Sightings of risso’s dolphin (grampus griseus) off the Southern coast of Linosa island (South-Central Mediterranean Sea)

Abstract

Risso’s dolphin distribution, habitat preferences, and site fidelity in the Strait of Sicily are very little known. During three summer seasons of sea surveys, we sighted this species offshore Linosa island in groups of variable numbers of individuals (2-20 with an average of 9.7 ± 7.0 SD). Sightings were located in a small area showing medium depth (average 591 m) and bathymetric features that usually correspond with known habitat preferences of the species. A total of 32 individuals belonging to 4 age classes were photo-identified and 8 of them were re-sighted once over years. This work illustrates for the first time, the presence of the species in the studied area and the results seem to indicate a site fidelity over years.

Submarine canyons as key habitats to preserve Risso’s dolphin (Grampus griseus) populations in the northwestern Mediterranean Sea

“…The ER of Risso's dolphin in the study area obtained in this study is consistent with the results obtained in the West Mediterranean Basin (Goḿez de Segura et al, 2006;Laran et al, 2021) and Gulf of Taranto (Central-eastern Mediterranean Sea) (Carlucci et al, 2020) and higher than the ER from aerial surveys in a closer area (Goḿez de Segura et al, 2008;ACCOBAMS, 2021). However, the ER value was lower than in the Mediterranean Sea (Corrias et al, 2021).…”

“…Risso's dolphin, Grampus griseus (Cuvier, 1812), is a cosmopolitan cetacean species that occurs in temperate and tropical waters and that has a heterogeneous distribution in the Mediterranean Sea (Azzellino et al, 2008;Boisseau, 2010;Bearzi et al, 2011;Gaspari and Natoli, 2012;Azzellino et al, 2016). The species' area of occurrence in the Mediterranean includes the Alboran Sea (Cañadas et al, 2002;Cañadas et al, 2005;Gannier, 2005), the Ligurian Sea (Di Sciara et al, 1993;Gannier, 2005;Azzellino et al, 2008;Moulins et al, 2008;Azzellino and Lanfredi, 2015;Azzellino et al, 2016), the Sardinian-Balearic Basin (Goḿez de Segura et al, 2008;Arcangeli et al, 2018), Chicote et al, 2015 the Strait of Sicily (Corrias et al, 2021), the Tyrrhenian Sea (Raga and Pantoja et al, 2004;Arcangeli et al, 2012;Campana et al, 2015), the Adriatic Sea (UNEP MAP-RAC/SPA, 2014), and the Ionian (Frantzis and Herzing, 2002;Dimatteo et al, 2011;Carlucci et al, 2020;Menniti and Vella., 2022) and Aegean basins (Frantzis and Herzing, 2002). Very little is known about the waters of Levantine and North Africa (Kerem et al, 2012), although some efforts were done in 2018 in North Africa (ACCOBAMS, 2021).…”

The social behaviour of the common bottlenose dolphin Tursiops truncatus (Montagu, 1821) in the coastal waters of Lampedusa Island (Strait of Sicily, Italy)

“…This study analysed the social features of bottlenose dolphins inhabiting waters around Lampedusa Island, which is part of the Pelagian Archipelago and is located in the Strait of Sicily (south‐central Mediterranean Sea), an important area connecting the western and the eastern basins of the Mediterranean Sea. The Pelagian Archipelago is a hotspot for cetaceans, including both regular species such as the common bottlenose dolphin (Pulcini et al, 2014), Risso's dolphin Grampus griseus (Corrias, Filiciotto & Giardina, 2021), striped dolphin Stenella coeruleoalba , common dolphin Delphinus delphis (Pace et al, 2015), and, seasonally, the fin whale Balaenoptera physalus (Canese et al, 2006; Panigada et al, 2017). This hotspot is linked to different topographic features, such as islands, seamounts, and canyons, which induce physical processes (i.e., upwelling and convergence zones) that influence food availability (Genin, 2004).…”