Conservation of reef manta rays (Manta alfredi) in a UNESCO World Heritage Site: Large-scale island development or sustainable tourism?

Abstract

A large reef manta ray (Manta alfredi) aggregation has been observed off the north Sudanese Red Sea coast since the 1950s. Sightings have been predominantly within the boundaries of a marine protected area (MPA), which was designated a UNESCO World Heritage Site in July 2016. Contrasting economic development trajectories have been proposed for the area (small-scale ecotourism and large-scale island development). To examine space-use, Wildlife Computers® SPOT 5 tags were secured to three manta rays. A two-state switching Bayesian state space model (BSSM), that allowed movement parameters to switch between resident and travelling, was fit to the recorded locations, and 50% and 95% kernel utilization distributions (KUD) home ranges calculated. A total of 682 BSSM locations were recorded between 30 October 2012 and 6 November 2013. Of these, 98.5% fell within the MPA boundaries; 99.5% for manta 1, 91.5% for manta 2, and 100% for manta 3. The BSSM identified that all three mantas were resident during 99% of transmissions, with 50% and 95% KUD home ranges falling mainly within the MPA boundaries. For all three mantas combined (88.4%), and all individuals (manta 1–92.4%, manta 2–64.9%, manta 3–91.9%), the majority of locations occurred within 15 km of the proposed large-scale island development. Results indicated that the MPA boundaries are spatially appropriate for manta rays in the region, however, a close association to the proposed large-scale development highlights the potential threat of disruption. Conversely, the focused nature of spatial use highlights the potential for reliable ecotourism opportunities.

The geographic distribution of reef and oceanic manta rays (Mobula alfredi and Mobula birostris) in Australian coastal waters

“…It is well-established that M. alfredi exhibits strong migratory behaviour and movements of up to 500 km are not uncommon (Couturier et al, 2011;Germanov & Marshall, 2014;Jaine et al, 2014), with few confirmed dispersals in Australia up to 1150 km . Individual rays have demonstrated affinity for particular sites and regions (Braun et al, 2015;Couturier et al, 2014;Kessel et al, 2017;Marshall et al, 2011), although most photo-ID and tagging studies have focused on populations separated by large distances and/or by regions of deep water (Deakos et al, 2011).…”

The geographic distribution of reef and oceanic manta rays in the south-east Indian and south-west Pacific Oceans

“…It is well-established that M. alfredi exhibits strong migratory behaviour, with movements of up to 500 km not uncommon (Couturier et al 2011, Germanov and Marshall 2014, Jaine et al 2014) and recently movements of at least 1150 km have been demonstrated (Armstrong et al 2019). Photo-identification and tagging studies show that individual rays have an affinity for particular sites and regions (Braun et al 2015, Couturier et al 2014, Kessel et al 2017, Marshall et al 2011). However, most studies have focused on populations separated by large distances and/or by regions of deep water (Deakos et al 2011).…”

Distribution and diversity of fish species exposed to artisanal fishery along the Sudanese Red Sea coast

“…With its semi-enclosed location between the African continent and the Arabian peninsula the waters of the Red Sea are warmer and more saline than many other marine tropical ecosystems [1]. The Red Sea is host to a uniquely rich marine biodiversity and high prevalence of endemic species [2,3,4]. While the northern reef areas of Egypt and the Gulf of Aqaba/ Eilat have been extensively investigated [1, 5], the Red Sea proper is generally poorly studied, and only rudimentary studies from decades back have focused on commercial fisheries [6].…”

“…Most studies from the region are over 50 years old and have primarily focused on single reef study sites such as the Costeau Conshelf habitation experiment at Sha’ab Rumi in 1963 [9]. More recently, the Dungonab Bay area north of Port Sudan was studied and deemed to be of global significance and has subsequently been included in the UNESCO list of world heritage sites since 2016 along with the Sanganeb atoll as the “Dungonab Bay – Mukkawar Island Marine National Park” and the “Sanganeb Marine National Park” [4]. Historically, specimen collectors and early natural scientists have described the marine fauna [1,10,11], but thus far there have been no large-scale studies systematically covering the coastal fish assemblages (but see Kattan et al [7]).…”

“…The 2008 Equipe Costeau expedition was the most comprehensive study to date, but has limited value in terms of describing the marine fishery resources as it only covered a small part of the coast, focusing on local biodiversity rather than abundance [4, 12]. Their teams applied underwater visual census (UVC) methodology to survey the reef fish assemblages and collect benthic data [12].…”