Abundance and distribution of the Ladoga ringed seals in anomaly warm winter 2020: results of the arial survey using drones

The aim of this research was to assess the abundance and distribution of the Ladoga ringed seals during anomaly warm winter 2020.

The main method of the research was arial survey of the seals using drones. Taking into account complete absence of ice on the surface of the Ladoga Lake at the time of the survey (April-May, 2020) a new method for assessing the seals abundance was used that was based on the extrapolation of the seals density along the coast line using barrier model in R Statistic Software.

As a result of the research, it was shown that during anomaly warm winter, in the absence of ice fields on the Ladoga Lake, the seals formed rookeries directly on the co0astline of remote islands and hardly accessible rocky inlets in the northern part of the Ladoga Lake. Total number of the seal population, estimated basing on the arial survey data was 5,680 individuals.

Conclusion: The study showed that the islands, skerries and rocky inlets in the northern part of the Ladoga Lage act as a kind of refuge for the Ladoga ringed seal during anomaly warm ice-free winters. These environments provide the seals proper substrate suitable for bedding and shelter. Basing on the survey data, the population of the Ladoga seal in the northern part of the Ladoga Lake was amounted to 5,680 individuals which is close   to the estimates obtained for the entire Ladoga Lake in 2012–6.5 thousand individuals. Thus, the data of the 2020 air survey allow us to make a preliminary conclusion that the population of the Ladoga seal has not changed significantly over the past 8 years.

1. Agafonova E. V., Verevkin M. V., Medvedev N. V., Sipila T., Sokolovskaya M. V., Shakhnazarova V. Ju. 2006. Distribution of haul-out sites of Ladoga ringed seals (Phoca hispida ladogensis) and their abundance on the islands of the Valaam Archipelago (Lake Ladoga) in summer // «Dynamics of game animals populations in northern Europe Proceedings». The 4th Intern. symp. 18–22 Sept., 2006, Petrozavodsk, Karelia, Russia Petrozavodsk: KarRC RAS, P. 5–9 (In Russ.)

2. Agafonova E. V., Verevkin M. V., Sagitov M. V., Sipila T., Sokolovskaya M. V., Shakhnazarova V. Ju. 2007. The Ringed seal in Lake Ladoga and the Valaam Archipelago. Vammalan Kirjapaino Oy. 61 p. (In Russ.)

3. Agafonova E. V., Verevkin M. V., Sipila T. V., Sokolovskaya M. V., Shakhnazarova V. Ju. 2010 Monitoring of the Ladoga ringed seal (Pusa hispida ladogensis nordq. 1899) population on haul-outs at the islands of the Valaamo archipelago // Population status and conservation of the Ladoga ringed seal (Phoca hispida ladogensis): Proceedings (March, 24–25, 2009, St. Petersburg, Russia) St. Petersburg: P. 3–12. (In Russ.)

4. Antoniuk А.А. 1975. Estimation of the total population density of the Lake Ladoga seal (Pusa hispida ladogensis) // Russian Journal of Zoology. V. 54(9). P. 1371–1377. (In Russ.)

5. Bizikov V. A., Peterfeld V. A., Chernook V. I., Kuznetsov N. V., Petrov E. A., Bobkov A. I., Tkachev V. V., Sidorov L. K., Boltnev E. A. 2021. Methodological recommendations for the accounting of the Baikal seal (Pusa sibirica) offspring using unmanned aerial vehicles in the Baikal fishery basin. Moscow: VNIRO Publish. P. 56. (In Russ.)

6. Bizikov V. A., Lukina Ju. N., Sidorov L. K., Sabirov M. A., Trukhanova I. S. 2022. Abundance and distribution of the Ladoga seal in anomalous warm winter 2020: estimate based on the results of the aerial survey // Proceedings XI Congress of the Theriological Society at the RAS (14–18 March 2022, Moscow, Russia IPEE RAS). KMK Scientific Press Ltd.. p. 38. (In Russ.)

7. Verevkin M. V. 2002. Results of the aerial survey of the ringed seals in the Ladoga Lake // «Dynamics of game animals populations in northern Europe» Proceedings The 3rd Intern. symp. 16–20 June, 2002 г., Sortavala) Petrozavodsk: Karelian Research Centre of RAS. P. 202–204. (In Russ.)

