Entity

Time filter

Source Type

Terni, Italy

Pedicillo G.,University of Perugia | Lorenzoni M.,University of Perugia | Carosi A.,Provincia di Terni | Ghetti L.,Regione dellUmbria
North American Journal of Fisheries Management | Year: 2013

Stock-density indices are standardized methods for analyzing length-frequency data that quantify the length structure of a fish population into length categories that are of interest to recreational anglers. We adapted North American relative stock density (RSD) and proportional stock density (PSD) indices to four Italian endemic or native cyprinid species by means of two methods. In accordance with the traditional approach, the benchmarks of length categories were established according to Gabelhouse's percentage classification and calculated on the basis of the largest individual in the data set for each species. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from fish collected from sampling sites in the Tiber River basin. The results showed that the traditional approach displayed better applicability, required less sampling effort, and provided a better insight into the length structure of the fish populations studied. © 2013 Copyright Taylor and Francis Group, LLC. Source


Pedicillo G.,University of Perugia | Carosi A.,Provincia di Terni | Ghetti L.,Regione dellUmbria | Lorenzoni M.,University of Perugia
Knowledge and Management of Aquatic Ecosystems | Year: 2010

The purpose of this study was to provide reference data on the growth and population structure of brown trout Salmo (trutta) trutta Linnaeus, in Central Italy. Standards for growth (percentiles and a standard growth model) were developed from the von Bertalanffy growth model by using length-at-age data obtained from 122 sampling sites in the River Tiber basin. Length-frequency indices provide a numeric estimation for deviations of the population structure from a balanced population. We adapted the traditional North American Relative Stock Density (RSD) and Proportional Stock Density (PSD) indices to brown trout populations in Central Italy by means of two methods. In the first method, the benchmarks of length categories were established by using percentages applied to the largest individual in the dataset. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from 263 sampling sites in the River Tiber basin. The results showed that the PSD calculated by the first method provided a better insight into the population structures of brown trout. These results provide tools that will help ichthyologists and fish managers to compare the growth and population structure of brown trout throughout Central Italy. © ONEMA, 2010. Source


Giannetto D.,University of Perugia | Carosi A.,Provincia di Terni | Ghetti L.,Regione dellUmbria | Pompei L.,University of Perugia | And 2 more authors.
Knowledge and Management of Aquatic Ecosystems | Year: 2014

The 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 different-sized 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. © 2014 ONEMA. Source


Giannetto D.,University of Perugia | Carosi A.,Provincia di Terni | Ghetti L.,Regione dellUmbria | Pedicillo G.,University of Perugia | And 2 more authors.
Knowledge and Management of Aquatic Ecosystems | Year: 2013

Squalius lucumonis (Bianco, 1983) is an endemic species restricted to three river basins in central Italy and listed as endangered according to IUCN Red List. The aim of this research was to increase the information on ecological preferences of this species and to focus on its differences with S. squalus (Bonaparte, 1837). Data collected in 86 different watercourses throughout Tiber River basin were analysed in the research. For each of the 368 river sectors examined, the main environmental parameters and the fish community were considered. The information were analysed by means of the Canonical Correspondence Analysis (CCA) while the differences in ecological traits between S. lucumonis and S. squalus were compared by ANOVA. The results of the study showed significant differences in the ecological preferences of the two species: the S. lucumonis showed predilection for smaller watercourses characterised by a lower number of species and a higher degree of integrity of fish community than S. squalus This information allowed to increase the basic knowledge on population biology and ecology of S. lucumonis that could be very useful for the management and conservation of this Italian endemic species. © ONEMA, 2013. Source


La Porta G.,University of Perugia | Angeli V.,University of Perugia | Bicchi A.,University of Perugia | Carosi A.,Provincia di Terni | And 3 more authors.
Journal of Applied Ichthyology | Year: 2010

The composition of fish populations in lake Piediluco has undergone significant changes in recent years, mainly as a result of environmental deterioration due to the eutrophication of its waters and the introduction of some alien species. Lake Piediluco is a natural, regulated lake, which has been used for the production of hydroelectric power since 1908. Over the years, the trophic status of the lake has been profoundly modified: until 1980 it was mesotrophic; by 1989 it had become eutrophic, and now it is deemed to be hyper-eutrophic. The aim of this research was to analyze variations in the composition of fish populations in relation to the trophic evolution of the lake and the introduction of alien species. The data on fish populations were gathered during four monitoring campaigns carried out in 1988, 1996, 1999 and 2004. To estimate the abundance of the various species, catches were standardized in terms of catch per unit effort (CPUE). The results of the research reveal that the increase of the trophic status of the lake has been accompanied by a qualitative and quantitative change in the composition and structure of the fish community, which is being increasingly dominated by omnivorous cyprinids, such as Scardinius erythrophthalmus and the alien Rutilus aula. This is taking place at the expense of species that are ecologically less resilient and commercially more interesting, supported by provincial management policies as annual repopulation programs and deployment of artificial spawning substrates. Moreover, in more recent years the presence of some new alien species has been recorded, such as Rutilus rutilus and Gymnocephalus cernuus. These species, which were not previously found, pose a further threat to commercial fishing in the lake. © 2010 Blackwell Verlag, Berlin. Source

Discover hidden collaborations