The goldfish Carassius auratus (Linnaeus, 1758) is indigenous to eastern Asia; since its introduction in the late 1990s, it has become established in Lake Trasimeno (Umbria, Italy), where it is now very abundant owing to the absence of predators, including man. This species displays a potentially invasive behaviour, owing to some ecological and biological characteristics: high tolerance of water pollution, high fecundity rate and wide-ranging diet. It exerts a negative impact on fish communities, mostly due to inter-specific competition. Biological data on Italian goldfish populations are scarce. The aim of this study was to collect data on the growth and reproductive biology of this species, in order to investigate the causes of its rapid expansion in Lake Trasimeno. Sampling was carried out monthly, from February 2003 to January 2004; the total sample comprised 3 111 specimens captured by means of electrofishing and multi-mesh nets. Results showed that the population of goldfish in Lake Trasimeno was composed mostly of females (97.4% of the total sample). Most (85%) of the females attained sexual maturity in their 2nd year, but a small percentage (7.55%) was already able to spawn in the 1st year. Fecundity varied from 286 to 219 104, averaging 46 253 eggs; the diameter of mature eggs ranged from 0.74 to 1.71 mm, with a 1.27 mm average. Average relative fecundity was 103 eggs g-1. The catching ability of the various sampling methods was compared in order to design a programme to control the density of the unwanted populations.
Growth and reproduction of the goldfish Carassius auratus: a case study from Italy.
LORENZONI, Massimo;CORBOLI, MASSIMILIANO;PEDICILLO, GIOVANNI;CAROSI, Antonella
2007
Abstract
The goldfish Carassius auratus (Linnaeus, 1758) is indigenous to eastern Asia; since its introduction in the late 1990s, it has become established in Lake Trasimeno (Umbria, Italy), where it is now very abundant owing to the absence of predators, including man. This species displays a potentially invasive behaviour, owing to some ecological and biological characteristics: high tolerance of water pollution, high fecundity rate and wide-ranging diet. It exerts a negative impact on fish communities, mostly due to inter-specific competition. Biological data on Italian goldfish populations are scarce. The aim of this study was to collect data on the growth and reproductive biology of this species, in order to investigate the causes of its rapid expansion in Lake Trasimeno. Sampling was carried out monthly, from February 2003 to January 2004; the total sample comprised 3 111 specimens captured by means of electrofishing and multi-mesh nets. Results showed that the population of goldfish in Lake Trasimeno was composed mostly of females (97.4% of the total sample). Most (85%) of the females attained sexual maturity in their 2nd year, but a small percentage (7.55%) was already able to spawn in the 1st year. Fecundity varied from 286 to 219 104, averaging 46 253 eggs; the diameter of mature eggs ranged from 0.74 to 1.71 mm, with a 1.27 mm average. Average relative fecundity was 103 eggs g-1. The catching ability of the various sampling methods was compared in order to design a programme to control the density of the unwanted populations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
