Marine ecologist studying endangered sawfish

FSU biology graduate student Lisa Hollensead, measuring a juvenile sawfish in the Everglades. (Photo: Dana Bethea, NMFS Panama City)

A scientist at The Florida State University Coastal and Marine Laboratory has won a three-year, $674,989 grant to study the endangered but little-known sawfish, whose numbers are believed to have declined globally more than 90 percent.

The formidable-looking sawfish is related to the stingray but more closely resembles a shark. It has been overexploited in many parts of the world due to the commercial appeal of its prominent, toothy rostrum (snout). It also has an unlucky affinity for heavily fished tropical waters and ecologically threatened shorelines.

Marine ecologist Dean Grubbs and his Florida State team will focus their research on the ecology of the smalltooth sawfish, the only domestic marine fish currently listed in the U.S. Endangered Species Act but, until now, rarely investigated. Its once-extensive range in the United States now is primarily restricted to southwest Florida and the Florida Keys.

"Worldwide, there are only six or seven extant species of sawfishes and all are listed as Critically Endangered on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species," Grubbs said. "This means we are in danger of losing an entire order of animals that are among the largest of all fishes, including some sawfish species that reach lengths of more than 20 feet."

Grubbs said populations have declined due to overfishing and habitat loss.

"We could view sawfish as a marine analog to rhinoceros and elephants," he said. "Like the tusks of the elephant or the horns of the rhino, sawfishes have been overfished worldwide primarily for their toothed rostrum, the saw. Sawfish rostra are purchased whole as curios or even powdered for medicinal use and can bring several thousand dollars.

"Their 'saw' also makes these fishes highly susceptible to bycatch in many fishing gears," Grubbs said. "In addition, they depend on habitats such as mangrove-fringed shorelines that are highly sensitive to degradation from pollution and development.

"Sawfish are important upper-level predators in subtropical coastal habitats, and our ability to facilitate their recovery will be an indicator of our ability to promote and maintain healthy coastal ecosystems."

Grubbs noted that the current recovery plan for smalltooth sawfish is hindered by the general lack of information on their life history and ecology. Largely unknown is even basic information concerning seasonal residency, migration patterns and habitat affinities.

"These are the gaps that we hope to fill," he said.

In the Florida Keys, Grubbs will use sophisticated satellite transmitters in collaboration with scientists from the University of Florida to study the movements and migration of the adult fish.

In Everglades National Park, Grubbs and Florida State biology graduate student Lisa Hollensead will work with colleagues from the National Oceanic and Atmospheric Administration (NOAA) Panama City Laboratory to delineate critical habitats for juvenile sawfish by employing both passive and active acoustic telemetry — transmitters attached to the fish and listening stations to track them.

The nearly $700,000 grant to Florida State is part of $2.4 million in funding that has been awarded to the Florida Fish and Wildlife Conservation Commission (FWC) from NOAA's Protected Species Cooperative Conservation Grants Program. Grubbs will work with the FWC as a co-investigator on the sawfish study, as will researchers from UF and the Texas Parks and Wildlife Department.

In addition, Grubbs has won a nearly $15,000 grant from the National Geographic Society's Expeditions Council that he will use to lead a voyage to a remote region of the Bahamas in search of smalltooth sawfish.

"Critical to the recovery likelihood for this species is the amount of exchange or degree of isolation between U.S. and adjacent population segments," he said. "My colleagues and I will seek to use telemetry and genetics to investigate the degree of connectivity between sawfish in Florida and the Bahamas."

The Florida State University Coastal and Marine Laboratory is located on St. George Bay in St. Teresa, about 45 miles southwest of Tallahassee, in a biologically rich area that is considered one of the six biodiversity hotspots in the United States. There, Grubbs and other faculty members seek to solve the ecological problems faced by the region through science research that helps to inform policy decisions. Learn more at www.marinelab.fsu.edu.

By Libby Fairhurst