Sawfish are related to sharks and rays and have skeletons of cartilage rather than true bone.
■Their skin feels smooth when it is rubbed from the head toward the tail but feels like sandpaper when rubbed the other way.
■A sawfish’s saw, or rostrum, has between 22 and 32 teeth on each side and is used to kill prey and forage for food.
■Baby sawfish, called pups, grow in eggs inside the mother but are born alive with a jelly on their saws to protect the mother.
■Newborn sawfish are about 2 feet long and grow rapidly after birth. The largest sawfish usually are about 18 feet long.
■Very little is known about litter sizes, how often and when sawfish mate and give birth, but young sawfish seem to depend on shallow estuaries for protection and are loyal to certain spots.
■See a sawfish? Report it to the National Sawfish Encounter Database at the Florida Museum of Natural History (www.flmnh.ufl.edu/fish/sharks/sawfish) by calling 352-392-2360 or by email to email@example.com.
Source: Mote Marine Laboratory, Florida Museum of Natural History
CHOKOLOSKEE _ By mid-afternoon, exhilaration had turned to exhaustion for a research team hunting endangered smalltooth sawfish and looking for answers in the murky shallows of Chokoloskee Bay in Everglades National Park.
The National Oceanic and Atmospheric Administration has teamed up with Florida State University for the past two years on a sawfish abundance study and tag-and-track project that is slowly piecing together the mysterious lives of the first marine fish to get a spot on the federal endangered species list in 2003.
On a Saturday in late October, the four-person crew had been afloat since sunrise, setting nets and pulling them in, capturing 17 of the elusive creatures — shattering the size of the team's previous monthly hauls, which they usually can count on one hand.
"That was crazy!" NOAA research ecologist Dana Bethea said as she piloted the team's boat after the last net had been stowed. "I was not expecting that. Pretty wild."
Every month from March to October, the team piles into a huge Ford pickup for the trip from NOAA's marine research lab in Panama City for a week's stay in Everglades City to capture juvenile sawfish, tag and measure them, track them, draw blood for hormone analysis and snip a fin sample for genetic testing. Besides Chokoloskee Bay, the Faka Union canal and Goodland are target spots.
The work is immersive. Crew members say they dream in their sleep about catching sawfish only to have them disintegrate in their hands. In their waking hours, they have become quasi-celebrities to locals who swap sawfish stories with them at the dock or quiz them at local hangouts about the latest study developments.
"I think most people know who they are," said Patty Huff, publisher and co-editor of The Mullet Rapper in Everglades City. "I think it's good people see them out there trying to help our waters."
They research crew drops its 21-foot Trancat into the water at Outdoor Resorts in Chokoloskee. The R/V Pristis, a reference to the scientific name for sawfish, is loaded with gear and coolers. From the docks, it's a short trip to the other side of the island to set their nets — two 100-foot nets and two 200-foot nets — along the mangrove-lined shore on the west side of State Road 29.
After the fourth net is stretched from shore, the crew returns to the first one to get down to business. They find the telltale dips in the top of the net that indicate where something has gotten snagged and jump in.
The first hop into the water is more of a leap of faith. The crew can't see the bottom to tell how deep it is and, on a chilly morning, can't tell how cold the water might be. It turns out to be knee deep and barely bathtub temperature.
Bethea takes samples of the muddy bottom, one to sift to look for invertebrates and the second to analyze for sediment type as researchers try to figure out what makes sawfish favor some spots over others.
The crew gets a good grip on the sawfish to keep it from slashing around while they cut its saw, called a rostrum, from the mesh. They sink into the mud, wondering aloud what they are stepping on. Rogue waves throw them off-balance. Protective footwear keeps them from slicing their soles on oyster shells, and heavy-duty gloves keep them from cutting their hands.
Besides staying away from the sawfish's razor-toothed saw, tops on the crew members' minds is not dropping the precious catch before they can tag it, record measurements and take samples.
