The Rough-Toothed Dolphin, Steno bredanensis, in the Eastern Mediterranean Sea: A Relict Population?

Insights into the distribution and ingestion of prey-like plastic fishing lures in Mediterranean rough-toothed dolphins

Rough-toothed dolphins (Steno bredanensis) form an isolated subpopulation in the Mediterranean Sea that resides only in the eastern basin. Due to the paucity of records, the conservation threats these dolphins face and their ecology and distribution are poorly understood. While most observations indicate that individuals are found in two isolated clusters in the eastern basin, we hereby present five observations -three visual, one acoustic and one stranding- that possibly extend the range of this subpopulation to the entire offshore waters of the eastern basin. The stomach content remains of the stranded individual revealed a diet based on epipelagic squids and octopods. The stranded dolphin had also consumed seven plastic bags and nine squid-like plastic fishing lures, which had caused a complete gastric blockage and probably led to the stranding. High pollution loads from macroplastics in the Mediterranean Sea may evolve into a new potential threat for this subpopulation.

Cetacean Strandings and Museum Collections: A Focus on Sicily Island Crossroads for Mediterranean Species

The study examined the extent of the cetacean strandings in Italy, with a particular focus on Sicily Island. The paper aimed to contribute to the description of a pattern that contemplates the “regular and rare” cetacean species passage along the Sicilian coast. The estimate of marine cetacean strandings was extrapolated from the National Strandings Data Bank (BDS—Banca Dati Spiaggiamenti) and evaluated according to a subdivision in three coastal subregions: the Tyrrhenian sub-basin (northern Sicilian coast), the Ionian sub-basin (eastern Sicilian coast), and the Channel of Sicily (southern Sicilian coast). Along the Italian coast, more than 4880 stranding events have been counted in the period 1990–2019. Most of these were recorded in five Italian regions: Apulia, Sicily, Sardinia, Tuscany, and Calabria. Approximately 15% of the recorded strandings in Italy occurred on the Sicilian coast. In Sicily Island, 725 stranded cetaceans were recorded in 709 stranding events, resulting in approximately 20 carcasses every year; the total number of specimens identified to species level was 539. The distribution along the Sicilian coast was the following: 312 recorded in the Tyrrhenian sub-basin, 193 in the Ionian sub-basin, and 220 in the Channel of Sicily. Stenella coeruleoalba was the species that can be considered as the stable record along the time-lapse investigated, and some rare species have been recorded as well. The role of Sicily Island as a sentinel territory of the cetacean distribution for the central Mediterranean Sea and as a region receiving a marine resource suitable for the scientific research and cetological museum collections is discussed herein.