Search For Sawfish Centers Here

May 12, 2006

Release from: Kevin Lollar
The News-Press (Southwest Florida)

As the research vessel inched along the gill net in the clear, pond-calm water of Glover Bight near the mouth of the Caloosahatchee earlier this week, an unmistakable shape came into view.

"We have a sawfish," said Beau Yeiser, a staff biologist at Mote Marine Laboratory. "This is a little guy. Female. No tag."

Time for Mote's sawfish research team — Yeiser, senior scientist Colin Simpfendorfer and intern Krystle Harvey — to get busy.

A few feet farther down the net, a second sawfish.

Led by Simpfendorfer, Mote scientists have been studying smalltooth sawfish, a shark-like ray, in the Caloosahatchee River and Ten Thousand Islands since 1999. A goal is to determine how many sawfish are in Southwest Florida's waters.

Mote's team fishes the Caloosahatchee and Ten Thousand Islands three to five times a month. Along with the Florida Fish and Wildlife Conservation Commission, Mote has tagged about 100 sawfish, 25 in the Caloosahatchee.

Smalltooth sawfish, listed as an endangered species in 2003, once ranged from New York to Texas, but the U.S. population is now restricted to Southwest Florida. Some scientists estimate the population at 2,000.

"How many there are, we have no idea," Simpfendorfer said. "That's one of the things we're trying to document."

One reason for the sawfish population crash is overfishing.

Recreational fishermen used to cut off sawfish saws for souvenirs.

Although sawfish were never targeted by commercial fishermen, many were killed when they were caught in commercial gill nets.

Fishing pressure is no longer a major issue for sawfish. Even before they were put on the Endangered Species List, sawfish were protected in Florida, and the use of gill nets in state waters became illegal in 1995.

The other reason for the crash was, and continues to be, loss of habitat. Southwest Florida has the best remaining sawfish habitat.

First stop for the sawfish team was the narrow, shallow eastern end of Glover Bight, almost in the shadow of the high-rise condos of Cape Harbour. Across the mouth of the mangrove-lined narrows is a sand bar only a few inches deep at low tide.

Among other things, the Mote team is trying to identify important sawfish nurseries.

"It has everything sawfish love," Simpfendorfer said. "It's shallow .... It has shoreline vegetation, and the bar at the opening protects it from predators like bull sharks."

Inside the area, the scientists set two 200-foot gill nets.

They attach an acoustic tag to every sawfish they catch, so while the nets were soaking, Veiser used a receiver to listen for other tagged fish.

Acoustic signals on sawfish and tagged sharks also can be picked up by receivers up river to W.B. Franklin Lock.

After checking for pings, the scientists checked the nets.

First net, empty.

A second net, two small sawfish, a male and female, the teeth of their saws tightly tangled in the mesh. Yeiser and Harvey removed the fish.

With Harvey holding the male fish over the side of the boat, Yeiser and Simpfendorfer took measurements of the female: weight 5.5 pounds; saw length 9.2 inches; total length 39 inches.

Next, the scientists attached external and acoustic tags to the dorsal fin. Then, they inserted a transponder tag under the skin. The tag is like a bar code that can be read with a receiver.

Finally, Simpfendorfer clipped a small piece of the dorsal fin for genetic analysis.

The scientists repeated the process on the second fish.

When all tags were attached and measurements taken, the fish were released.

All five sawfish caught in a span of two days were juveniles, indicating that Glover Bight vital.

"We might be able to preserve small amounts of important habitat even in crowded areas and support a good number of sawfish," Simpfendorfer said.

From Glover Bight, the team crossed the river to the sawfish hot spots Iona Cove and then Peppertree Point.

No luck at either place.

Despite only catching two sawfish in eight hours, the day was a success: Data from the two animals will become part of the project's database and can be used to understand the species and help it recover.

But why bother?

"Every part of the ecosystem is important," Simpfendorfer said. "If you take out the big predators, it will have effects. If you take away the algae eaters, it will have effects. Sawfish are an important component, and keeping them keeps balance in the system."