1,720,962 research outputs found
Un metodo per l'acquisizione dei dati oceanografici durante l'attività di pesca a strascico = A method for collecting oceanographic data during the bottom trawling
No full textPreliminary data on the trophic interactions between Scyliorhinus canicula (Scyliorhinidae) and Raja clavata (Rajidae) in the Central-Western Mediterranean
No full textPreliminary data on the diet and trophic competition between Scyliorhinus canicula and Raja clavata, caught in the seas surrounding Sardinia (central-western Mediterranean),during trawl surveys carried out from 2005 to 2008 are given. The low values of Levin and Shannon-Weaver indexes showed that these two species are specialized predators. The ontogenetic analysis of the diet showed different predatory patterns
Geographical and bathymetrical distribution of red shrimps in Sardinian waters related to environmental conditions
No full textRed shrimps Aristaeomorpha foliacea and Aristeus antennatus are one of the most important and exploited resource in the western
Mediterranean. The aim of this work is to evaluate the geographical and bathymetrical distribution of the two species in Sardinian seas
and to identify a possible relationship with environmental conditions. We calculated the ratio between the two species and we
compared ratio values with hydrological data (temperature and salinity) to establish how water masses properties influence species
distribution. Our results indicate that A. antennatus prefers colder and less salty waters while A. foliacea prefers both higher
temperature and salinity
Assemblages in a submarine canyon: influence of depth and time
No full textIn this work we have studied the assemblages from Quirra canyon (Sardinia). We analysed data from 25 trawl samples from the canyon, made at different times and depth. A total of 71 demersal species (38 teleosts, 5 cartilaginous fishes, 13 molluscs and 15 crustaceans) were examined. We found four groups using cluster analysis; each group is characterised by a certain depth or time. In particular we have shown that the time of the day appears to have a role in the movement of shrimps and other species. This phenomenon seems to be linked to trophic need and by the consequent different food availability into the Canyo
Definizione delle coorti d’età in piccoli campioni attraverso l’analisi multivariata: l’esempio dello zerro
No full textMultivariate analysis allowed to determine the minimum sample size and the variable for a cohort deconvolution with reduced number of individuals. The analysis have been carried out on biometric data of Spicara smaris. We found that at least 50 records for the picarel are need. The most suitable variables are total and anal length
The exploitation of red mullet (Mullus barbatus) in the southern Sardinian Sea (Central-Western Mediterranean): protection of the nursery areas and implications for management
No full textDemersal assemblages in two trawl fishing lanes located on the Baronie seamount (Central Western Mediterranean)
No full textThis work focuses on the species associations of the Baronie Seamount (north-eastern Sardinia, Italy), according to variations in depth and time of day. The aim was to highlight the potential vertical movements of the species and to compare these results to existing data from a submarine canyon. Twenty-two samples were taken at different depths and times along two trawl lines over the seamount. A total of 94 species were caught; among these, 48 bony fish, 9 cartilaginous fish, 13 molluscs and 24 crustaceans were selected for analysis. Cluster analysis showed 3 groups in which both depth and time of day play an important role in grouping. Nine species showed some daily and nocturnal movement, probably linked to trophic requirements. The daily movements according to size and sex of the shrimps Aristaeomorpha foliacea and Aristeus antennatus were also studied. For these two populations, the analysis showed an uneven distribution and the did l cycle appears to involve only the females. These species seem to adapt their life cycle to the geomorphology of the sea bottom. The diurnal movements from the base of the seamount to the edge of the continental shelf increase the range of the species distribution. In fact, the seamount, due to its geomorphological conformation, offers these species the opportunity to very quickly span a considerable range of depths. These movements are known to occur in the continental shelf and slope, but in the seamount they are broadened and can be studied more easily
The red coral resource in Sardinian seas: a multidisciplinary survey on Corallium rubrum populations
No full textThe red coral resource in Sardinian seas: a multidisciplinary survey on Corallium rubrum populations - A multidisciplinary
study is presented in order to give an historical and actual picture of the status of Corallium rubrum in Sardinian seas. The
review of historical data (1978-2005) shows that no variation occurred in mean yields/boat and suggests that yield of red coral in
Sardinian seas has not decreased with time. A picture of the spatial distribution of red coral in deep waters of Sardinian seas (below 80
meters) is given, for the first time, through analyses of ROV surveys and samplings of commercial colonies. These findings suggest that
the populations have dimensions able to ensure the reproductive output needed for their survival. Furthermore, genetic analyses show
strong heterogeneity between Sardinian samples and corals from other western Mediterranean localities and even high differentiation
among Sardinian samples, distant from hundreds to less than 1 km. In conclusion, the strong genetic structuring confirms the need for
management plans and conservation programs to be locally defined. Moreover, population structure data suggest that the harvesting
effort should not be increased
- …
