Sawfish
The pregnancy lasts several months. There are 1–23 young in each sawfish litter, which are long at birth. In the embryos the rostrum is flexible and it only hardens shortly before birth. To protect the mother the saws of the young have a soft cover, which falls off shortly after birth. The pupping grounds are in coastal and estuarine waters. In most species the young generally stay there for the first part of their lives, occasionally moving upriver when there is an increase in salinity. The exception is the largetooth sawfish where the young move upriver into freshwater where they stay for 3–5 years, sometimes as much as from the sea. In at least the smalltooth sawfish the young show a degree of site fidelity, generally staying in the same fairly small area in the first part of their lives. In the green and dwarf sawfish there are indications that both sexes remain in the same overall region throughout their lives with little mixing between the subpopulations. In the largetooth sawfish the males appear to move more freely between the subpopulations, while mothers return to the region where they were born to give birth to their own young.
Sawfish
Although fishing is the main cause of the drastic decline in sawfish, another serious problem is habitat destruction. Coastal and estuarine habitats, including mangrove and seagrass meadows, are often degraded by human developments and pollution, and these are important habitats for sawfish, especially their young. In a study of juvenile sawfish in Western Australia's Fitzroy River about 60% had bite marks from bull sharks or crocodiles. Changes to river flows, such as by dams, can increase the risk faced by sawfish young by bringing them into more contact with predators.