A novel approach for Mediterranean monk seal conservation: an artificial ledge in a marine cave

Abstract

The Mediterranean monk seal Monachus monachus, categorized as Endangered on the IUCN Red List, comprises 600–700 individuals in the eastern Mediterranean Sea and eastern Atlantic Ocean. Habitat degradation is a severe threat to the species. In 2016 and 2017, coastline surveys were conducted in Gökova Bay, south-west Turkey, to identify suitable monk seal habitat. A significant factor hindering recovery of the monk seal population of this Turkish coast and the nearby Greek islands is the limited number of marine caves suitable for resting and/or pupping. We identified four caves as possible monk seal resting and pupping caves. An additional cave with all essential features for seal usage except a ledge was also identified. An artificial ledge was built in this cave in July 2019 and seal usage was monitored by camera trap until September 2020. A total of 405 camera-trap events were analysed to examine presence of any monk seals on the ledge, and to understand the purpose (resting and/or pupping), frequency of use, sex and age group of any individuals using the cave. One juvenile used the cave four times for resting (420 minutes in total), predominantly nocturnally. This is the first construction of a dry ledge in a cave of this kind for monk seals. The camera recordings suggest this approach could provide habitat for this species in areas where there is insufficient dry protected area on land.

Developing artificial nest boxes for a large aquatic mammal

“…Field tests on nest boxes are being carried out with the aim of recovering the breeding habitat sites of Baltic ringed seals in the Archipelago Sea of Finland that are being lost due to climate change (Loisa O, 2022, personal communication). In addition, the first artificial ledge has been provided for Mediterranean monk seals in Gökova Bay, south‐west Turkey (Saydam, Güçlüsoy & Kızılkaya, 2022).…”

Revealing the Mediterranean Monk Seal (Monachus monachus)’s Cave Preference in Gökova Bay on the Southwest Coast of Türkiye

“…In light of local knowledge, cave research expeditions were then completed along most of Gökova Bay's 322 km coastline (Figure 1). The aim was to identify marine caves suitable for monk seal use as part of the Mediterranean Monk Seal Monitoring Program conducted by the Mediterranean Conservation Society (MCS) between 2016 and 2017 [24].…”

“…The team identified five potential monk seal caves (C1-C5) with surface entrances, including the cave with an artificially implemented dry ledge [24], and installed camera traps with PIR-based motion detectors. One to three camera traps were set up inside depending on the cave's size and the number of suitable dry areas for monk seal use.…”

“…The cause of death was unknown since a necropsy could not be performed due to advanced decay (Figure 6). For the cave with a manually implemented artificial dry ledge (C5), a juvenile used it for resting initially in 2020 [24], after which we recorded two other seals using the cave in October 2021. Given the impact of sea level rise that could be caused by climate change in the future [2], the implementation of the artificial dry platform as an alternative habitat for the Mediterranean monk seal is thought to offer the species potentially important support in pupping and resting.…”

Putting communities at the heart of marine conservation

“…This work has resulted in a 75% reduction in the poaching of nesting females, and has positioned Maio Island as a globally important refuge for the Vulnerable loggerhead sea turtle (Patino-Martinez et al, 2022) and one of the largest nesting colonies (Patino-Martinez et al, 2023). Finally, in Turkey, local NGO Akdeniz Koruma Derneği has developed community-based management for six no-take zones in the Gökova Bay marine protected area, resulting in a significant increase in fish biomass, and has successfully trialled a novel conservation approach for the Endangered Mediterranean monk seal, constructing an artificial ledge in a cave to provide critical pupping and resting habitat (Saydam et al, 2023).…”