Abundance and distribution of the Caspian seals on ice in the Russian part of the Northern Caspian in February — March 2023

The aim of this research was to assess the current abundance of the Caspian seal population on ice in the Russian part of the North Caspian using instrumental methods of aerial survey in the infrared and optical ranges using a manned aircraft and UAV.

The main method of the research was a multispectral aerial survey, the essence of which is to survey seal haulouts synchronously in the infrared and optical ranges. In winter, 90% of all mature individuals gather on the ice substrate of the Northern Caspian for reproduction, lactation and mating and spend a significant part of their time outside the water, which greatly facilitates their detection and counting. The aerial survey was carried out in parallel from two types of aircraft — the La‑8 manned amphibious aircraft and unmanned aerial vehicles equipped with high-resolution cameras in optical and infrared modes, which ensure reliable registration of seals on ice.

Novelty: the advantage of joint use of a manned aircraft and a UAV equipped with special photo and infrared equipment is noted.

As a result of the research, the flights were carried out from February 20 to March 5, 2023 in the daytime in good visibility conditions at an altitude of 200 to 300 m. amounted to 19704 individuals, including 4062 puppies. The animals were located in the southeastern part of the ice cover near the air demarcation line between the Russian Federation and the Republic of Kazakhstan on the ice edge. An increase in the number of seals was recorded due to migrating individuals from Kazakhstan. Breeding of the Caspian seal in winter 2022/2023 proceeded in a satisfactory manner. During the flight, it was found that there were no fresh releases of seals on the coast of Dagestan. Separate old carcasses, partially torn to pieces, were registered only on the shores of the Agrakhan Peninsula.

Practical value: the obtained data are needed to assess the current abundance of the Caspian seal population in the Caspian Sea.

1. Atlas of marine mammals of the USSR. 1980. Moscow. Pishevaya promishlennost. 184 p. (In Russ.)

2. Badamshin B.I. 1960. State of stocks of the Caspian seal // Zoological journal. V. 39. No. 6. P. 898–905. (In Russ.)

3. Badamshin, B.I. 1966. Biology and fishing of the Caspian seal // Fish resources of reservoirs of Kazakhstan and their use. Alma-Ata: Nauka. V. 5. P. 335–338. (In Russ.)

4. Bizikov V.A., Boltnev E.A., Chernook V.I., Petrov E.A., Peterfeld V.A. 2019. Experimental aerial survey of the Baikal seal using long-range UAVs // Trudy VNIRO. V. 175. P. 226–229. (In Russ.)

5. Bizikov V.A., Belyaev V.A., Chernook V.I., Sidorov L.K., Shipulin S.V., Kuznetsov V. V., Vasiliev A. N., Skolsky V. A., Klimov F. V., Marabaev E.N., Erbulekov S. T., Kuanyshev E. K. 2021 a. Estimation of abundance of the Caspian seal basing on the results of aviation survays of the seal ice rookery in the Northern Caspian in 2012, 2020 and 2021 // Use and protection of Russia’s natural resources. No. 4. P. 81–93. (In Russ.)

6. 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 б. Methodological recommendations for the accounting of the Baikal seal (Pusa sibirica) offspring using unmanned aerial vehicles in the Baikal fishery basin. Moscow: VNIRO Publish. 56 p. (In Russ.)

7. Bizikov V. A., Sidorov L.K., Peterfeld V. A., Boltnev E. A. 2022 The use of unmanned aerial vehicles for estimation of Baikal seals population // Biological diversity: study, conservation, restoration, rational use. Kerch, September 13–18, 2022. Mat. of the III Intern. Scient. and Pract. Conf. Simferopol: LLC Typography Arial. P. 108–113. (In Russ.)

8. Kuznetsov V.V. 2017. The impact of fishing on the structure of the Caspian seal population in historical retrospect // Trudy VNIRO. V. 168. P. 14–25. (In Russ.)

9. Kuznetsov V.V., Chernook V.I., Shipulin S.V. 2013. Assessment of the Caspian seal population size in the current time period // Environmental protection in oil and gas complex. No. 5. P. 86–91. (In Russ.)

10. Marine encyclopedic reference book. 1987. V. I / ed. Isanin N.N. Leningrad: Shipbuilding. 512 p. (In Russ.)

11. Popov L.A. 1966. On an ice floe with seals // Priroda. No. 9. pp. 93–101. (In Russ.)

12. Chelintsev N.G. 2000 Mathematical foundations of animal accounting. M.: Tsentroohotkontrol. 431 p. (In Russ.)

13. Chelintsev N.G. 2004 Extrapolation algorithms for aerial surveys of animals // Bul. MOIP. Dep. biol. V.109. iss. 2. P. 3–14. (In Russ.)

14. Chernook V. I., Kuznetsov N. V., Yakovenko M. Ya. 1999. Multispectral survey of the harp seal. Murmansk: PINRO Publish. 73 p. (In Russ.)

15. Chernook V. I., Grachev A. I., Vasiliev A. N., Trukhanova I. S., Burkanov V.N., Solovyov B.A. 2014. Results of instrumental aerial survey of ice-associated seals on the ice in the Okhotsk Sea in May 2013 // Izvestiya TINRO. V. 179. P. 158–176. (In Russ.)

16. Chernook V. I., Kuznetsov V. V., Kuznetsov N. V., Shipulin S. V., Vasiliev A.N. 2015. Instrumental aerial surveys of Caspian seals (Phoca caspica) on breeding grounds // Marine Mammals of the Holarctic. V. 2. P. 283–292. (In Russ.)

17. Chernook V. I., Trukhanova I. S., Vasiliev A. N., Grachev A. I., Litovka D.I., Burkanov V.N., Zagrebelny S.V. 2018. Abundance and distribution of phocid seals on ice in the western Bering Sea in spring, 2012–2013 // Izvestiya TINRO. V. 192. P. 74–88. (In Russ.)

18. Shafikov I.N. 2008. Express assessment of the maximum number of the White Sea population of the harp seal (Phoca groenlandica) using pup data // Marine Mammals of the Holarctic. Odessa: Astroprint Publish. P. 483–486