The numbers of Alosa agone have declined due to barriers such as dams in their local areas. These barriers prevent them from getting upstream to their spawning grounds and reproducing. Improved water quality in some landlocked lakes has increased their numbers in recent years.
Biology
The "twaite shad" are known to be very adaptive and variable as they form landlocked populations in Italy and its neighboring areas, including the western Balkans. They can modify their morphology and biology according to their environment. Therefore, Alosa agone, just like many Alosa species, can be either marine or freshwater fish.