Size selectivity of gill-nets and growth of roachRutilus rutilus(Linnaeus, 1758) an alien species in Piediluco lake (Italy)

Abstract

Key-words:growth, gill-net selectivity, alien species, euthrophic lake, fisheries managementThe analysis of catch selectivity of fishing equipment is a crucial step for the management of alien species in freshwater ecosystems. Roach Rutilus rutilus was introduced in many waterways in Italy often becoming the dominant species of the fish community and it is now considered potential pest. In Piediluco lake the species was first found in 2004 and its abundance has increased at a level that creates concern for the other fish species present in the lake. The growth of R. rutilus and the selectivity of gill-nets on its population were examined in Piediluco lake by analysing the selectivity of gill-nets of different mesh size. Sampling was conducted from January 2011 to October 2012 by means of gill-nets of differentsized mesh (8, 10, 12.5, 15.5, 19.5, 24, 28, 35, 45 and 55 mm). The results showed that R. rutilus in Piediluco lake had a growth faster and higher than in many other lake environments. The results of gill-nets selectivity gave important information to design a plan to control this species and confirmed that the use of suitable fishing techniques could be useful to manage the population of this alien species in Piediluco lake as well as in other similar environments. RÉSUMÉSélectivité en taille des filets maillants et croissance du gardon Rutilus rutilus (Linnaeus, 1758), une espèce exotique au lac de Piediluco (Italie) Mots-clés :croissance, sélectivité, filet maillant, espèce exotique, lac eutrophe, gestion des pêches L'analyse de la sélectivité des captures du matériel de pêche est une étape cruciale pour la gestion des espèces exotiques dans les écosystèmes d'eau douce. Le gardon Rutilus rutilus a été introduit dans de nombreux cours d'eau en Italie, devenant souvent l'espèce dominante de la communauté de poissons et il est maintenant considéré comme nuisible potentiel. Dans le lac de Piediluco l'espèce a été découverte en 2004 et son abondance a augmenté à un niveau qui suscite des inquiétudes pour les autres espèces de poissons présents dans le lac. La croissance de R. rutilus et la sélectivité des filets maillants sur la population ont été examinées au lac de Piediluco par l'analyse de la sélectivité des filets maillants de maillages différents. L'échantillon-nage a été effectué de janvier 2011 à octobre 2012 au moyen de filets maillants de différentes mailles (8, 10, 12.5, 15.5, 19.5, 24, 28, 35, 45 et 55 mm). Les résultats ont montré que R. rutilus du lac de Piediluco a connu une croissance plus rapide et plus élevée que dans beaucoup d'autres milieux lacustres. Les ré-sultats de la sélectivité des filets maillants ont donné des informations importantes pour concevoir un plan pour contrôler cette espèce et a confirmé que l'utilisation de techniques de pêche appropriées pourrait être utile pour gérer la population de cette espèce étrangère dans le lac de Piediluco, ainsi que dans d'autres environnements similaires.

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

“…However, in comparison to goldfish (Carassius auratus) from Trasimeno Lake, the oxidative state of sand smelt (Dal Bosco et al 2010;Dal Bosco et al 2012) that were fished during the same time of year was worse. Such different oxidative statuses are mainly related to the feeding behaviours of these fishes; bigscale sand smelt show a more pronounced oxidative muscular metabolism and are exclusively carnivorous fish, and conversely goldfish are omnivores (Dal Bosco et al, 2012;Giannetto et al, 2014). As consequence, the big-scale sand smelt is more exposed to oxidative risk and it does not intake enough antioxidants (algae or marine plants) like the goldfish.…”

Occurrence and distribution of exotic fishes in the Tiber River basin (Umbria, central Italy)

“…In Lake Piediluco, the roach appeared in 2004 (La Porta et al., ), is well acclimatized, and is currently one of the most abundant species. During monitoring in 2011–2012, R. rutilus represented 35.20% of the total biomass of fish caught (Giannetto et al., ).…”

“…T A B L E 4 Summary statistics of environmental parameters for sampling sites where Rhodeus sericeus was present, sampled once in autumn for each census period (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) (Giannetto et al, 2014).…”

First information on age and growth ofPadogobius bonelli(Bonaparte, 1846) outside of its native range: River Aggia (Central Italy)

“…P. bonelli is counted as one of the main threats to the survival of the congeneric P. nigricans, a species endemic to Central Italy, due to: aggressive behaviour and competition for premium reproductive territory (Gandolfi et al 1991;Zerunian, 2004;Mecatti et al, 2010), competition for feeding resources and a higher allocation of energy in reproduction compared to P. nigricans Pompei et al, in press.). A full understanding of life history characteristics of alien species is crucial to assess their possible ecological impact on ecosystems, to predict their invasive potential (Ricciardi and Rasmussen, 1998;Guo et al, 2013;Grabowska et al, 2011;Hôrková and Kováè, 2013) and propose effective management strategies (Guo et al, 2013;Yeates et al, 2012;Giannetto et al, 2014). Although the severe ecological impact of P. bonelli on native species is wide known, to date, any study on age and growth of non-native populations of P. bonelli out of its native range has ever been conducted and basic information on the reproductive biology of this species outside of its native range is only recently available (Pompei et al, in press).…”