Reproductive biology of Cisalpine pike (Esox cisalpinus Bianco & Delmastro, 2011) in the Lake Trasimeno (Italy)

The aim of this study was analysis of the data on the reproductive biology of the endemic Esox cisalpinus from Lake Trasimeno (central Italy). Data were collected with gillnets (mesh sizes 50–100 mm) from 2010 to 2014 during the reproductive period of the species. Fish age was assessed by scalimetric method and their condition evaluated by relative condition factor. Gonado-Somatic Index, fecundity, relative fecundity and egg sizes were calculated. A total of 1,543 specimens (862 females, 681 males) ranging in size from 28.0 to 103.0 cm were examined. Age composition ranged from 2+ to 12+. Both males and females matured at 2 years of age, at 28 cm total length. Fecundity ranged from 1,540 to 160,300 eggs; mean relative fecundity was 18,815 eggs/kg. Males and females were all found to be in good condition, with the relative fecundity increasing with improvements in their body condition