SALMONIDAE, Jarocki or Schinz, 1822

Family SALMONIDAE View in CoL

Genus Salmo Linnaeus, 1758

13. Caspian trout Salmo caspius Kessler 1877

This is an anadromous species, endemic to the Caspian Sea basin. It feeds in the sea and spawns in the rivers of the Southern Caspian Sea, mainly in the Kura River. In the past, it was reported from many rivers along the Iranian coast as far as Gorgan ( Armantrout, 1980; Holčik and Oláh, 1992; Kiabi et al., 1999; Abdoli and Naderi, 2009). With the construction of the Mingachevir and Varvara HPPs (1954-1955), all natural spawning grounds in the Kura River (about 1,000 km from the mouth) were lost. In the sea, it occurs mainly off the western and southern coasts at depths of 40-50 m, but performs rather long horizontal migrations ( Askerov et al., 2001; Bogutskaya et al., 2013). The main limiting factors that have influenced the sharp decline in the abundance of the Caspian trout have been overfishing and overregulation of river flows. Dams on the Terek and Sulak rivers have become the main factor in the population decline ( Pavlov, 2021). The main measures to restore the abundance of this species are artificial reproduction in fish hatcheries ( Matishov, 2010), as well as listing in the RDBs of the Russian Federation ( Pavlov, 2021), the Astrakhan Region ( Pilipenko et al, 2014), the Republics of Kalmykia ( Ochirov, 2014) and Dagestan ( Magomedov, 2009), as well as in the RDB of Tatarstan in category III (rare, declining species) ( Nazirov, 2016), Azerbaijan in category II (rare, declining species) ( Habibbayli and Babayev, 2023) and Kazakhstan in category I (endangered species) ( Meldebekov, 2010). There is no information that existing conservation measures for the Caspian trout have resulted in stabilisation or increase of its abundance, which requires the development of additional protection.

Conclusions

In the course of our study, data on about 90 marine fish species occurring throughout the Caspian Sea were analysed. Firstly, species occurring in Russian waters and endemic species, mainly representatives of the families Gobiidae and Clupeidae (36 species in total), as well as endangered species (5 species) were selected for further analysis. In total, 40 fish species and single cyclostome species were selected. The results of the analysis made it possible to divide the species under consideration into two categories, i.e. species requiring additional conservation measures (13 species) and species not requiring such measures (28 species). It was found that the species most in need of additional protection were generally those with a high commercial value (sturgeon, some herring, Caspian inconnu, etc.). Their abundance has declined for a number of reasons, including climatic changes. Both legal and poaching (IUU fishing) have the greatest negative impact on populations. It has a particularly severe impact on the most valuable commercial targets, such as sturgeon and Caspian inconnu. The regulation of river flows (construction of a network of HPPs) has led to a sharp decline in the abundance of many anadromous species (Caspian lamprey, sturgeon, Caspian inconnu, Caspian trout, etc.). Habitat degradation (dredging, excavation, various land reclamation measures, etc.) also has a negative impact on the populations of the above species, as well as on members of the family Cyprinidae . Unfortunately, at the present time, many of the measures taken to protect these species are ineffective or do not have a sufficient impact to change the situation for the better.

The key issue is the need to comprehensively address the causes that are negatively impacting populations of valuable commercial species, as well as species that require additional conservation measures. We believe that the most effective approach to this problem is the creation of EBSMPAs, i.e. the designation of marine areas (MPAs) for the conservation of vulnerable marine and coastal ecosystems. The main functions of such areas are to maintain and increase biodiversity and to conserve marine ecosystems, i.e. their ability to recover or maintain their natural state ( Kachur, 2020). This strategy of establishing MPAs has already shown positive results in different regions of the world's oceans. Marine protected areas exist in the Indian Ocean (e.g. in the waters of the Seychelles with an area of 210 thousand km 2), a network of MPAs (covering 5% of marine waters) has been established within the economic zone of South Africa, MPAs exist in the North Atlantic, the Mediterranean and the Baltic seas, large MPAs have been created in the waters of the Southern, Pacific and Atlantic Oceans, in the EEZ of Australia, around the overseas territories of France, Great Britain and the USA ( Ivanov et al., 2022). Protected areas currently cover less than 3% of the territorial waters and EEZ of the Russian Federation, while the vast majority of planned MPAs in Russian waters are concentrated in the Arctic and Far East ( Ivanov et al., 2022). The establishment of EBSMPAs in the Caspian Sea will contribute to improving the conservation situation not only of particularly valuable species, but also of the overall biodiversity of the Caspian Sea flora and fauna.

Funding

The preparation of this paper by P.A.P. was carried out within the framework of the Russian State Task of the Astrakhan State Natural Biosphere Reserve (№ 1220516000164-4), by A.M.O. within the framework of the Russian State Task FMWE-2024-0022 of the Shirshov Institute of Oceanology of the Russian Academy of Sciences , by A.G.K. within the framework of the Russian Science Foundation Project N 24-44-20006 "Spatial Planning and Satellite Monitoring of Marine Protected Areas in the Caspian Sea" (2024-2026, https://rscf.ru/en/project/24-44-20006/) .

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