A dolphin's tale.
In the clinical way of scientists, they called her FB05.
"She was a pretty typical dolphin," says Dr. Randy Wells, manager of the Sarasota Dolphin Research Program.
That doesn't mean FB05 lived a dull life. And, after all, she was a scientific pioneer.
Wells first saw FB05 in 1971, when he participated in the pilot study that led to the renowned Sarasota Dolphin Research Program, which today is a joint program of Mote and the Chicago Zoological Society. This 40-year program is an overview of Sarasota Bay's dolphin community. "She was one of the first dolphins we identified," he says. "She was a core female of the Palma Sola female band, as we called it."
Since 1970, Mote scientists have been observing dolphins from cradle to grave and beyond. The Sarasota Dolphin Research Program works with Mote's Stranding Investigations Program, which investigates why animals strand and how they die, and the Ruth DeLynn Cetacean Osteological Collection, which catalogues the bones of dolphins and whales. Combined, these efforts illuminate the dolphins' way of life--and death.
Together, the researchers have collected information on the ordinary lives and deaths of thousands of dolphins, creating a trove of scientific data that is unmatched anywhere.
If an individual life appears unremarkable, the sum of many lives can reveal much.
In the end, FB05 was found dead on a sandbar off Longboat Key May 22, 2009. Her bones now lie in two cardboard boxes, one containing her skull and another the many ribs and vertebrae recovered after her death and necropsy (animal autopsy). The boxes are among 600 lining the walls of the cetacean bone collection at Mote, where 25-year volunteer Ruth DeLynn oversees the remains of 17 cetacean species. "You never know what you'll learn or what somebody will need to know," she says. "So we collect all possible information now, creating a reference source, a library, an encyclopedia of bones."
Wells and his predecessor, Dr. Blair Irvine, first tagged FB05 in the northern portion of the Sarasota Bay dolphins' home range, on March 18, 1971. Two months later, they spotted her again. She had lost her tag. They tagged her again. This is when some dolphins pick up a nickname. Sparks, fitted with a radio transmitter in 1975, has the Navy's nickname for a radio operator. Nicklo, the study's oldest-known female, has a nick located low on her dorsal fin and Ms. Mayhem, tagged May 1976, was memorably feisty.
FB05 was also freeze-branded (hence the "FB" designation), her skin touched with a metal number cooled in liquid nitrogen, which causes the pigment to move away and leave a visible white number on a fin. The number remained with her for life and allowed researchers to note her identity every time they saw her. And, when she died nearly 40 years after she was first tagged, it allowed them to identify her body.
FB05 is one of 1,300 dolphins tagged by Mote researchers since the program began. Even if she wasn't especially feisty or interestingly disfigured, her life was enlightening from the start, helping to establish fundamental facts of local dolphin behavior.
Before Wells' and Irvine's early pilot study, no one knew whether dolphins ranged the entire coastline or had a home ground. FB05 and the others tagged suggested it was the latter. "She and the other 11 dolphins tagged during this pilot study provided the first indications of bottlenose dolphin residency to a specific bay system, the north part of what we now know as their range," Wells says. "Our subsequent research was based on our ability to return and find them in the same area."
Over the next 38 years, Wells and his colleagues encountered FB05 862 times--sometimes just a glimpse, other times for a full health assessment that included taking her weight--as much as 450 pounds--and length--nearly 8 feet--and collecting blood, microbiology, urine, fecal and gastric samples. This was done six times between 1988 and 2001.
Mostly, the results were unremarkable. But they led to the idea of what "unremarkable"--normal--meant for dolphins in Sarasota Bay.
FB05 was found occasionally as far south as Little Sarasota Bay but mostly in the northern half of her home range, Palma Sola. Like most local dolphins, she favored inshore seagrass meadows in the summertime and wintered in the channels and passes and along the Gulf coastal waters. She also had friends--other adult females sharing her range--including Ms. Mayhem and Saida Beth.
And FB05 had at least five calves over the years, born between 1976 and 1992. Her offspring--two of whom, both females, are still living--have produced eight calves, including six that are still thriving.
FB05's life seemed relatively uneventful, and years passed with only routine sightings. But she was considered a strikingly successful mom. At one point, she was seen for several days trying to support on the water's surface a dead calf belonging to Saida Beth. When such behavior is observed, it's usually a mother supporting her own newborn, Wells says; FB05's behavior with the calf was unusual, and he still has no explanation for it.
In May 2008, FB05 moved.
She switched her home range to Roberts Bay and Little Sarasota Bay. And her clique dwindled from seven or eight to just a couple of others. Whether the move was connected to declining health isn't known, but less than a year later, in January 2009, researchers saw FB05 with raised skin lesions--a sign of infection--during a photographic identification survey. A month later, she looked skinnier, her skin was mottled and the lesions were growing and spreading. Two months after that, in May, her coloration had improved but the lesions persisted and she was still underweight.
