Caspian Sea: State of the Environment 2019

In February 2015, the main Caspian seal whelp- ing grounds were located on ice fields with an ice thickness of 10–15 cm, in both the Rus- sian Federation and Kazakhstan sectors of the Northern Caspian. The distribution pattern of producing females was the same as in 2014, when the whelping grounds were located along the ice edge from east to west. In the western part of the Northern Caspian, the Caspian seal population varied considerably from season to season in 2015, from a minimum of 19,310 in summer to a maximum of 68,040 in spring and autumn. Photographs showed that the seals used 700 autumn grounds on sandbanks, twice as many as in autumn 2014. The main biological indicators for broodstock and seal pups in autumn 2015 were within the normal range for this period. Compared with 2014, the average density (0.74 seals/km 2 ) in the Northern Caspian increased by 14 per cent in spring. The fattening average concentrations of Caspian seals in the sea increased by 42 per cent in summer and by 232 per cent in autumn (Kuznetsov et al. 2016). The inter-annual trend in the taxonomic com- position and quantitative indicators of the mac- rozoobenthos in the north-eastern part of the Caspian Sea is characterized by minor fluctua- tions. The taxonomic composition in the study area comprised 53 taxa in summer 2017 com- pared with 59 in 2016, and 31 taxa in autumn 2017 and autumn 2016. Numbers were slightly higher in summer 2017 than in summer 2016, but the biomass was slightly lower than in 2016. Worms made up a dominant proportion of hyd- robionts in summer 2017 and 2016, while worms and molluscs dominated the biomass. In autumn 2017, the numbers and biomass were slightly higher than in autumn 2016. Worms dominated in numbers, and shellfish in biomass. The pop- ulation trend has been highly variable in recent years, as illustrated in Table 5.7 below. As in previous study years (2007–2014), the community structure in 2015 was characterized by the persistent dominance of worms (in terms of numbers) and molluscs (in terms of biomass). The composition of dominant species in the lead- ing groups experienced a small degree of change.

a commercial biomass of 2,460 tons, represent- ing declines by factors of 2.4 and 2, respectively, when compared with 2010. The stellate sturgeon catch in 2016 was no higher than 42 kg. Sterlet. Over the last five years of observation, the number of sterlet has fallen from 0.166 million to 0.104 million specimens, and the commercial biomass has decreased from 34.3 to 29.2 tons. Beluga. There was a steady decrease in the ab- solute number of beluga (from 0.466 million to 0.228 million) and commercial stocks of the fish (from 8,080 to 4,060 tons) between 2010 and 2015. Fishing for Caspian marine species is under- going a revival on the basis of reserve species: common sprat and all species of sea herring (Caspian marine shad, saposhnikovi shad and Alosa caspia, Atherina and mullet). The priori- ty is to exploit aquatic biological resources near the Dagestan coast. In the Russian Federation, the raw material base of the most abundant commercial semi-mi- gratory and river fish species (Caspian roach, bream, carp and pike) is experiencing significant stress. The species bear the brunt of the pressure from fishing, with 82.6 per cent (49,200 tons) of the allowable catch and recommended catch uti- lized. At the same time, stocks of such species as catfish, pike and “other” fish are satisfactory. Currently, commercial resources of marine fish species with sufficient reserves (migratory sea herring, common sprat, Atherina, mullet) con- tinue to be shaped primarily by natural popula- tion decline. According to the results of an aerial survey con- ducted in 2012, the Caspian seal population was estimated to be 270,000–330,000. The correction of aerial photographs of broodstock from 2012 using ship route registration in 2015 confirms that the total Caspian seal population in the Cas- pian Sea has stabilized. Preliminary calculations showed that the seal population was projected to remain at up to 266,000 and commercial sealing levels in the Russian Federation region could be set at 6,000.

62