Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrate

Abstract

Establishing how wildlife viewing pressure is distributed across individual animals within a population can inform the management of this activity, and ensure targeted individuals or groups are sufficiently protected. Here, we used social media data to quantify whether tourism pressure varies in a loggerhead sea turtle (Caretta caretta) population and elucidate potential implications. Laganas Bay (Zakynthos, Greece) supports both breeding (migratory, and hence transient) and foraging (resident) turtles, with turtle viewing representing a major component of the tourism industry. Social media entries spanning two seasons (April to November, 2018 and 2019) were evaluated, and turtles were identified via photo-identification. For both years, 1684 and 2105 entries of 139 and 122 unique turtles were obtained from viewings, respectively (boats and underwater combined). However, while residents represented less than one-third of uniquely identified turtles, they represented 81.9% and 87.9% of all entries. Even when the seasonal breeding population was present (May to July), residents represented more than 60% entries. Of note, the same small number of resident turtles (<10), mostly males, were consistently viewed in both years; however, different individuals were targeted by boats versus underwater. Thus, turtles appear to use and remain in the area despite high viewing intensity, possibly indicating low disturbance. However, photo-identification records revealed a high risk of propeller and boat strike to residents (30%) leading to trauma and mortality. To reduce this threat and ease viewing pressure, we recommend the compulsory use of propeller guards for all boats and the creation of temporary "refuge" zones for resident animals at viewing hotspots, with these suggestions likely being relevant for other wildlife with similar population dynamics. In conclusion, social media represents a useful tool for monitoring individuals at a population scale, evaluating the pressure under which they are placed, and providing sufficient data to refine wildlife viewing guidelines and/or zoning.

COVID‐19 disruption reveals mass‐tourism pressure on nearshore sea turtle distributions and access to optimal breeding habitat

“…Creel et al, 2005; Heithaus et al, 2012), turtles must make trade‐offs between accessing optimal resources and evading humans, supporting the risk allocation hypothesis (Lima & Bednekoff, 1999). This finding reinforces the importance of obtaining an evidence base of animal behaviour when human activities are absent, to identify such trade‐offs and quantify potential costs incurred (Papafitsoros et al, 2020; Rutz et al, 2020).…”

“…Thus, a refuge zone would only be partially effective across any given season (i.e. when conditions coincide with preferred turtle use); yet, it might also form an effective public awareness/education tool with associated economic benefits (Gregr et al, 2020; Papafitsoros et al, 2020; Togridou et al, 2006b). Studies using animal‐borne cameras have also demonstrated that sea turtles scope out potential nesting habitat during the daytime (Fuller et al, 2009).…”

“…Zakynthos Island in Greece (Figure 1; 37°43′ N, 20°52′ E) supports an important breeding rookery for loggerhead sea turtles ( Caretta caretta ) in the Mediterranean Sea (Almpanidou et al, 2016; Casale et al, 2018; Casale & Margaritoulis, 2010), in parallel to being a major tourism destination, attracting over 850,000 visitors each summer (typically May to October) (Papafitsoros et al, 2020). The National Marine Park of Zakynthos (NMPZ) was established in 1999 (Figure 1a; Margaritoulis, 2005) to protect the breeding habitat of loggerhead sea turtles frequenting Laganas Bay, located on the southern part of the island.…”

“…Recreation and wildlife watching activities in coastal areas have been widely documented to negatively impact marine mammals, turtles and elasmobranches (e.g. Casale et al, 2020; Christiansen & Lusseau, 2014; Semeniuk et al, 2009); yet, such studies typically target individuals or small groups of animals in organized viewing settings, failing to capture potential responses at population levels (Christiansen & Lusseau, 2014; Larson et al, 2016; Papafitsoros et al, 2020). For example, while sea turtles are widely studied marine vertebrates globally (Hays & Hawkes, 2018), our understanding of their movement and behaviour is constrained by available technologies (Kays et al, 2015; Koh & Wich, 2012; Wilmers et al, 2015).…”

“…However, in addition to sea temperature, the number of people visiting Zakynthos also sharply rises over the same period during summer (Arianoutsou, 1988; Mazaris et al, 2009; Papafitsoros et al, 2020), potentially increasing pressure on turtles in the marine area through more encounters and greater noise pollution. Human pressure has been inferred through monitoring the responses of individual turtles to recreational activities at Zakynthos (Papafitsoros et al, 2020; Schofield et al, 2015) and other sites (Casale et al, 2020; Samuel et al, 2005). However, obtaining clear‐cut evidence that human activities alter the in‐water distribution of sea turtles at the population level is challenging (Rees et al, 2016; Schofield et al, 2020).…”