@ 2021. S.T. Yerbulekov, Ye.K. Kuanyshev, F.V. Klimov, S.M. Sarsengaliev, S.V. Ukhov, V.P. Mishchenko.
Kazakhstan Agency of Applied Ecology, LLP (KAPE); KazEkoProekt, LLP (KEP). By the order of North Caspian Operating Company N.V. (NCOC).
The Caspian Seal in the Kazakh Part of the Caspian Sea (2006-2016)
Conclusions based on the results of the conducted surveys
The results of the surveys performed in 2008-2013 provided a reliable acknowledgment that the Caspian seal habitat covers the Northern Caspian and the coastal waters of the Middle Caspian. When migrating to the north direction, the seals use a “migration corridor” from the border with Turkmenistan to the Zhaiyk River (the Ural River) estuary along the Kazakhstan coast, extending from the coast approximately to isobath 50 m. The continuous use of this corridor over a number of consecutive years confirms its importance for seal migrations. This fact needs to be taken into consideration when assessing the potential impact of commercial activities, including navigation and petroleum operations.
The survey data shows that some seals prefer foraging in certain habitats, for example, in shallow waters or in certain foraging areas confined to open waters or coastal areas.
The shallow waters of the northeastern part of the Caspian Sea, from the Komsomolets Bay to the Zhayyk River delta, used by seals for migration, foraging and resting are their autumn habitat. It is most likely that this area is also used by a major part the breeding adult population waiting for ice formation. Therefore, it is extremely important to take into account potential impact of any operations on the seals in this particular area in the autumn period.
Autumn-winter migration has a more complex nature than it was assumed before. The surveys acknowledged the behaviour of seals when they entered and left the ice-covered area a number of times, and also migrated for feeding to the southern areas.
The majority of resurfacing and diving events was registered at 3-15 m depths. A major part of the seals did not dive to the depths below 50 m. Diving to 100 m depth or below was observed very rarely. The maximum diving depth was closely related to bathymetric conditions in the diving area. During the feeding period, diving duration did not exceed 5 minutes.
The Company’s (NCOC – Kaspika’s note) initiative to research Caspian seals with satellite tagging is a new technology to survey such an endemic species in the Caspian Sea.
Understanding of the identified aspects of seal life pattern is necessary in order to minimize a potential negative impact of the Company’s (NCOC – Kaspika’s note) operations and infrastructure on the seals population. Satellite remote measuring data together with the data received from other surveys allows to get the information required for planning operations in this direction.
Cumulative data on movements of the Caspian seal acquired with use of satellite remote measuring in various years can be used for a more careful analysis of habitats and migration routes alongside with other results of surveys (aerial surveys, vessel observations, etc.).
Further development of satellite remote measuring data through subsequent surveys would be very useful because it allows to identify the regularities in seals behaviour. Seals tagging in spring and summer could be considered as a primary direction of future surveys because the behavioural range in this period is significantly wider than in winter.
To download the scientific paper: Yerbulekov, Kuanyshev et al., 2021.
Photo by A. Kovalenko: a Caspian seal, the Northern Caspian, Kazakhstan, October, 2021.