Sandbar shark aggregation in the central Mediterranean Sea and potential effects of tourism

Abstract

An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south‐western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience. Despite the ecological and socio‐economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species. Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects that boating and diving activities may have on sandbar sharks during two different periods within the tourism season (July and September 2019). Overall, 241 sandbar shark sightings (with up to five individuals together) were recorded in July, whereas there were only six sightings in September. The average MaxN was 1.18 hr−1 (±0.21 hr−1 SE) and 0.22 hr−1 (±0.10 hr−1 SE) individuals in July and September respectively. Higher frequentation levels of divers and boats significantly reduced the number of shark sightings at the aggregation site. This study emphasizes the need for further investigations on Mediterranean shark aggregations and the implementation of specific conservation measures, such as an increase of protection level in Lampione and better enforcement, aside from strategies that promote sustainable tourism, including restrictions on the number of boats and divers’ visits per day. In the meantime, a precautionary approach aimed at regulating the interactions between tourists and sharks should be implemented through the application of a self‐regulatory code of conduct for divers when sharks aggregate around the island.

The use of fishers’ Local Ecological Knowledge to reconstruct fish behavioural traits and fishers’ perception of conservation relevance of elasmobranchs in the Mediterranean Sea

“…Carcharhinus plumbeus has been seen aggregating in Boncuk Cove (Turkey) (Filiz et al, 2019) and forming seasonal aggregations in Israel (Barash et al, 2018) and Lampione Island (Sicily) (Cattano et al, 2021). In addition, GSAs 10 and 19 were recognised as previously unreported aggregating areas of C. plumbeus by LEK in the present study.…”

Preliminary insights of a mixed-species shark aggregation: a case study of two carcharhinids from the Mediterranean Sea

“…The power station of Hadera is regularly visited by swimmers, snorkelers, scuba divers, kayaks, small boats, and jetskis. In other reports, these sharks have been shown to flee from of divers and swimmers (Shamir et al 2019, Cattano et al, 2021. It is not known whether such perturbations can be more detrimental and affect shark fitness.…”

Small-scale fisheries catch more threatened elasmobranchs inside partially protected areas than in unprotected areas

“…In this regard, based on evidence from the literature and previous management success stories we propose four recommendations. First, fill the critical scientific data gap by finding ways to support data collection on abundance, biomass, size, spatial distribution, and habitat association of shark and batoid species, as well as life-history characteristics 75 , inside and outside MPAs, coupling fishery-dependent (e.g., landings assessment, as used in the present study) and fishery-independent approaches (e.g., deploying Baited Remoted Underwater Videos 5 , 76 – 78 ). Second, focus on fishing‐effort controls, including gear or temporal restrictions, and on the use of shark dissuasive devices 79 .…”