Spatio-temporal trends in cetacean strandings and response in the southwestern Indian Ocean region - 2000 to 2020
S. Pl?n, S. Norman, P.A. Adam, N. Andrianarivelo, S. Bachoo, G. Braulik, T. Collins, V. Estrade, O. Griffiths, G. Inteca, N. Khan, S. Marinesque, E. Mederic, M. Mwang?ombe, J. Olbers, L. Ramoelintsalama, K. Reeve-Arnold, D. Rocha, A.D. Gullan,
The southwestern Indian Ocean (SWIO) is a region of global importance for marine mammal biodiversity, yet our understanding of most of the species and populations found there is still rudimentary. The Indian Ocean Network for Cetacean Research (IndoCet) was formed in 2014 and is dedicated to the research of all cetacean species across the SWIO. Since 2019, the importance of a regional network for coordinated response to stranding events as well as training and capacity building in the SWIO region, has been recognized. The present analysis represents a first look at stranding data collected by various members and collaborators within the IndoCet network, covering over 14,815km of coastline belonging to nine countries. Cetacean stranding patterns and finer scale spatial and spatio-temporal patterns were characterized. Between 2000-2020, there were 398 stranding events, representing 1,259 individual animals, 17 genera, and 27 species, comprising six families: four balaenopterids, one balaenid, one physeterid, two kogiids, six ziphiids and 14 delphinids. Seven mass strandings were recorded: two were composed of three to 20 individuals and five were composed of >20 individuals. Spatial analysis of stranding events indicated local spatio-temporal clusters were present in all countries/territories except for the Comoros; however, the only significant cluster was detected on the southwest coast of Mauritius just west of the village of Souillac. The SWIO region is predominantly composed of relatively poor range countries, yet imminent Blue/Ocean economy developments are prevalent throughout the region. This study highlights the importance of establishing baselines upon which any future potential impact from anthropogenic developments in the region can be measured.