Search

Between 2007 and 2022, 112 specimens of newborn and young pelagic sharks were recorded in the waters of Tuscany Region, in the South Ligurian–North Tyrrhenian Seas (north-western Mediterranean basin). The sharks belonged to the Carcharhinus plumbeus (n = 14), Prionace glauca (n = 66), Isurus oxyrinchus (n = 16), Mobula mobular (n = 5) Alopias vulpinus (n = 7) and Hexanchus griseus (n = 4) species. Each animal was correctly identified thanks to the photographs or videos collected. All specimens were incidentally captured with set nets in inshore shallow waters, except bluntnose six-gill sharks, which were bycatch of deep-water bottom-trawl fishery. Body mass, sex, total length and biometric measurements were recorded in 34 baby sharks following the Mediterranean Large Elasmobranches Monitoring (MEDLEM) protocol. The presence of very evident and often non-healed umbilical scar confirmed that some of the sample specimens were newborn. Further confirmation came from the comparison between the total length observed and the size at birth known for the sampled species as reported in the literature. Some baby sharks were preserved in the Museums of Natural History of Pisa and Florence University collections. The importance of the coastal area studied as a possible shark nursery is discussed.

In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and one species of Peristediidae) in the northern Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas and ecoregions, with the highest relative biomass (BIy) being found in Malta, eastern Corsica, the Balearic Islands and the eastern Ionian Sea. The lowest gurnards BIy were observed in the highly exploited areas of the western Mediterranean and the Adriatic Sea, where the largest number of species with a negative linear trend in BIy was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus) as compared with the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provide for the first time an overview of the spatiotemporal trend in the abundance of gurnards over the wide spatial scale of the northern Mediterranean Sea, also suggesting the possible use of these species as indicators for monitoring the impact of fishing pressure on demersal fish assemblages.

Cetaceans can be considered good natural samplers of biodiversity due to the different hunting strategies they adopt. In this study, the stomach contents of 28 Tursiops truncatus (15 females and 13 males), stranded along Tuscany coasts, NW Mediterranean, between 2008 and 2021, were analyzed. The prey items were identified at the lowest taxonomic level possible, and assessed in terms of abundance, weight, and frequency of occurrence. The index of relative importance (IRI) was also computed. Overall, 2201 bony fishes and 406 cephalopods were identified. The trophic spectrum resulted in high diversity (69 taxa) and the prey species, 53 fishes and 16 cephalopods, live at different levels of the water column. Predation was mainly based on European hake, Merluccius merluccius (%IRI 26.9), and conger eel, Conger conger (%IRI 25.1). The abundant presence of nocturnal species, such as Conger and Ophidion, indicates the nocturnal hunting activity of the bottlenose dolphin. Furthermore, evidence is presented of the dolphins’ ability to capture fish at night, taking advantage of the sound produced by these fish to locate them. Diet did not show any statistical differences among sexes, except that females preyed upon a significantly higher quantity of octopods than males.

The distribution and biological features of anglerfish (Lophius piscatorius and L. budegassa) in the Mediterranean Sea were analysed from trawl surveys data (MEDITS project, years 1994-1999). The above-mentioned species were widely distributed in the Mediterranean, but differences in abundance were found according to geographic sectors and depths. Most of the collected specimens belonged to the first length cohorts and length distributions also differed at macro-area levels. Mean sizes at female sexual maturity were estimated at 68.5 cm and 66.2 cm total length, respectively for L. piscatorius and L. budegassa.