Table 1. Biological information on seals providing sera samples in this study.
| Location a) | Species | Sampling Date | Number of seals | Seal biological feature | ||
|---|---|---|---|---|---|---|
| Year | Period | Sex (M/F) b) | Life stage (P/Y/J/S/A) c) | |||
| Cape Erimo (A) | Harbor seal (Phoca vitulina stejnegeri) | 2013 | Aug 31−Oct 23 | 3 | 1/2 | 0/3/0/0/0 |
| 2014 | Aug 22−Nov 4 | 5 | 0/5 | 0/2/3/0/0 | ||
| 2015 | May 25−Oct 14 | 21 | 10/11 | 1/16/3/0/1 | ||
| 2016 | May 24−Nov 1 | 34 | 18/16 | 1/26/3/1/3 | ||
| 2017 | May 23−Oct 19 | 55 | 16/39 | 11/10/13/4/17 | ||
| Total | 118 | 45/73 | 13/57/22/5/21 | |||
| Spotted seal (Phoca largha) | 2017 | Sep 14 | 1 | 0/1 | 0/0/0/1/0 | |
| Nemuro (B) | Spotted seal (Phoca largha) | 2016 | Dec 5 | 1 | 0/1 | 0/1/0/0/0 |
| 2017 | Dec 1–8 | 5 | 1/4 | 0/0/0/1/4 | ||
| Total | 6 | 1/5 | 0/1/0/1/4 | |||
| Akkeshi (C) | Harbor seal (Phoca vitulina stejnegeri) | 2013 | Apr 22 | 1 | 0/1 | 0/0/0/0/1 |
| 2016 | Jun 8 | 1 | 1/0 | 1/0/0/0/0 | ||
| Total | 2 | 1/1 | 1/0/0/0/1 | |||
| Ribbon seal (Histriophoca fasciata) | 2014 | May 1 | 1 | 0/1 | 0/0/1/0/0 | |
| Ringed seal (Phoca hispida) | 2014 | Sep 2 | 1 | 0/1 | 0/1/0/0/0 | |
| Rebun Island (D) | Spotted seal (Phoca largha) | 2013 | Dec 18–25 | 3 | 0/3 | 0/0/1/0/2 |
| Bakkai (E) | Spotted seal (Phoca largha) | 2013 | Dec 24–26 | 2 | 0/2 | 0/1/0/0/1 |
| Soya (F) | Spotted seal (Phoca largha) | 2017 | Oct 20 | 1 | 1/0 | 0/0/1/0/0 |
| Teuri Island (G) | Spotted seal (Phoca largha) | 2016 | May 20 | 1 | 0/1 | 0/0/1/0/0 |
| Rausu (H) | Spotted seal (Phoca largha) | 2018 | May 17 | 1 | 0/1 | 0/1/0/0/0 |
| Hidaka (I) | Ribbon seal (Histriophoca fasciata) | 2014 | May 13 | 1 | 1/0 | 1/0/0/0/0 |
a) Capital letters in parentheses refer to the sampling locations in Fig. 1. b) M/F: Male/Female. c) P/Y/J/S/A: Pup/Yearling/Juvenile/Subadult/Adult.