Stranding of marine megafauna in Moroccan waters: Species diversity, spatio-temporal distribution and main threats

We report the initial study on marine megafauna strandings in Moroccan waters (Atlantic and Mediterranean), conducted over a 10 year of study period from 2014 to 2023. Altogether, 524 marine megafauna strandings were documented, encompassing 9 families and 24 species. Cetaceans and sea turtles constitute 85.5 % (n = 448) and 14.5 % (n = 76) of the total stranded individuals, respectively. Of the 24 species identified stranded, seven species were classified as Endangered by the IUCN. The number of strandings events raised significantly between 2014 and 2023 and more rapidly between 2020 and 2023, which is probably due to growing anthropogenic activities and observation efforts in Moroccan waters. Specifically, Atlantic waters host the highest taxonomic diversity of marine megafauna (17 species of cetaceans and 2 species of sea turtles) compared to the Mediterranean (10 species of cetaceans and 2 species of sea turtles). Delphinus delphis (n = 151, 28.8 %), Stenella coeruleoalba (n = 60, 11.5 %), Balaenoptera acutorostrata (n = 52, 9.9 %) and Globicephala melas (n = 5) were the most frequently stranded cetacean species. For sea turtles, the most frequently recorded species was Caretta caretta (n = 52, 9.9 %) followed by Dermochelys coriacea (n = 24, 4.6 %). Strandings were observed throughout the year in Moroccan waters, but peaked in summer (June-August, n = 153, 29.2 %). The majority of stranding were associated to anthropogenic interactions. Among these instances, the bycatch was the primary factor in 257 occurrences of stranding. Our results contributed to a better understanding of marine megafauna communities in both Moroccan coasts, which are essential for improving research, management and conservation of marine turtles and cetaceans.