For NOAA Scientists, Tagging Yields Clues to Endangered Sawfish

John Carlson and Jennifer Schull
NOAA’s Southeast Fisheries Science Center

August 20, 2009 — Working with sawfish can be grueling.

If you can avoid their toothed, saw-like snouts while handling the animals, that’s all the better. But, you still have to deal with dense mangroves, rocky oyster beds, and a whole lot of mosquitoes that share their shallow-water habitats.

This obstacle course of sorts fails to deter scientists from NOAA’s Southeast Fisheries Science Center (SEFSC) who are seeking to understand and recover populations of this unique and misunderstood creature. They are used to trudging through difficult terrain to deploy a variety of sampling gear aimed at tagging and studying sawfish in their natural habitat.

Sawfish, like sharks, skates and rays, belong to a group of fish called elasmobranchs whose skeletons are made of cartilage. Sawfish are actually modified rays with a shark-like body and gill slits on their underside.

Protected since 2003 under the Endangered Species Act, smalltooth sawfish (Pristis pectinata) were once common in the Gulf of Mexico and the southeastern United States. Decades of recreational and commercial fishing pressure and loss of habitat conspired to nearly wipe out this charismatic ray, and now they are found primarily in southern Florida. Their known nursery habitat is in the wild maze of lush mangrove forests of the Ten Thousand Islands and Everglades National Park.

“Conditions can be somewhat arduous and you continually have to monitor the tide and wind, or you may end up with your boat stuck on a mudflat,” says Dana Bethea, SEFSC Research Ecologist. Despite the difficulties, researchers are finding some surprising results.

Juvenile sawfish are, in fact, highly site-specific. They may return not only to the same estuarine habitat, but also to the same specific mangrove forest where they grew up. Mitochondrial DNA identification of recaptured sawfish, conducted by NOAA in collaboration with university geneticists, has revealed that sawfish siblings may occupy the same mudflat and that a single adult female may give birth on that same mudflat year after year. Researchers are also using state-of-the-art satellite tags and smart position and temperature tags (SPOT) to keep track of sawfish as they go about their daily activities

Information from tagging studies like these helps the Smalltooth Sawfish Implementation Team — a multiagency team from NOAA, state agencies, universities and non-governmental organizations — execute the Smalltooth Sawfish Recovery Plan in U.S. waters. Domestic and cooperative international research, coupled with policy decisions, such as the 2007 prohibition on international trade of smalltooth sawfish via the Convention on the International Trade in Endangered Species (CITES), are helping to bring the smalltooth sawfish back from the edge of extinction.