"That's my biggest fear," said Kelcee Smith, a lab technician at the Panama City shark assessment program.
They work carefully, hunched over the sawfish, or hanging over the edge of the boat. They count the number of teeth on either side of the saw and call out the numbers for Bethea to record on a data sheet along with various length measurements.
On a count of three, the sawfish holders turn it on its back to get a blood sample from its underside and synchronize their timing when they lift the fish out of the water only long enough to put it on a measuring board. Otherwise, they keep the sawfish submerged so it can move water across its gills to breathe.
A sliver of fin is dropped into a vial filled with ethanol. The vial is kept in a numbered plastic bag with the same fish's blood sample and stored in an ice-filled cooler. Used syringes are discarded into a recycled parmesan cheese container.
Bethea reaches into another parmesan cheese can to get one of the yellow tags that will poke out of the side of the fish with a phone number that fishermen can call to report catching it. Each fish also gets a tag inserted under its skin that can be scanned to identify the fish.
Some sawfish get a third tag attached to their first dorsal fin. The tag emits a signal that an array of 32 acoustic receivers picks up as the fish swims past, recording the tag number and giving researchers an underwater glimpse into where the fish go.
Data are downloaded monthly from the receivers, which are taped to a PVC pipe cemented into a cinderblock and lowered into the shallow waters around Chokoloskee.
The researchers don't always wait for the fish to come to them: Florida State University graduate student Lisa Hollensead also uses the radio signals from the tag to go find them and follow sawfish around in real time to learn more details about their habits.
Each tag emits an ultrasonic ping at a unique radio frequency every two seconds. Hollensead uses a hydrophone to pick up the signal and can tell where the sawfish is going by whether the signal is getting stronger or softer. She paddles a kayak to keep from disturbing the fish's natural movements. One fish is a favorite of hers.
"I named him Charlie because I never met a Charlie I didn't like," she said.
Charlie was first tagged at Faka Union in August 2010. That tag dropped off the fish, which was recaught and retagged last October. The same fish was caught again this September and fitted with a new tag. In October, Charlie was tracked continuously for 32 hours, a tedious but valuable encounter, Hollensead said.
She has learned that sawfish, especially young ones, don't move around much. She has picked up the signal from the same fish at the same spot for days in a row. Like clockwork, about two hours before high tide, one sawfish she tracked would start moving toward spots where the water will stay shallow. She appreciated being able to get a head start, she said.
"It sometimes can be difficult keeping up with them in a kayak," Hollensead said.
In 2010, the team caught six sawfish and tagged five of them with acoustic tags, a disappointing number that Bethea blamed in part on last year's cold snap. Fishing has been better in 2011, with 29 sawfish caught and 10 tagged with acoustic tags. They plan on being back in 2012.
"We're learning more about them every year," said NOAA fishery biologist John Carlson, at the Panama City lab. "We're finding out stuff that we never thought we'd find out."
They've learned that sawfish grow fast, about 4 inches a month after birth, longer than researchers thought, Carlson said.
Researchers work from March, about the time they think sawfish are born, to the end of October, when they thought the sawfish moved out of the area. The size and quantity of the sawfish caught this month has them rethinking that theory.
As the catch tally climbed last week, the crew grew increasingly amazed — and worn out — as they pulled the boat up to the last net of the day."I'd like to get one more," shark program intern Joshua Boston said.
That would have made it an even dozen, doubling in one day the number of fish the team caught all last year. The last net turned out to hold not just one sawfish, but six.
By 3 p.m., the last sawfish had been tagged, measured and released. The nets were stowed back in their blue bins.
Bethea steers past mangrove trees towering over a feeding roseate spoonbill and basking alligators. The other three crew members lay on their backs on the front deck, looking skyward and talking about what they'll fix for dinner.
Back on land, they stop at a gas station for stone crab claws and eat them with shrimp and Andouille sausage jambalaya.