Mass strandings of seven toothed and baleen whale species in Northern Norway in March 2020 call for further investigation

Abstract

Monitoring whale strandings are a key aspect of ecosystem management as stranded animals can provide indications on ecosystem health, pollution and adverse efects due to anthropogenic activities. Most mass mortality events are reported for toothed whales and rarely involve baleen whales. In the course of one month in spring 2020, 17 whales belonging to seven diferent species, stranded on the shores of Northern Norway, above the Arctic circle. This multi-species event included humpback (Megaptera novaeangliae), fn (Balaenoptera physalus) and sperm whales (Physeter macrocephalus), that were accompanied by northern bottlenose whales (Hyperoodon ampullatus), a white-beaked dolphin (Lagenorhynchus albirostris), a long-fnned pilot whale (Globicephala melas) and a harbour porpoise (Phocoena phocoena). We discuss some potential causes of death based on the previous literature and available information for the area, highlighting the need for further investigation on cetacean strandings at high latitudes. Ultimately, the reasons for the stranding could only be identifed by a thorough examination of all the animals, which was unfortunately not conducted. As the threats to polar ecosystems and access to local shores are likely to increase, reports of cetacean mortality are also expected to surge, particularly in high latitude regions where climate variations and anthropogenic activities are increasing. This study makes recommendations for future steps and considerations for monitoring networks and standardized sampling methods for future marine mammal stranding events. Finally, we suggest that national and international eforts based on the collaborative relationships are implemented, considering the multiple facets of animal ecology and health as an achievable step in the near future.