Florida’s imperiled smalltooth sawfish

Smalltooth sawfish

Last October, I wrote a story about conservation work on the smalltooth sawfish on Florida’s Atlantic Coast, and a new “encounters database” set up to track sightings of the elusive elasmobranch. My story started out like this:

About 100 million years ago, smalltooth sawfish emerged in the planet’s oceans, teeth splayed perpendicular from a long bill projecting from where their forehead should have been. Not much has changed in their evolutionary blueprint, though the continents have swung into new positions and different currents pump through the seas…(full story)

Interestingly, the local newspaper just caught up to the story! I’m not positive of the impetus for their timing, but I’m glad they gave it some real estate.

Sawfish are amazing creatures. Unfortunately, their Atlantic populations are dwindling fast. The National Oceanic and Atmospheric Administration listed them as a distinct population segment under the Endangered Species Act in 2003. A recovery plan was drafted three years later, and it was finalized this January.

Historic distribution of smalltooth sawfish

One of the more fascinating things I learned about this species was the history of their disappearance. George Burgess, director of the Florida Program for Shark Research pulled these range maps up on his computer while I was interviewing him; I was enthralled and saddened at the same time. His maps show a clear pattern of the population’s contraction in sync with the expansion of human populations along the east coast.

Sawfish are basically large rays that evolved from sharks. The technical name for their “saw” is a “rostrum.” It’s filled with a dense network of nerves and studded with “teeth” made from a calcified cartilage material. (If damaged, their teeth will not regenerate.) They use their saw to shuffle sediment on the seafloor, rustling up small shellfish and other prey which they rapidly suck down. Or, they swing it into schools of fish to stun them and devour them. Here is a little natural history nugget from my story:

Florida Sate Archives, sawfish and small bonito shark at Key West, Fla. unknown date.

Smalltooth sawfish are a slow-growing coastal-dwelling species that were once known to range from New York to Brazil. And while nearly 2,000 historic records of sawfish exist for Florida’s waters, there are only about 175 known records from all other states.

Burgess said sawfish likely declined rapidly in the United States, in large part because they prefer shallow waters near shore and because the people fishing these throughout the 20th Century primarily used gill nets, which were disastrously effective at snaring the sawfishes’ toothy bill.

“I assume that practically every sawfish ever caught here either was killed or at least had their saws removed because they damaged fishing nets or made great curios,” Burgess said.

Smalltooth sawfish grow to about 18 feet long, and live 25 to 30 years with most reaching maturity at about 10 years old. Each litter yields between 15 to 20 embryos. They are able to tolerate a wide range of salinities — a trait known to scientists as being “euryhaline” — including salt, brackish and fresh water.

Part of Burgess’s work involves documenting the sawfish sightings of fishermen and near-shore water recreationists, as well as monitoring for the animals in Indian River Lagoon. He believes that the lagoon is a nursery for young sawfish.

The Mote Marine Laboratory is also involved in monitoring smalltooth sawfish on Florida’s southwest coast. The population there is slightly healthier than on the east coast, but only just barely so.

To learn more about this species natural history and why it is imperiled, read my full story and check out the additional resources below.

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