The taxonomy of anadromous Ponto-Caspian shads remains in question, with molecular studies revealing low genetic divergence between species inhabiting the Black, Caspian and Aegean Sea basins (Faria et al. 2006; Vernygora et al. 2018).

In the absence of a definitive taxonomic revision, the Red List continues to follow the nomenclature provided by Fricke et al. (2023).

The Caspian Shad is believed to be declining due to a series of plausible threats, but appears to remain abundant throughout its relatively wide range. It is therefore assessed as Least Concern.

This species is endemic to the Caspian Sea basin, plus the lower reaches of major inflowing rivers. It was introduced to the Aral Sea basin during the early 20th century, but did not become established there.

The Caspian Shad's population trend has not been quantified, and there is little information regarding its status. Given that there exist a number of ongoing plausible threats (see 'Threats'), it is estimated to be in decline.

The Caspian Shad is euryhaline and semi-anadromous, with some subpopulations entering the lower reaches of larger rivers flowing into the Caspian Sea in order to spawn, while others utilise coastal lagoons or reproduce in the sea itself. It exhibits a preference for warmer water with temperatures of no less than 8-11°C, and subpopulations that spawn in the Volga and other areas in the north of the Caspian basin migrate to the southern portion during winter. Outside the reproductive season adult individuals are largely pelagic, and many winter at depths of 30-40 metres or more.

Migratory subpopulations begin to move towards their spawning grounds in late March. Migration peaks in mid- to late-April at water temperatures of 9-14°C, and ends by early May. Males tend to migrate before females, and spawning itself takes place during May and June. This species is a fractional spawner, with females releasing several thousand eggs in batches up to three times per week. The eggs are semi-pelagic to demersal, and most are released in the upper 3 metres of the water column. Migratory post-spawning adults remain in nearby offshore foraging areas until October or November. Juveniles undertake a pre-winter migration in their first year, and begin to move before the adults. Both males and females reach sexual maturity at 2-3 years of age, with the majority spawning for the first time at 3 years. They are reproductively active for 2-5 years, with each individual spawning up to 4 times during its lifetime. Maximum age in both sexes is 8-9 years, and maximum recorded size is 28.0 cm standard length.

This species feeds primarily on zooplankton, with copepods and mysids comprising the bulk of the diet, although some phytoplankton and small fishes are taken as well. In rivers it mostly preys on cladocerans and other crustaceans. Foraging intensifies during the post-spawning summer period, and less food is taken during the winter.

The Caspian shad is an important component of the diet of several predatory species, including Caspian Seal (Pusa caspica), Wels Catfish (Silurus glanis), and Grey Heron (Ardea cinerea).

No major threats have been conclusively identified. However, a series of plausible threats are ongoing, with some coastal wetlands in the Caspian Sea basin imperilled by a range of anthropogenic factors, including eutrophication, sedimentation, pollution from agricultural, domestic and industrial sources, and introduction of invasive plant and animal species.

Moreover, ongoing expansion of the invasive Warty Comb Jelly (Mnemiopsis leidyi) in the Caspian Sea basin is likely to have negatively impacted the Caspian shad population. First recorded in 1999, the jelly was probably transported from the Black Sea or Sea of Azov in ship ballast water. It has since spread throughout the basin, and has been linked to significant declines in the biomass of zooplankton and planktivorous fishes. Although its specific effect on the Caspian Shad population has not been documented, a general decline in native shads (Alosa spp.) and other fish species has been reported by a number of researchers.

In addition, it is likely that a decrease in the water level of the Caspian Sea, as projected under a number of future climate change scenarios, could drive a further reduction in the extent of suitable habitat.

The Caspian shad was among the most important commercial fish species in the Caspian Sea until the early 1960s, when shad fishing was prohibited in the northern part of the basin in order to preserve stocks of beluga (Huso huso) and other sturgeons (Acipenser spp.). It is still exploited on a commercial basis in the western Caspian, e.g., in the Republic of Dagestan (Russia), where it is mostly caught with seines and gillnets and marketed for human consumption.

Estimation of the annual catch is complicated because landing records do not usually separate Caspian shad from congeners such as Caspian marine shad (Alosa braschnikowi), Caspian anadromous shad (Alosa kessleri), and Volga shad (Alosa volgensis). In the early 20th century, annual landings of Alosa spp. in the Caspian basin (excluding Iranian waters) exceeded 330,000 tonnes, but currently average 95-110,000 tonnes of which Caspian shad is estimated to contribute fewer than 25 tonnes. This decrease is partly attributable to the fishing ban, but also reduced effort by local fishers who increasingly target introduced mullets (Chelon spp.).

No species-specific conservation actions are in place, although the Caspian shad may have benefited from the various fishing regulations in place throughout the Caspian Sea basin. The recent rise in Caspian Sea water levels (> 2 metres since 1978) may have increased the availability of spawning and nursery habitat.

Future research should ideally focus on assessing the species' population size and trend, plus the extent to which it may have been negatively impacted by the ongoing plausible threats.