Wells noted shark bites on her body, as if predators had noticed FB05's vulnerability. She was last seen alive on May 14. A week later her body was found.
Stranding Investigations team members are on call 24/7 to pick up sick, injured or dead dolphins from Southwest Florida. Dolphin mortality fluctuates year to year but was higher than usual in 2009, with six adult carcasses and two lost newborns found. FB05's body turned up on the bay side of Longboat Key, on a sandbar just off St. Judes Drive. Her emaciated body was put on a stretcher, hefted into me back of the Stranding Investigations Program pickup and taken to Mote. There, her remains were placed on a stainless steel table.
In most parts of the world, when a cetacean strands, those conducting the necropsy are working on a stranger. But at Mote, many of these animals have been known for decades. "It's rare to have a complete history on an animal before it gets to your table," says Gretchen Lovewell, the Program's manager. "It's more common now because of Randy's work."
Simply observing a dolphin 862 times over nearly 40 years doesn't tell you everything about its life, any more than greeting longtime neighbors at the grocery store explains their lives.
To be effective in protecting bottle-nose dolphins, Wells says, we need to understand the threats they face, and the necropsy is a valuable source of information on cause of death. In death, FB05 began to look more interesting.
Like a human autopsy, a dolphin necropsy starts with an inch-by-inch inspection of the body under bright lights. On May 22, 2009, Ruth DeLynn recorded the findings from the necropsy of FB05.
The dolphin was extremely emaciated, weighing only 178 pounds. She had a boat-propeller wound on her tail, and three shark-bite wounds and infected bite marks. Other shark wounds were fresh and probably postmortem, the result of opportunistic scavenging. Shark attacks are not uncommon, Lovewell says: 22 percent of dolphin necropsies show shark-attack wounds.
FB05 also had wounds from other dolphins. These severe "rake marks" on her skin were clearly the product of dolphin bites. "You can always tell," Lovewell says. "They're straight-line rows of marks with the teeth a centimeter apart. Dolphin bites. They go after each other. It's sexual aggression--a social thing."
The rake-mark wounds may have occurred when FB05 was young and desirable, or later when she became ill and vulnerable. The culprits tend to be young males with raging testosterone. "They may attack the weak, or attack calves with the intent of infanticide," Lovewell says. "We think males go after calves so the mothers will come back into estrus."
Understanding What Happened
The team performing the necropsy on FB05 discovered evidence of a difficult life. Most of her organs were unhealthy. She had kidney damage and her heart was extremely dense and fibrous--an old, overworked heart," Lovewell called it. There was froth in her lungs, a sign that FB05 had not died comfortably. And penetrating the right lung was a 2-inch-long stingray barb.
"You never know what you'll find," says DeLynn, with the avid curiosity of the true scientist. "It's like opening a present."
The stingray barb had been there so long that its entry wound on the skin was impossible to find.
Such barb wounds are not unknown in dolphins, and in fact are becoming more common. One issue could be that as sharks--the rays' chief predators--are fished out, there's been an increase in the stingray population. And so a dolphin in shallow water can suffer the same fate as Steve Irwin, the television naturalist, who was killed when he disturbed a stingray and it barbed him straight to the heart.
Years ago, a stingray barb penetrated the eye of another dolphin, FB0535, and eventually migrated through her body to the aorta, where it lodged and killed her. By the time the dolphin was necropsied in 2005, "half her face was missing, eaten away by infection," says DeLynn as she holds up a disfigured skull.
When FB05's necropsy was done, and all of her organs and body parts had been examined, the team summarized their results. FB05 died of multiple organ failure and old age (she was 46): emaciation, renal disease, fibrotic heart, infection and the stingray barb in her lung. But there was more to learn.
"Sometimes the soft tissues alone don't tell the entire story," Wells says. "Being able to examine the skeletal materials can tell you a great deal about old injuries or disease processes that may have impacted the animals while they were alive but was not evident from field photographs and observations, external veterinary examination, or even blood work."
When FB05's flesh was washed away, DeLynn carefully cleaned and dried the dolphin's bones. Then she laid them on a table, numbered each one with india ink and examined them--bone by bone.
To the experienced eye, bones can reveal as much as flesh and blood. FB05 had mild arthritis. Her left radius and ulna--the forearm bones in humans--were fused together. She also had a poorly healed fracture of the left scapula--cause unknown. But dolphins play rough. "Dolphins aren't these friendly little animals," DeLynn says. "They bite, they butt."
On another shelf, she points to a caved-in skull--evidently an injury inflicted on one dolphin by another. "They're wild animals.
"What surprises me is how they survive. How they keep going with all their fractures, cuts, barbs, arthritis."
Not that they have a choice, she says. "If they exhibit weakness, they'd be shark food in days."
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|Date:||Dec 15, 2010|
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