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

Abstract

ABSTRACT1. Crucian carp Carassius carassius, which is native to south-east England, has received little previous study in Britain but is threatened by introductions of goldfish Carassius auratus through hybridization and by frequent mis-identification of brown goldfish as crucian carp. The present study provides the first data on back-calculated growth, morphology and age-at-maturity of crucian carp in Britain.2. The youngest mature crucian were female (age 2þ), the smallest mature crucian were male (age 3þ), with almost all fish mature at age 3 þ : Sex dimorphism in back-calculated standard length at age was not observed except at age 2þ (juveniles longest). Shifts in morphological characters often associated with maturation (dorsal and ventral fin length, dorsal and anal fin depth, pre-dorsal distance, body width) were observed between ages 4þ and 7þ; which (in contrast to the relatively abrupt shift in maturity) suggests that age and size at maturation may not reflect the size and age of active (i.e. real) spawning.3. Back-calculated standard lengths at age for crucian carp were intermediate relative to other European populations, indicating that environmental conditions in England appear to be well suited to the species despite being at the westernmost extent of the species' native European range. The management of ornamental ponds specifically for crucian carp is discussed.

Influence of stocking density and type of feed on the rearing of crucian carp, Carassius carassius (L.), larvae under controlled conditions

“…For many years, this species (due to its flexibility) has been the subject of many scientific studies (e.g. Skrzypczak and Mamcarz 2005;Copp et al 2008;Tarkan et al 2009). However, data on the biological aspects of rearing the larvae of this species under controlled conditions as stocking material is fragmentary.…”

Growth and reproduction of threatened native crucian carp Carassius carassius in small ponds of Epping Forest, south‐east England

“…However, no relationship was observed between food availability and growth, which in both crucian carp (Table 2) and goldfish (Tarkan et al, unpublished data) was observed to be faster, especially with respect to older age classes, when the two species live in sympatry (in low abundance) rather than in allopatry (in higher abundance). The slowest growth of crucian carp reported for England was in Lake Bayfordbury, which contains no goldfish and a relatively low density of crucian carp (Copp et al, 2008a) but food resources did not appear to be limiting (Copp et al, 2008b). Co-existence of these congeners may provoke a maximization of somatic growth potential (growth rate and plumpness), which in crucian carp is known to be adversely affected by intra-specific competition when the food shortage increases (Holopainen et al, 1997).…”

“…This is consistent with results of Szczerbowski et al (1997) for water bodies (Lake Sumo´wko and Forest ponds) in Poland (Szczerbowski et al, 1997) as well as for crucian carp in Bayfordbury Lake, which is o30 km north of the Epping Forest ponds. In Bayfordbury Lake, mature females were reported at age 21 and virtually all females mature by age 31 (Copp et al, 2008a), although the specimens were sampled too late in the year to assess length and age at maturity. In Turkey, which is the southernmost extent of the species' introduced range, age 21 has also been the reported age at maturity for the species (Becer et al, 1998;Cetinkaya et al, 1999).…”

“…Despite its native status in the UK, the natural history of crucian carp in England has received little study, and this has been limited to growth (Marlborough, 1967;Copp et al, 2008a,b), with age at maturity the only mention of the species' reproduction (Copp et al, 2008a). Recently recognized as a threatened species (Smith and Moss, 1994;Environment Agency, 2003), the crucian carp is also of particular biological interest because populations in England represent the most western extent of the species native range.…”

Management of an ornamental pond as a conservation site for a threatened native fish species, crucian carp Carassius carassius

“…Fish assemblage monitoring began in October 1992 (first and last weeks) and took place annually until 2000 using fyke nets, seine netting and electrofishing (see Copp et al, 2007). Fish were measured for standard length (SL) in mm and wet body weight (nearest g) and returned to the water.…”