Dolphin Studies Range Far and Wide
By: Nadine Slimak
“Oh, give me a home where the buffalo roam
Where the deer and the antelope play
Where seldom is heard a discouraging word
And the skies are not cloudy all day
Home, home on the range
Where the deer and the antelope play
Where seldom is heard a discouraging word
And the skies are not cloudy all day”
—Brewster Higley
Thanks to “Home on the Range” author Brewster Higley we know where the buffalo roam and the deer and the antelope play. But until the Sarasota Dolphin Research Program came along in the 1970s, where dolphins roamed, played and, in essence, made their living was still a mystery.
“No one really knew much of anything about ranging patterns and we didn’t really have any knowledge of what the word ‘population’ meant for dolphins,” said Dr. Randy Wells, manager of the Sarasota Dolphin Research Program, a joint program of Mote Marine Laboratory and the Chicago Zoological Society/Brookfield Zoo. “Before you can provide the appropriate protection measures, you really need to know what you’re working with.”
Mote pioneered field studies of dolphins — learning how to safely handle, tag and release them — in order to understand more about populations and ranging patterns. After the passage of the Marine Mammal Protection Act, that information was given to resource managers tasked with weighing threats to dolphins and creating appropriate responses. Today, not only is the information being used to protect wild dolphins, but it’s also being used as a model in other countries whose research is much younger.
“One key element of the Sarasota Dolphin Research Program is that scientists from all over the world come here to train with us and learn about our techniques so they can apply them to dolphin conservation research — often involving endangered dolphin species — in their own countries,” Wells said.
Training: 2006
Sarasota Bay studies today go beyond just tagging operations. They include regular check-ups that scientists use to keep tabs on the health of the dolphin population. The information gathered is also used as a medical reference for assessing other dolphin populations. Researchers from places as far away as China and Pakistan come to Mote to learn new techniques that they can take home to their colleagues.
“We initially used tags to identify individuals and re-sight them,” Wells said. “Then, in the mid-1970’s, we learned that we could use the animal’s own natural fin features to distinguish individuals. With the advent of miniaturized electronics, we began testing radio-tags that we could use to monitor dolphin movements day or night, and then satellite-linked tags that we can use to track them remotely. It’s really great to be able to share these approaches to help fledgling programs in other places.”
The tagging work initiated in 1970 led researchers to discover that the dolphins in Sarasota Bay were residents that lived there year ’round — the first such finding in the world. That work eventually shifted to more in-depth studies looking at the health and well-being of the bay’s animals and the factors that affect the population.
In 2006, 110 scientists, veterinarians, graduate students, dolphin handlers and staff from other zoos and aquariums met at Mote to participate in more than 25 research studies involving Sarasota’s dolphins. During five days of field work, the carefully choreographed team briefly handled 20 dolphins to gather information about the physical characteristics of the animals — including age, genetic make-up, contaminant levels, immunological condition — as well as information about their senses, for instance, how dolphins use clicks and whistles to communicate with each other and navigate their environment and how well they can hear.
“We needed to be more proactive to really understand the health threats to dolphins, especially if there are things humans are doing that affect their lives or the habitat in which they live,” Wells said. “So we expanded our operations in 1987 to include more than just tagging.
“Of particular interest in 2006 was the possibility of measuring the effects of the prolonged and severe 2005 red tide. The calves we measured were significantly smaller than calves of the same age previously measured, and we noted that their mothers and adult males also weighed less than expected. That would be consistent with the findings of our purse-seining team investigating the availability of prey fish. Under Dr. Damon Gannon’s direction, the team noted a reduction in prey caused by the red tide.”
The 2006 effort included researchers from Argentina, Australia, Canada, China, Denmark, England, Germany, Guatemala, Scotland and Tasmania. Argentine biologist Pablo Bordino is one researcher who came to Sarasota to learn more about dolphin handling and release operations for tagging. Bordino has been studying franciscana dolphins (Pontoporia blainvillei) since 1992. Those studies are now the flagship program of AquaMarina Centre for Marine Sciences, which Bordino created in 1999 to further marine research and education efforts in Argentina.
