Analysis of the biological features of the goldfish Carassius auratus auratus in Lake Trasimeno (Umbria, Italy) with a view to drawing up plans for population control
Lorenzoni, M.,University of Perugia (Italy). Dept. of Cellular and Environmental Biology | Ghetti, L.,Hunting and Fishing Service, Perugia (Italy) | Pedicillo, G.,University of Perugia (Italy). Dept. of Cellular and Environmental Biology | Carosi, A.,University of Perugia (Italy). Dept. of Cellular and Environmental Biology
The growth and reproductive biology of the invasive goldfish Carassius auratus auratus were studied in Lake Trasimeno, central Italy. The results of the research revealed that the population is made up of eight age-classes. The sex ratio proved to be extremely unbalanced (1 : 19 in favour of females). Growth can be deemed rapid as shown by the von Bertalanffy equation. No sexual dimorphism in growth was observed. Back-calculation analysis suggested the existence of an inverse Lee phenomenon among 1 year-old specimens. The reproductive period covers a broad time-span, from March to June. In females, sexual maturity is reached after the second winter of life (2 age-class); however, a small percentage (7.55%) of females is able to reproduce at the age of 1 year. Most of the males attained sexual maturity in the first year (60.61%). The reproductive investment of the females is high. Fecundity varied from 286 to 219,104 eggs, with an average relative fecundity of 103+/-5 eggs/g; the mean diameter of the eggs was 1.27+/-0.01 mm. The reproductive investment of the females was not homogeneous across the age-classes; in addition to absolute fecundity, relative fecundity and egg diameter were seen to increase with the size of the specimens.
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