ProMED-mail has reported on the mass mortality of over 300 Northern Fur Seals and sea lions on Tyuleniy Island in the sea of Okhotsk off the coast of Siberia. Dead marine birds were also found in the vicinity of affected seals.

Although not confirmed, it is presumed that Highly Pathogenic Avian Influenza strain H5N1 is responsible.

Northern Fur Seals are now regarded as a threatened species both by overhunting and climate change.  Mass mortality among marine mammals due to HPAI has previously been recorded in diverse marine mammal species off the coasts of Maine, Peru and Argentine from January onwards.