Status of the crucian carp, Carassius carassius (L.), in the UK

Abstract

Summary The crucian carp, Carassius carassius (L.), is a small fish of restricted distribution in the UK, which is probably only native to central and eastern England. The crucian carp is endemic to northern Europe. It has been widely confused with the introduced and congeneric goldfish, Carassius auratus (L.), and forms hybrids with that species and the introduced Cyprinus carpio L. The status of this fish has become confused with the presence of the congener and its hybrids, and it is now thought to be less frequent in occurrence than formerly.

Growth and morphology of an endangered native freshwater fish, crucian carp Carassius carassius, in an English ornamental pond

“…This includes the crucian carp Carassius carassius (e.g. Holopainen and Pitkanen, 1985;Copp, 1989Copp, , 1991Nicolas and Pont, 1995;Wheeler, 1998Wheeler, , 2000, a cryptic benthic species that feeds on bottom-dwelling invertebrates such as Diptera (mainly Chironomidae, Ceratopogonidae), Ostracoda, Hydracarina and Gastropoda (Guti et al, 1991). The native distribution of crucian carp encompasses much of north and central Europe (e.g.…”

“…The native distribution of crucian carp encompasses much of north and central Europe (e.g. Lelek, 1980), including south-eastern England (Wheeler, 2000). Presumed to have been introduced along with the common carp Cyprinus carpio, crucian carp was previously classed as non-native to the British Isles (e.g.…”

“…However, archaeological evidence (Lever, 1977;Newdick, 1979) and the similarity of crucian carp's pre-1960s distribution to that of other native cyprinids led Wheeler (1977) to re-classify the species as native to south-eastern England (see also Wheeler et al, 2004). Indeed, Wheeler's (1998Wheeler's ( , 2000 studies highlighted the threat to crucian carp posed by introductions of goldfish Carassius auratus, which hybridize with, and may eventually replace, crucian carp (Wheeler, 2000;Smartt, 2001;Ha¨nfling et al, 2005).…”

“…The current distribution of crucian carp in Britain remains unclear. The brown variety of goldfish is often mistakenly identified as crucian carp (Wheeler, 2000;Hickley and Chare, 2002), raising questions about the reliability of existing distribution maps (e.g. Davies et al, 2004;Maitland, 2004).…”

“…To address this paucity of autecological data, the aim of this present study was to provide the first detailed information on the growth of crucian carp in Britian, using specimens from the same population (Bayfordbury Lake, Hertfordshire) that provided the morphotype for Wheeler's (2000) study and that still remains pure crucian carp. The specific objectives of the study were: (1) to determine the length and age at maturity; and (2) to evaluate the relative growth of mensural (morphological) characters and backcalculated longitudinal growth from specimens collected in 1995 and compare them with existing published data from elsewhere in Europe.…”