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

Abstract

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.