In January 2009, NOAA fisheries published the final plan for recovery of the endangered smalltooth sawfish (Pristis pectinata). This fascinating animal lived, at one time, from Brazil to New York, and throughout the Caribbean and Gulf of Mexico.
An elasmobranch, it is related to sharks, skates and rays, and looks like a cross between a skate and a shark, with a snout that is equipped with a long two-bladed saw fitted with rostral teeth along each edge. It is a long-lived and very slow growing animal that produces few young. These factors, combined with its slow-moving nature and tendency to get tangled in every sort of fishing gear and marine debris, make this animal extremely susceptible to population depletion.
From the first records in the 1830s and for the next 100 years, smalltooth sawfish were common in the warmer coastal U.S. waters. Population concentrations occurred on both coasts of Florida, with common reports from the mid-Atlantic coast during the summer. It is thought that these fish may have been seasonal migrants from Florida. In the northern Gulf of Mexico, smalltooth sawfish were most common during summer, but the presence of small specimens and presence in winter may have indicated a reproducing, resident population.
Like all elasmobranchs, sawfish utilize internal fertilization, but surprisingly little is known about other aspects of reproduction in this species. Sawfish are thought to be ovoviviparous, which refers to development within an egg within the female, and hatching just before birth. The long toothed rostrum is very flexible in the embryo, and there is a membranous sheath covering the rostrum until just after birth. Litter size is unknown, but may be as small as 5-10. The youngest sawfish live in very shallow waters; a few inches deep. It is thought that this helps them avoid predation by sharks. Exposure to predation by birds in shallow water may not be a problem with sawfish, as the possession of a toothed rostrum nearly as long as their bodies would make them poor choice of a meal for a predator that swallows prey whole. Mangrove lagoons are a particularly important habitat for juvenile sawfish. Sawfish tend to move to deeper waters as they grow, but remain over relatively shallow sand/mud habitats throughout their lives.
Smalltooth sawfish have been considered endangered since 2000, and the largetooth sawfish (with fewer, larger rostral teeth) is considered a species of concern. Sawfish used to be a fairly common incidental catch in Louisiana; one data set showed that shrimp trawlers averaged about 40 fish per year in 1950. By the ‘60s, averages dropped to a couple of fish per year. Since 1990, only one specimen has been verified in Louisiana.
The recovery plan for this species emphasizes habitat preservation in the south Florida areas where the fish is still fairly common, with the expectation that occurrence in places like Louisiana that are outside of the core areas should also increase. Strengthening the prohibition of any killing of these fish is also specified. Sawfish have been sometimes killed for food (meat and fins), or just to get them off lines or of nets. Their rostra have also been cut off to sell as souvenirs, and have been used as ceremonial objects in Asia. It will take decades of protection to produce significant population effects with sawfish, if it is possible.
Why does the sawfish have a saw? Some early accounts describe the fish slashing at schools of baitfish in order to feed on the injured bait. Not everyone is convinced that this would be an efficient feeding strategy for the sawfish, but it would fall in line with the known uses of the rostral “bill” in the billfishes (like marlin).