A vagrant walrus (Odobenus rosmarus) in Finland

Authors

• Henry Pihlström University of Helsinki
• Antti Halkka WWF Finland Baltic Seal Group
• Sanna Sainmaa Korkeasaari Zoo
• Maiju Lanki Metsähallitus Parks & Wildlife Finland
• Outi Simola Finnish Food Authority
• Antti Oksanen Finnish Food Authority
• Valdis Pilāts Nature Conservation Agency
• Eero Vesterinen University of Turku
• Jaakko Pohjoismäki University of Eastern Finland
• Ari Puolakoski University of Helsinki
• Janne Granroth University of Helsinki
• Risto Väinölä University of Helsinki

Abstract

In July 2022, a vagrant female Atlantic walrus (Odobenus rosmarus rosmarus) was seen on the south coast of Finland. The same individual, which was called ’Stena’ in the international press, had previously been observed in the waters of several other European countries along the North and Baltic Seas. By the time the animal reached Finnish waters it was in poor condition and did not survive a rescue attempt. Post-mortem investigation revealed that the animal was malnourished and its digestive tract was almost empty, but trace amounts of DNA from bivalves and other aquatic invertebrates could be recovered. However, apart from minor age-related ailment and superficial skin wounds, the walrus showed no obvious signs of illness or injuries. Dental wear suggested that the animal was at least 20 years old. Its body and cranial measurements, including tusk length, were well above the average size for a female Atlantic walrus. Mitochondrial DNA supported its origin in the eastern Barents Sea populations. The specimen was mounted and put on display in the Natural History Museum, Helsinki. This is the first confirmed free-ranging walrus observation in the northern part of the Baltic Sea and Finland.