STURGEONS
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Sterlet Beluga Pallid sturgeon Baltic sturgeon Lake sturgeon
numbers in certain parts of their range. The Syr-Dar shovelnose sturgeon is now believed to be extinct in the wild for this reason. Sturgeons will migrate when it is time for spawning, and changes to the river systems—such as the building of dams, canals, bridges, and other obstructions—may block off the usual routes back to their spawning grounds. Those species that inhabit the oceans grow to a larger size than their freshwater relatives because they can find food more easily there throughout the whole year.
Spawning Rituals Sturgeons usually spawn every three to five years, rather than annually. Having spawned, marine sturgeons then head back toward the sea. By this stage they will be weakened and in poor condition due to the effort of making the journey upriver to spawn, and by having to cope with the changing water conditions that affect their biology. Furthermore, they will not have fed during their migration. The young sturgeons, too, will soon be starting to move down river. Some of them will reach the sea by the