Alosidae, Svetovidov, 1952

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 62

Family Alosidae

True shads

Four genera are placed in this family: Alosa , Brevoortia , Sardina , and Sardinops . Only Alosa enters freshwaters in West Asia. Sardina pilchardus is a common species in the Mediterranean and Black Seas and is occasionally found in estuaries. It is not known to enter freshwater habitats regularly and is therefore excluded from the coverage of this book. Alosa are anadromous or form landlocked populations in the Atlantic, the Mediterranean, Caspian, and the Black Sea basins. Six species occur in North America. In the Caspian basin, three species, A. braschnikowii , A. saposchnikowii , and A. sphaerocephala , are fully marine and do not enter freshwater habitats. Caspian A. caspia and Black Sea A. maeotica regularly occur in coastal regions of Limans and river estuaries but only regionally and rarely enter freshwater regions to spawn. Only Caspian A. kessleri and A. volgensis , as well as Black Sea A. immaculata , are anadromous and migrate longer distances upriver. Black Sea A. tanaica and widespread A. agone regularly enter lower regions of rivers and freshened coastal lakes. Alosa volgensis from the northern Caspian basin may have occurred in the waters of the southern Caspian Sea. Still, this species was never identified from the region and went extinct in the 20 th century.

Shads are very sensitive to environmental impacts such as impoundment, water pollution, and overfishing. Most anadromous species have sharply declined during the 20 th century. Species undertaking long upriver migrations, such as A. immaculata and A. kessleri , are very vulnerable as most of their original spawning sites are no longer accessible, their spawning migrations being interrupted by dams and other alterations in river morphology. The status of species or populations spawning in the sea and lower stretches of rivers is better, as they can often find spawning habitats below dams.

The systematics of shads need critical review, and molecular data suggest that all Ponto-Caspian species are very closely related or frequently have been the victims of introgressive hybridisation. The Ponto-Caspian shads may form a recently evolved “species flock,” as it is known from cichlids in East Africa. Several subspecies and “forms” have been described from the Black and Caspian Seas, and their status needs to be revised based on the basis of adequate fresh material and molecular characters. Further reading. Berg 1949b (diversity, biology); Whitehead 1985 (diversity); Holčík 1986 (diversity, biology, distribution).

Keys to species of Alosa in freshwaters of West Asia

Caspian basin

1a - 59–92 gill rakers, shorter than branchial filaments. ……………… A. kessleri

1b - 70–180 gill rakers, about as long as or longer than branchial filaments. ………………2

2a - Head length 23–26 % SL; 99–105 gill rakers, about as long as or longer than branchial filaments, with well-developed spines. ……………… A. volgensis

2b - Head length 25–28 % SL; 70–180 gill rakers, long and close together, 1.5–2 times longer than branchial filaments in individuals larger than 150 mm SL, without spines. ……………… A. caspia

Mediterranean and Black Sea basin

1a - Teeth on palatine and vomer absent or poorly developed. ………………2

1b - Teeth on palatine and vomer well developed. ………………3

2a - Teeth on palatine and vomer poorly developed;

66–96 gill rakers, longer than branchial filaments. ……………… A. tanaica

2b - No teeth on palatine; 28–50 gill rakers (rarely up to

60) about as long as branchial filaments in individuals larger than 220 mm SL. ……………… A. agone

3a - 36–69 gill rakers, longer than branchial filaments. ……………… A. immaculata

3b - 29–39gill rakers,about as long as branchial filaments. ……………… A. maeotica