8. Verevkin M.V., Vysotskiy V.G. 2013. Current status of the Ladoga ringed seal Pusa hispida ladogensis (Nordquist, 1899) // Vestnik SPSU. Ser. 3. Iss. 4. P. 14–25. (In Russ.)

9. Verevkin M. V., Medvedev N. V., Silila T. 2006. By-catch mortality of the Ladoga seal (Phoca hispida ladogensis) population // Marine mammals of the Holarctic. Collect. papers VI Intern. Conf. Saint-Petersburg. September 10–14. P. 130–133. (In Russ.)

10. Verevkin M. V., Trukhanova B. C., Sipila T. 2010 a. The Ladoga ringed seal (Pusa hispida ladogensis Nordquist, 1899) — fisheries interactions on Lake Ladoga // Population status and conservation of the Ladoga ringed seal (Phoca hispida ladogensis): Proceedings (March, 24–25, 2009, St. Petersburg, Russia). St. Petersburg: P. 37–41. (In Russ.)

11. Verevkin M. V., Sagitov R. A., Sipila T. 2010 b. The Ladoga seal (Pusa hispida ladogensis Nordquist, 1899) of the Lake Ladoga // Population status and conservation of the Ladoga ringed seal (Phoca hispida ladogensis): Proceedings (March, 24–25, 2009, St. Petersburg, Russia). St. Petersburg, P. 32–36. (In Russ.)

12. Glazov D. M., Kuznetsova D. M., Soloviova M. A., Ulichev V. I., Rozhnov V. V. 2019. Use of the Lake Ladoga area by the Ladoga seal (Pusa hispida ladogensis) in the autumn-winter period, based on satellite telemetry data // Russian Journal of Zoology. V. 98 (6). P. 1371–1377. (In Russ.)

13. Zheglov V. A., Chapskiy K. K. 1971. Experience of aerial survey of ringed seal, grey seal and their lairs in the bays of the Baltic Sea and the Ladoga Lake // Marine Mammal Research. Kaliningrad: AtlantNIRO Pudlish. Iss. 39. P. 323–342. (In Russ.)

14. Zemskiy V. A., Filatov I. E. 1986. Population abundance of the Ladoga seal according to the aerial survey in the spring, 1985 // «Research on the conservation and rational use of marine mammals». Proceedings. Arkhangelsk. 1986. P. 154–156.

15. Zubov A. I. 1965. Activities on seal harvest establishment on Ladoga Lake and in the Gulf of Finland // Fisheries: № 5. P. 22–24. (In Russ.)

16. Red Data Book of the Russian Federation. 2021. V. Animals. 2-nd edition. Moscow: VNII Ecologia. 1128 p. (In Russ.)

17. Medvedev N. V., Sipila T., Verevkin M. V. 2010 The status of the Ladoga seal (Phoca hispidalLadogensis) Population, main threats and recommended conservation actions // Population status and conservation of the Ladoga ringed seal (Phoca hispida ladogensis): Proceedings (March, 24–25, 2009, St. Petersburg, Russia). St. Petersburg. P. 51–58. (In Russ.)

18. Medvedev N. V., Sipila T., Kunnasranta M., Hyuvarinewn H. 2000. Ladoga seal // Biodiversity inventories and studies in Zaonezhski peninsula and northern shore of Lake Ladoga (express information materials). Petrozavodsk, Karelia. P. 325–332. (In Russ.)

19. Medvedev N. V., Sipila T. 2010. Wintering and breeding peculiarities of ringed seal (Phoca hispida ladogensis) in the northern part of Lake Ladoga // Transactions of Karelian Research Centre of RAS. № 1. P. 86–94. (In Russ.)

20. Medvedev N. M., Sipila T., Verevkin M. V. 2006. Peculiarities of the Ladoga ringed seal (Phoca hispida ladogensis) distribution across the lake water area in the ice-covered period // Marine mammals of the Holarctic. Collec. papers VI Intern. Conf. Saint-Petersburg. September 10–14, 2006. P. 358–360. (In Russ.)

