Smalltooth Sawfish Research in the Florida Keys
Written by Bethan Gillett; photos by Emily Warchol
The smalltooth sawfish (Pristis pectinata) is an endangered marine species, closely related to guitar fish. The waters off South Florida are one of the last habitats where these remarkable creatures still thrive. Florida Program for Shark Research and Florida State University's Marine Ecology Lab collaborate to learn more about sawfish behavior, ecology, and life history. As with many rare and endangered species, one of the biggest obstacles for those attempting to study sawfish is finding them. This month's sampling off the Southwestern coast of Florida has been one of our most successful efforts, resulting in the capture and release of nine adult sawfish.
The team spent four days aboard "Whips N' Fins", a commercial shark long-lining vessel based in Key West. We set out just after day break, chopping ladyfish and baiting hooks as we moved westward towards the Marquesas. The weather was perfect to be out on the water; partly cloudy skies with calm glassy seas. Each day's fishing consisted of 6 lines, each equipped with 100 hooks, over a distance of one mile. Soaking two lines at a time for a one hour period gives us a decent catch rate, without compromising the animals' release condition.
Our catch consisted mostly of nurse (Ginglymostoma cirratum) blacknose (Carcharhinus acronotus), sharpnose (Rhizoprionodon terraenovae), and blacktip sharks (Carcharhinus limbatus); all common species in Florida waters. Caribbean reef (Carcharhinus perezi) and great hammerhead (Sphyrna mokarran), and bull sharks (Carcharhinus leucas) were also among the catch. There was absolutely no teleost bycatch. Once aboard, we measure, tissue sample, photograph, and dart tag all sharks, working quickly to release them alive.
The best aspect of fishing is never knowing exactly what will be caught on the line resting hundreds of meters below. The deck bustles with exhilaration as the distinctive sawfish silhouette floats up slowly towards the side of our vessel. The sawfish ranged in size from 10-14 ft long. This size class is thought to be mature, although sawfish have been known to reach lengths of up to 25 ft.
We equipped each sawfish with a high-tech satellite tag, tethered to an umbrella dart, which anchors it in the base of the dorsal fin. After several months of recording, these tags will pop off and transmit temperature, depth, and location data to a satellite. Analysis of blood, DNA, and tissue samples gives us further clues into the life history and ecology of this little known fish. Our goal is that our efforts will bring about an improved understanding of sawfish biology, with a positive influence on conservation. Thank you to all the people that continue to make this project a success. This work is conducted pursuant to Endangered Species Permit #13330.