Abstract: The largest multispecies haulout of true seals at Sakhalin Island (Sea of Okhotsk) is located in the mouth of Piltun Bay. It is comprised of ringed (Pusa hispida), spotted (Phoca largha), and bearded (Erignathus barbatus) seals and can include as many as 2,500 animals at one time. Spotted seals numerically dominate the haulout, but ringed seals can also make a notable contribution into the structure and general dynamics of the entire pinniped aggregation during some periods of the year. The haulout is used by ringed seals throughout the ice-free period from June through October. The pattern of haulout occupancy by seal species was studied from 2014 to 2017. Seasonal variations in the number of ringed seals followed a general pattern: annually, the seasonal maximum in number of seals were recorded from the last 10 days of August to the first 10 days of October. This is the period when numerous species of small- and medium-sized fish become abundant in the mouth of Piltun Bay and in the adjacent waters of the Sea of Okhotsk. These fish species constitute the major portion of ringed seal diet throughout its range. The number of ringed seals in the study area has remained stable over the past two decades.
Key Words: ringed seal, Pusa hispida, onshore period, haulout, seal aggregation, Sakhalin Island, Piltun Bay
Page Numbers: 206-215
The Onshore Period in the Annual Life Cycle of Ringed Seals (Pusa hispida) at the Largest Haulout Site of the Species in the North Pacific