Growth and reproductive properties of Tench,Tinca tincaLinnaeus, 1758 in Trasimeno Lake (Umbria, Italy)

Abstract

Key-words:von Bertalanffy's parameters, back calculation, reproduction, fecundity, gonadosomatic index Growth and some reproductive properties of native Tinca tinca Linnaeus, 1758 from Trasimeno Lake were investigated during 2009 and 2010. The total sample of fish (510) was composed by 126 males, 221 females and 163 immature specimens. Total length (TL ± 0.1 cm) and weight (W ± 0.1 g) were recorded; age estimation was based on scalimetry and sex was determined by microscopic observation of the gonads. Age composition varied from 1+ to 11+. The TL-W relationship was log 10 W = −2.235 + 3.248 log 10 TL. Previous growth was determined with back-calculation from scale measurements using the Fraser-Lee method. Theoretical length growth was estimated with von Bertalanffy's model. Analysis of the gonadosomatic index (GSI) suggests that the reproductive period of the population took place from May to July. Sexual maturation occurred in both sexes at the second year of life. The mean diameter of eggs was 0.075 mm. The mean number of eggs produced by each female was 233 930 and increased with the size of the specimens. Though it is one of the most widespread and interested species in fishing in Italian waters, tench has not been widely studied; this research deepens some biological characteristics of this species that is strongly shrinking in Italy. La longueur totale (TL ± 0,1 cm) et le poids (W ± 0,1 g) ont été enregistrés ; l'estimation de l'âge a été faite par scalimétrie et le sexe a été déterminé par l'observation microscopique des gonades. La composition en âge variait de 1+ à 11+. La relation TL-W était log 10 W = −2, 235 + 3,248 log 10 TL. La croissance a été détermi-née par rétro-calcul à partir de mesures sur les écailles en utilisant la méthode de Article published by EDP Sciences L. Pompei et al.: Knowl. Managt. Aquatic Ecosyst. (2012) 406, 07 Fraser-Lee. La croissance en longueur théorique a été estimée avec le modèle de von Bertalanffy. L'analyse de l'indice gonadosomatique (GSI) suggère que la période de reproduction de la population a lieu de mai à juillet. La maturation sexuelle a eu lieu dans les deux sexes dès la deuxième année de vie. Le diamètre moyen des oeufs était de 0,075 mm. Le nombre moyen d'oeufs produits par chaque femelle était 233 930 et augmentait avec la taille des spécimens. Bien qu'elle soit l'une des espèces les plus répandues et recherchées par la pêche dans les eaux italiennes, la tanche n'a pas été largement étudiée ; cette recherche approfondit certaines caractéristiques biologiques de cette espèce qui est en forte régression en Italie. RÉSUMÉ

Age, growth and body condition of big-scale sand smeltAtherina boyeriRisso, 1810 inhabiting a freshwater environment: Lake Trasimeno (Italy)

“…Lake Trasimeno is listed as a Site of Community Interest (SCI) and Special Protection Area (SPA) within the Natura 2000 European network and it was assessed as a Regional Park. The lake is characterised by a Mediterranean climate and its seasonal level is quite variable (in 2012 from −92 cm to −154 cm during summer relative to the reference level) because water is supplied by short intermittent streams that tend to dry up during the summer season (Pompei et al, 2012b). The water temperature is almost the same as the air temperature, and in summer it can exceed 30 • C; thermal stratification is usually absent (Lorenzoni et al, 2002b).…”

Nutritional composition of raw and fried big-scale sand smelt (Atherina boyeri) from trasimeno lake

“…As has already occurred for other species in Italian lakes, it is fundamental to define the nutritional characteristics of the fish to valorise them and their relative products (Dal Bosco et al 2010Pompei et al 2012;Franceschini et al 2015;Mattioli et al 2017). Indeed, the disappearance of local productive companies indicates losses, not only at the economic level, but also from historical, social and cultural points of view.…”

Length-weight relationships of three fish species from Trasimeno Lake, Italy

“…Other alien species such as Carassius auratus (Linnaeus, 1758) and Pseudorabora parva (Temminck and Schlegel, 1846) are invasive and considered as dangerous to the ecosystem (Giannetto et al., ; Lorenzoni, Corboli, Ghetti, Pedicillo, & Carosi, ). In recent years, the populations of native species Esox cisalpinus Bianco & Delmastro, and Tinca tinca (Linnaeus, 1758) showed a strong reduction in abundance (Pompei, Franchi, Giannetto, & Lorenzoni, ; Pompei et al., ). Degradation of the breeding areas is also affecting the abundance of E. cisalpinus , with the reproduction of the species actually widely supported by controlled spawning carried out by the Ichthyogenic Centre of Trasimeno Lake.…”