Life History and Biology

Sawfish feed on crabs, shrimps, and other bottom dwelling animals along with any locally abundant small schooling fishes such as small mullet or members of the herring family. The saw is used in obtaining food by disrupting the bottom and dislodging any prey items that may be available.

They probably also slash through schools of small fishes, stunning or lacerating them before they are consumed. Sawfish, like other bottom dwelling rays, can be opportunistic and will bite a hook or jig head baited with fresh or frozen cut or whole dead bait, live fish or shrimp, and occasionally one is caught on a lure or while fly fishing. Sawfish can also use their saw for defense, because they are tremendously powerful from side to side.

Care must be taken when handling or approaching a sawfish of any size. Although sawfish may defend themselves when they feel threatened, the only evidence of unprovoked attacks on humans by sawfish that authors know of, is an attack on a wader off the Yucatan coast, where a small sawfish (3 feet, 0.9 m) had apparently slashed at and wounded the man's legs. Other attacks on man, most or all of which were almost certainly provoked, have been documented in Panama City Bay, and one unreliable report of a fatal attack off the coast of India.

Very little is known about size, age, maturity, and reproduction of sawfish in Florida. The smalltooth sawfish has been reliably measured at a length of 18 feet 13/4 inches (5.5 meters), but may grow to over 20 feet ( 6.1 m). A 16 foot long (4.9 m) specimen weighed 700 pounds (317 kg). The size at maturity for the smalltooth sawfish is not known, but the largetooth sawfish (males and females) in Lake Nicaragua reaches maturity at about 10 feet (3 m). Sawfish have internal fertilization, such as in all sharks and rays. The eggs of the sawfish hatch in the uterus and the embryos continue to grow in the uterus without a placental connection with the mother. The embryos are nourished by yolk stored in a yolk sac, connected to the embryo by a yolk stalk and both of these structures are fully absorbed before the young sawfish are born. The gestation period of the smalltooth sawfish is not known, but the largetooth sawfish has a gestation period of about five months. Young smalltooth sawfish are probably born in late spring through summer in south Florida. Up to 20 young have been reported in a litter, and each may measure between 1.5 and 2.5 feet (0.5-0.8 m) in total length. The saw teeth of young sawfish do not fully erupt (and may also be covered in a sheath made of tissue) until after birth so as not to injure the mother, but their teeth reach their full size proportionate to the size of the saw soon after birth. The saw teeth of a sawfish are actually not teeth at all, but rather are modified scales known as dermal denticles. The reproductive cycle of the smalltooth sawfish is not known, but the largetooth sawfish has been reported to produce litters every second year. Both species grow slowly, and may not reach maturity until at least 10 years of age and may live to 30 or more years of age.

Florida's sawfish are most often found within a mile of land such as in estuaries, river mouths, bays, or inlets. They occur in a wide range of habitat types including grass flats, mud bottoms, along oyster bars, sand bottoms, artificial reefs, under or adjacent to mangrove shorelines, associated with docks, bridges, or piers. They can also be found miles up rivers in low salinity conditions. Large sawfish can occasionally be found offshore living in close association with artificial reefs or wrecks, hard bottoms, or mud bottoms.

 

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