TY - JOUR
T1 - Spatiotemporal variations in reef manta ray (Mobula alfredi) residency at a remote meso-scale habitat and its importance in future spatial planning
AU - Harris, Joanna L.
AU - Williamson, Benjamin J.
AU - Stevens, Guy M.W.
AU - Hosegood, Phil
AU - Robinson, E
AU - Embling, Clare B.
N1 - Publisher Copyright:
© 2024 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd.
PY - 2024/2/1
Y1 - 2024/2/1
N2 - The Chagos Archipelago's vast no-take marine protected area (MPA, 640,000 km2) provides refuge for elasmobranchs facing unsustainable depletion by fisheries. Nonetheless, illegal, unreported and unregulated (IUU) fishing poses a substantial threat, and potential future changes to the use of the MPA could render elasmobranchs increasingly vulnerable to exploitation, putting geographically isolated populations, such as reef manta rays (Mobula alfredi) at risk of local extinction. Therefore, the species' long-term movements and habitat use must be identified to help prioritize current enforcement activity and inform future spatial planning.
Passive acoustic telemetry and modelled environmental data were used to investigate variations in 42 tagged M. alfredi utilization of a meso-scale aggregation hotspot, Egmont Atoll, between 2019 and 2022.
Mobula alfredi displayed the highest levels of residency ever reported (77%), with prolonged absences (>2 months) limited to seven individuals. Egmont atoll was used year-round, with activity peaks during the southeast monsoon (April – November), particularly at sites on the southwest, while sites on the northwest were predominately frequented in the northwest monsoon (December–March). Tags were most likely to be detected when the Indian Ocean Dipole (IOD) was in a positive phase with a greater mixed layer depth, associated with a depression of chlorophyll α levels in the Indian Ocean. Thus, M. alfredi may be particularly reliant on Egmont Atoll, where they are predominantly observed feeding, when prey resources are limited elsewhere.
In a region where the threat of fisheries is of increasing concern, the identification of crucial M. alfredi habitats is essential for conservation management planning. Given the significant role of Egmont Atoll for the local population, regular IUU enforcement patrols are crucial, particularly during the southeast monsoon. Any future changes to the MPA should prioritize preserving and actively enforcing no-take regulations at Egmont Atoll.
AB - The Chagos Archipelago's vast no-take marine protected area (MPA, 640,000 km2) provides refuge for elasmobranchs facing unsustainable depletion by fisheries. Nonetheless, illegal, unreported and unregulated (IUU) fishing poses a substantial threat, and potential future changes to the use of the MPA could render elasmobranchs increasingly vulnerable to exploitation, putting geographically isolated populations, such as reef manta rays (Mobula alfredi) at risk of local extinction. Therefore, the species' long-term movements and habitat use must be identified to help prioritize current enforcement activity and inform future spatial planning.
Passive acoustic telemetry and modelled environmental data were used to investigate variations in 42 tagged M. alfredi utilization of a meso-scale aggregation hotspot, Egmont Atoll, between 2019 and 2022.
Mobula alfredi displayed the highest levels of residency ever reported (77%), with prolonged absences (>2 months) limited to seven individuals. Egmont atoll was used year-round, with activity peaks during the southeast monsoon (April – November), particularly at sites on the southwest, while sites on the northwest were predominately frequented in the northwest monsoon (December–March). Tags were most likely to be detected when the Indian Ocean Dipole (IOD) was in a positive phase with a greater mixed layer depth, associated with a depression of chlorophyll α levels in the Indian Ocean. Thus, M. alfredi may be particularly reliant on Egmont Atoll, where they are predominantly observed feeding, when prey resources are limited elsewhere.
In a region where the threat of fisheries is of increasing concern, the identification of crucial M. alfredi habitats is essential for conservation management planning. Given the significant role of Egmont Atoll for the local population, regular IUU enforcement patrols are crucial, particularly during the southeast monsoon. Any future changes to the MPA should prioritize preserving and actively enforcing no-take regulations at Egmont Atoll.
KW - IUU fishing
KW - Mobula alfredi
KW - acoustic telemetry
KW - elasmobranch
KW - marine protected area
KW - residency
UR - http://www.scopus.com/inward/record.url?scp=85184239015&partnerID=8YFLogxK
U2 - 10.1002/aqc.4089
DO - 10.1002/aqc.4089
M3 - Article
SN - 1052-7613
VL - 34
JO - Aquatic Conservation: Marine and Freshwater Ecosystems
JF - Aquatic Conservation: Marine and Freshwater Ecosystems
IS - 2
M1 - e4089
ER -