Reproductive properties of the chub Squalius squalus (Bonaparte, 1837) in the Assino Creek (Umbria, Italy)
2011
Lorenzoni M. | Carosi A. | Pedicillo G. | Pompei L. | Rocchini M.
This study investigated the reproductive properties of the population of chub Squalius squalus (Linnaeus, 1758) in the Assino creek, one of the largest tributaries of the upper course of the River Tiber. A total of 547 specimens were caught monthly from March 2008 to May 2009. The age composition of the sample ranged between 0+ and 11+. The sample was made up of 64.54% males and 35.46% females; sexual maturity was attained in both sexes in the second year of life. Analysis of the gonado-somatic index (GSI) and of the stage of gonad maturation throughout the year suggests that the reproductive period of the population extends over a long time (April–July). The relationship between total length and fecundity was F = 5.466TL2.312. The mean number (±SE) of eggs produced by each female was 15 351 ± 1705 and increased with the size and age of the specimens; with regard to relative fecundity, an average value (±SE) of 53 553 ± 4098 eggs·kg-1 was observed. The mean diameter (±SE) of ripe eggs was 0.117 ± 0.004 cm. This study sheds light on some important characteristics of the reproductive biology of the chub that have not been fully investigated in Italian populations.
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