black sea red data book - Department of Biology

Biology. A migratory, anadromous species, which enters the rivers in April-October.
Reproduction in May-June; a female can lay 20,000-360,000 eggs. Sexual maturity
reached when five (male) or seven (female) years old. Feeds mainly on fish, also on
molluscs, crustaceans and chironomids. Caught mainly with stake nets, drift nets and
beach seines. A highly esteemed table fish. A ponto-caspian relict.
Population trends. Like Acipenser guldenstaedti, the population of this species has
dropped by 80 % in 1940-1960 relative to the previous two decades (1920-1940). In
the catches of the northern zone of the Romanian littoral (Chituc - Vadu), in May
1991 this species represented 50 kg in May (15 specimens); in June 30 kg (11
specimens) and in August 14 kg (358 specimens, all juveniles). The catches recorded
for the entire Romanian littoral were: 1989-19,000 t; 1990-4,0001, 1991-15,000 t, for
Bulgaria 15,0001 (1989), for US 27,0001 (1989), 15,000 (1990), 15,000 (1991). In
1993-1994, the exploitable stock of the north-western area of the Black Sea was
assessed at 220,000 specimens.
Threats. Overfishing, chemical pollution, large-scale dam building which block the
traditional routes of migration and access to spawning grounds.
Conservation measures taken. This species has been under protection in Turkey
since 1997. Total catch was 110 tons in 1995. A special recovery and monitoring
programme was started by the Turkish Marine Research Foundation in the Sakarya
and Kizilirmak estuaries.
Conservation measures proposed. Protection of spawners during migration and
spawning; protection of spawning and feeding areas; artificial reproduction; strict
national measures to reduce poaching.
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