New occurrence of cetacean stranded on the Algerian West Coast and Associated Threats: (2016-2020)

Abstract

The cetacean populations of the Algerian west coast are monitored in terms of relative abundance, demographic and ecological parameters, and death causes by Environmental Monitoring Network Laboratory team (EMNL) throughout the Algerian west coast. A survey of cetaceans stranded along the Algerian west coast (2016-2020) allowed us to record a total number of 52 stranding events, know the appearance frequency of different species, specify the spatio-temporal distribution, and determine some causes of death. The stranding included 08 species: one species of balaenopteridae, one species of physeteridae, one species of ziphidae, and five species of delphinidae. From the stranding data recorded on the Algerian west coast, we can conclude that there are two frequent species: the Delphinus delphis (31%) and Stenella ceoruleoalba (21%) of all stranded cetaceans, two commun species: Ziphius cavirostris (17%) and Tursiops truncatus (11%), two uncommon species: Grampus griseus (8%) and Globicephala melas (6%), and two rare species: Physeter catodon (4%) and Baleanoptera acutorostrata (2%). Stranding events occurred all the year round with the highest frequency in winter n=19 (36,54%) and less in spring n=16 (30,77%). Following post-mortem necropsies on the dead animals, 51,92% (n=27) of cetaceans stranded on the Algerian west coast presented criteria related directly or probably to interaction with fishing gears and boat collision. The other causes of death were not determined (n=25, or 48,08%). The D. delphis and S. ceouleoalba were more vulnerable to human and fisheries interaction.