scholarly journals Biological Aspects of Juveniles of the Common Stingray, Dasyatis pastinaca (Linnaeus, 1758) (Elasmobranchii, Dasyatidae), from the Central Mediterranean Sea

2020 ◽  
Vol 8 (4) ◽  
pp. 269
Author(s):  
Francesco Tiralongo ◽  
Giuseppina Messina ◽  
Bianca Maria Lombardo

Data on the biology of Dasyatis pastinaca are absent from the Ionian Sea and only a few studies were conducted in the Mediterranean Sea. Some biological and ecological aspects of D. pastinaca were investigated between November 2019 and February 2020 in the central Mediterranean Sea. In particular, we investigated several morphologic, population and ecological aspects of the species. The analysis of the stomach contents showed that D. pastinaca is a generalist carnivorous, mainly feeding on small crustaceans and polychaetes. The Levin’s index value (Bi) was 0.85. The sex ratio showed no significant differences from 1:1 ratio. Females were larger than males, but no statistical differences were found in disc width-weight and total length-disc width relationships between sexes. Most of the specimens caught were juveniles and inhabit shallow sandy bottoms.

2019 ◽  
Vol 60 (2) ◽  
pp. 199-204
Author(s):  
Francesco Tiralongo ◽  
Ioannis Giovos ◽  
Giuseppina Messina ◽  
Daniele Tibullo ◽  
Bianca Maria Lombardo

Two specimens of the common goby (Pomatoschistus microps) were observed in the estuarine environment of the River Asinaro (Sicily). These records represent the easternmost and southernmost observations of the species in the Mediterranean Sea, and the first confirmed record in the Ionian Sea (central Mediterranean Sea). We also provide notes about its habitat and current distribution in the Mediterranean Sea.


2004 ◽  
Vol 68 (S3) ◽  
pp. 117-127 ◽  
Author(s):  
Francisco Sardà ◽  
Gianfranco D'Onghia ◽  
Chrissi Yianna Politou ◽  
Joan Baptista Company ◽  
Porzia Maiorano ◽  
...  

Author(s):  
Roberto Carlucci ◽  
Francesca Capezzuto ◽  
Giulia Cipriano ◽  
Gianfranco D’Onghia ◽  
Carmelo Fanizza ◽  
...  

AbstractThe exploitation of fishery resources acts as a driving force on cetaceans both directly, by determining their fishing mortality or injury as by-catch species, and indirectly, through the lowering the availability of their prey. This competitive overlap between fishing and cetaceans often results in inadequate solutions so that in some cases there have been cases of intentional cetacean culling to maximize fishing production. A modelling approach applied to investigate the ecological roles of cetaceans in the food web could prove more effective to integrate ecological and fishing aspects and to provide suggestions for management. The comparative analysis carried out in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) showed that fishing exploitation provides impacts on the investigated food web greater than those due to cetacean predation. Trawling was estimated to be the most negatively impacting fishing gear considering the mortality rates and consumption flows. On the other hand, the striped dolphin was the main impact on the food web due to its highest consumption flows. Analysis showed a negative and non-selective impact on the exploited species due to the fishing gears, while the odontocetes proved to select their prey species and provide a positive impact in the assemblage. In particular, while the fishing gears are primarily size selective, targeting mostly large and economically valuable fish, the odontocetes seem to follow a co-evolution process with their prey, developing a specialization in their resources, providing control of the meso-consumers and ensuring a trophic stability in the ecosystem.


Author(s):  
P. Carpentieri ◽  
F. Colloca ◽  
G. Ardizzone

We investigated daily ration, feeding rhythms and gastric evacuation rates of juvenile (<16 cm total length) European hake Merluccius merluccius, using stomach samples collected during four 24-hour trawl surveys carried out in 2001–2002 on the continental shelf-break (from 120 m to 160 m in depth) off the western coast of central Italy (central Mediterranean Sea). In each survey 8 hauls of 30 minutes were performed every three hours throughout the 24-hour period to cover the entire diel cycle. Diet of juvenile hake was mostly composed of the euphausiid Nyctiphanes couchii, showing a peak in stomach contents during early morning followed by a daytime decrease. Fullness index (%FI) was generally higher during sunrise when migratory activity ceased and juvenile hake return to the bottom after feeding. Concerning the hake abundance the highest density value was obtained in May during the recruitment period.Two independent daily ration estimates were produced. First, an empirical attempt to estimate the daily amount of food consumed was obtained by back-calculating the fresh weight of euphausiid prey ingested by juvenile hake. Estimated values ranged from 4.96–5.89% body wet weight (%BW). Second, the daily ration was computed applying the exponential gastric evacuation models proposed by Elliot & Persson (1978) and Eggers (1979). Daily ration values obtained using these consumption models produced a considerable (15–20%) underestimation of consumption rate for juvenile hake.


Author(s):  
Francesca Cornelia Santacesaria ◽  
Giulia Cipriano ◽  
Stefano Bellomo ◽  
Roberto Carlucci ◽  
Roberto Crugliano ◽  
...  

Author(s):  
Manuela Falautano ◽  
Luca Castriota ◽  
Maria Grazia Finoia ◽  
Franco Andaloro

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).


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