Bordino and nearly a dozen of his crew members have traveled to Sarasota regularly since 2003 to learn more about wild dolphin studies here so that they might use the information to help protect one of the world’s smallest and most endangered dolphin species. “Randy is one of the most famous scientists — everyone knows his work,” Bordino said. “While I was at the university in Buenos Aires, I would read books and papers by Randy and learn about his work. I wanted to create a project like Randy’s in Argentina.”
Tagging: 2007
Franciscana dolphins — also known as La Plata River dolphins — are native to the coastal waters of Argentina, Uruguay and Brazil. They’re small — adults are roughly 5 feet long and 100 to 120 pounds — and usually travel in small groups, up to three to five animals.
“The main threat they face is incidental mortality in fishing nets,” Bordino said. “There are an estimated 35,000 animals in Argentina and about 1,000 per year die in gill nets. That’s 2.8 percent of the population. The other problem is that about 70 percent of the animals entangled are females, with many of them pregnant. We really need to work on this problem.”
To understand how the franciscana dolphins are affected by fishing and other issues such as habitat degradation and fragmentation, Bordino needed more information about the dolphins themselves. Were the dolphins living off Argentina’s coast one large group or several smaller units? What areas did they frequent, and where did they travel? What was their genetic makeup?
“For years, we only had information from deceased animals,” Bordino said. “It’s so different to see dolphins in the wild.”
Bordino faced some hurdles in his quest for information.
Franciscana dolphins are small, their dorsal fins are only a few inches tall, and most don’t have distinctive markings like Sarasota Bay’s bottlenose population.
The waters where Bordino works tend to be choppy, and the small dorsal fins aren’t easy to spot in the waves. The dolphins also don’t make much noise when they surface to breathe — there’s no real “chuff” sound like that made by bottlenose dolphins. Franciscana dolphins also live in murky estuarine water, and their coloration makes them hard to spot when they do surface.
That meant the only way to really understand what was happening was to tag them with radio transmitters and release them. “The problem was no one had any experience catching dolphins,” Bordino said.
But Wells, with more than 30 years of capture-release and tagging experience under his belt, knew how to safely work with dolphins in the wild. The result? A collaboration that led to the first radio and satellite tagging of wild franciscana dolphins.
In 2005, Wells took a team to Bahia Samborombon, near San Clemente del Tuyú , Argentina, to help Bordino and his crew of 40 tag three dolphins with tiny short-range radio transmitters and follow their movements. The Argentinian-American team returned to the same area in 2006 and in 2007 traveled to Bahia San Blas, farther south and close to the southern extent of the species range. The findings could prove crucial to saving the La Plata dolphins; information gathered over the past three years has already led to new insights on the travel patterns of franciscana dolphins.
“Before this research, everyone thought that the franciscana dolphins of Argentina were one large population,” Wells said. “Our findings suggest this species lives in fairly discrete, localized populations. Genetic studies help support this idea for Bahia Samborombon. While we have to wait and see what new information we can glean from this most recent round of satellite tagging, our first two weeks of tracking data suggest that franciscana dolphins tend to be local residents of Bahia San Blas as well. These findings have certain implications for management decisions.
“Are the populations of dolphins in Bahia Samborombon and Bahia San Blas anomalies, or do they represent a different ranging pattern than that proposed by wildlife management agencies? Protection of local populations — where we can identify exposure to specific threats — can be approached differently from the way widely ranging populations are managed.”
For Bordino, the question is more than academic: It has become his life’s work. “Usually I want to be involved in big challenges, and this dolphin has a big challenge.”
Research in Argentina has been supported by
Wildlife Trust,
Disney’s Animal Programs,
the Chicago Zoological Society,
the Chicago Board of Trade,
and Bill Scott.
Learn more about: Dolphin Research
Go Back | Send this page to a friend |
Mote Marine Laboratory has been a leader in marine research since it was founded in 1955. Today, we incorporate public outreach as a key part of our mission. Mote is an independent nonprofit organization and has seven centers for marine research, the public Mote Aquarium and an Education Division specializing in public programs for all ages.
