as Least Concern.
|Range Description:||Agonus cataphractus occurs in coastal areas of the northeastern Atlantic Ocean (Wheeler 1969). It barely reaches the arctic region in the White Sea and occurs off Jan Mayen, in the Barents Seas, Norwegian Sea, Baltic Sea, and the English Channel (Wienerroither et al. 2010, Kanayama 1991). The depth range for A. cataphractus is 35 m to 270 m (Kanayama 1991).|
Native:Belgium; Denmark; Estonia; Finland; France (France (mainland)); Germany; Guernsey; Jersey; Latvia; Lithuania; Netherlands; Norway; Poland; Russian Federation (European Russia, Kaliningrad, Northwest European Russia); Svalbard and Jan Mayen; Sweden; United Kingdom (Great Britain)
|FAO Marine Fishing Areas:|
Atlantic – northeast
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Between a 1977 and 1992 sampling period, 3,074 individuals of A. cataphractus were captured in the Thames estuary. This species occurred in 55.4% of all samples and accounted for 0.52% of all the marine fishes sampled. The abundance of this species peaked in December and March to April with a marked decline in abundance in February of each year. Agonus cataphractus was found to be absent from the middle reaches of the estuary between early June and mid September (Power and Attrill 2002). |
This species was reported to be one of three most common species found in trawls of the outer Thames estuary in the early 1960s. Agonus cataphractus was reported occasionally in samples by the late 1960s and by the 1970s this species was commonly observed in West Thurrock samples (Wheeler 1963, Andrews and Rickard 1980, Huddart and Arthur 1971, Wheeler 1979).
Biomass of this species based on catches from the English Groundfish Survery did not show any significant trends between 1977 and 1986 (Daan et al. 1990). Sample abundances rose from 4.2 individuals per sample between 1977 and 1982, to 13.5 individuals per sample between 1983 and 1989 (Power and Attrill 2002). An exception to the overall increasing trend was observed in 1985 when abundances of this species fell significantly. This event is suspected to be due to abnormally low surface temperatures recorded during the winter of 1984 to 1985 (Power and Attril 2002).
Agonus cataphractus was ranked at the ninth most abundant species and the fourth most frequently encountered species in the Forth estuary. This species was also found to be common in the lower Blyth estuary (Elliott and Taylor 1989, David and Dunn 1982). Agonus cataphractus was determined to be slightly more abundant in the middle Thames estuary than in the adjacent lower Medway estuary where this species was ranked as the 21st most abundant species sampled and comprised only 0.1% of all fish sampled (van den Broek 1979, 1980). Between 1901-1907 and 1993-1997 the catch rate appears to have sharply increased (Rijnsdorp et al. 1996).
|Current Population Trend:||Increasing|
|Habitat and Ecology:||Agonus cataphractus is a coastal species that is found over soft substrates including sand, mud and gravel. This species can grow up to about 15 cm and is short lived with a life span of three to four years. Common prey items of A. cataphractus include juvenile crabs (Carcinus maenus), shrimp (Crangon crangon) and amphipods (Grammarus spp.). Agonus cataphractus undertake a seasonal migration in the southern parts of its distribution to shallower waters and are commonly found in estuaries in winter months (Wheeler 1969).|
Agonus cataphractus is known to spawn in late autumn and early winter in shallow water but may occur as early as October in the French Atlantic coast (Wheeler 1969, Le Gall 1969). Agonus cataphractus usually only reproduce once at age one plus and it has been suggested that a reproductive advantage is gained when this species uses the warmer estuarine waters rather than cooler waters of the North Sea (Le Gall 1969, Power and Attrill 2002). Females deposit the demersal eggs in the alga which can range from 1.7 mm to 2.2 mm (Kanayama 1991, Washington et al. 1984) Peak occurrences of this species reported from November to January along the English east coast would coincide with an inshore spawning migration but could also be associated with seasonal use of preferred prey species such as age zero flat fish and decapod crustaceans known to peak in abundance between December and January (Attrill et al. 1999, Power et al. 2000).
Agonus cataphractus can be found in a wide range of salinities which suggests that this species has a physiological tolerance more characteristic of a euryhaline species than that of a strictly stenohaline species. The additional metabolic costs of osmotic and ionic regulation required in varying salinities will reduce growth unless compensated by increased feeding opportunities (Power and Attril 2002, Wootton 1990). This species is commonly associated with dab and sole in flatfish nursery areas (Riley et al. 1981).
|Use and Trade:||Agonus cataphractus is a non-commercial species (Power and Attrill 2002).|
|Major Threat(s):||Agonus cataphractus is susceptible to anthropogenic impacts in the North Sea as it inhabits coastal and estuarine habitats. These threats may include eutrophication, coastal erosion, landfill, run-off from urban and industrial activities and waste water. The Seine, Rhine Meuse complex, Scheldt, Weser, Elbe, Humber and Thames basins are of the most heavily industrialized regions in the world (Power and Attril 2002, Ducrotoy et al. 2000).|
|Conservation Actions:||Increased average annual abundances of A. cataphractus have been observed in the past few decades due to the reduction of organic pollution associated with the upgrade of major sewage technologies in the Thames estuary (Andrews 1984, Power and Attrill 2002).|
|Citation:||Florin, A., Keskin, Ç., Lorance, P. & Herrera, J. 2014. Agonus cataphractus. The IUCN Red List of Threatened Species 2014: e.T18227168A44721374.Downloaded on 15 October 2018.|