21. Noskov G. A., Gaginskaya A. R. 2002. Red Data Book of the Leningrad region. V. 3. Animals. Sankt-Peterburg: 480 p. (In Russ.)

22. Platonov N. G., Mordvintsev I. N., Rozhnov V. V. 2013. The possibility of using high resolution satellite images for detection of marine mammals // Izvestiya RAS. Biology Bull. № 2. P. 217–226. (In Russ.)

23. Sokolov A.S. 1958 а. On the feeding of the Ladoga seal and its potential for hunting // Fisheries. № 10. P. 25–27. (In Russ.)

24. Sokolov A.S. 1958 б. Some data on the biology of the Ladoga seal // Uchenye zapiski A. I. Herzen SPI. V. 179. Leningrad: A. I. Herzen LGPI Publish. P. 97–112.

25. Tormosov D. D., Filatov I. E. 1977. On the article «Estimation of the total population density of the Lake Ladoga seal» by A. A. Antoniuk // Russian Journal of Zoology. V. 56 (9). P. 1425–1427. (In Russ.)

26. Tormosov D. D., Filatov I. E. 1984. Modern status of seals populations ion the Baltic Sea and the Ladoga Lake // Marine mammals. Moscow: Nauka. P. 276–284. (In Russ.)

27. Trukhanova I. S., Sagitov R. A., Verevkin M. V., Alekseev V. A., Andrievskaya E. M., 2012. Ladoga ringed seal and fishery: why did the conflict arise? // Society. Environment. Development (Terra Humana). № 2. P. 232–238. (In Russ.)

28. Trukhanova I. S. 2013. The state of the population of the Ladoga ringed seal (Pusa hispida botnica) in the context of long-term and seasonal changes in environmental factors. PhD theses. Sankt Peterburg: SPbSU. 17 p. (In Russ.)

29. Filatov I. E. 1978. Seasonal distribution of the seal in the Ladoga Lake // Proceedings of the VII ALL-Union Meeting of Marine mammals. Moscow: P. 342–343. (In Russ.)

30. Filatov I. E. 1984. Biology and commercial value of Ladoga ringed seal. PhD theses. Kiev, 20 p. (In Russ.)

31. Filatov I. E. 1990. The Ladoga ringed seal // Rare and Endangered Mammal Species of USSR. Moscow: Nauka, P. 57–64. (In Russ.)

32. Chapskiy K. K. 1932. The Ladoga seal and its commercial potential // Bulletin of the Institute of Ichthyology. Leningrad, V. XIII, fasc. 2. P. 147–157. (In Russ.)

33. Hilton-Taylor, C. (compiler). 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK. 61 p.

34. Kunnasranta M., Hyvärinen H., Sipilä T., Koskela J. 1999. The diet of the Saimaa ringed seal Phoca hispida saimensis // Acta Theriologica. V. 44(4). P. 443–450.

35. Kunnasranta M., Hüvarinen H., Sipilä T., Medvedev N. 2001. Breeding habitat and lair structure of the ringed seal in northern Lake Ladoga in Russia. // Polar Biology. V. 24. P. 171–174.

36. McHugh M.L. 2012. Interrater reliability: The kappa statistic // Biochemia Medica. V. 22 (3): P. 276–282. doi:10.11613/bm.2012.031

37. Sipilä T., Medvedev N., Kunnasranta M., Bogdanov V., Hyvärinen H. Species. 2002. Present status and recommended conservation actions for the Ladoga seal (Phoca hispida ladogensis) population // WWF Suomen Report. N.15. Helsinki. 30 p.

38. Trukhanova I. S., Gurarie E., Sagitov R. A. 2013. Distribution of hauled–out Ladoga ringed seals (Pusa hispida ladogensis) in spring 2012 // Arctic, V. 66(4). P. 417–428.

39. Efron B. 1979. Bootstrap Methods: Another Look at the Jackknife // Annals of Statistics. V. 7, no. 1. P. 1–26.

40. John G. Cragg. 1971 Some Statistical Models for Limited Dependent Variables with Application to the Demand for Durable Goods // Econometrica. V. 39, No.5. P. 829–844