Ever wondered where dolphins “go” when they are swimming around? Well, a new Tracking button on the home page (below right) and in What We Do will help to satisfy your curiosity. You’ll learn about why we tag some dolphins with satellite-linked transmitters, and you can look at some of the recent movements of tagged animals. As you’ll see, some of their movements overlap, but they often hang out in different places. Oh, by the way, resident bottlenose dolphins in the Sarasota Bay area are constantly on the move, swimming about 2-4 mph on average.
Archives for June 2012
We know the ages of most of the bottlenose dolphins in the Sarasota population.
Knowing the age distribution of a population is critical for conservationist.
Age can help us understand if the population is healthy or not, and whether it is likely to increase or decrease in the future.
Also, age is a crucial measure for determining how environmental contaminants accumulate over time in dolphins.
But how do we learn their ages? Often, we know it because we have observed new calves since our study began in 1970, and we’ve watched them grow up.
If we don’t know when a dolphin was born, we can estimate age by looking at one of its
100 or so teeth. This involves removal of a tooth under local anesthesia by a trained marine mammal veterinarian. Over the years, we have found this to be a simple and safe procedure.
This method has allowed us to estimate that Nicklo was 64 years of age in June 2014, and is the oldest documented bottlenose dolphin to date. A very few males, like Jimmy Durante, reach 50 years of age, and F154 was 51 years of age in June 2014.
An expert, such as Dr. Aleta Hohn of the National Marine Fisheries Service, prepares the tooth and carefully examines the dentine and cement through a microscope. Like the growth rings in trees, dolphin teeth have annual layers called “growth layer groups.” Annual layers are added from the outside in, gradually filling up the cavity in the middle of the tooth. The layers can be counted to estimate age. This technique was refined and validated with SDRP dolphins and is now used world-wide to estimate dolphin age.
16 Sarasota Bay dolphins, including 4 for the first-time, were captured, examined by veterinarians, and released during May 16-20, 2012. Data from this work will be shared across more than 25 projects, among researchers from national and international universities and federal and state agencies.
Preliminary results from veterinary examinations and sample analyses suggest that the dolphins generally are in good condition. They appear to be in better health than those dolphins sampled in Barataria Bay, Louisiana, in August 2011.
The health of the Sarasota Bay dolphin population is a benchmark against which to compare effects on bottlenose dolphins of large-scale environmental events, such as the 2010 Deep Water Horizon oil spill in Louisana, environmental pollution from industrial sites, or harmful algal blooms.
Nellie was fully examined for the first time, and she was found to be in good health and body condition. In 2010, as a 9-month-old calf, she was rescued and disentangled from life-threatening line.
Perry, a 23-year-old male, weighed 660 lbs (300 kg, 2 kg less than his 2010 weight record for a Sarasota dolphin), and his 19-year-old male alliance partner Pednotches, weighed in at 422 lbs (192 kg). These males had the highest testosterone concentrations of any adult males measured this summer. They were on a “date” with 16-year-old Lizzie (and her 2-year-old son), and have been seen with a variety of presumed receptive females since their release.
As part of research to determine the potential impact of new and improved electronic tags on dolphins, 10 dolphins were tagged with real or “dummy” satellite-linked transmitters. These dolphins are being closely monitored, and we plan to re-capture them in several months to remove the tags and evaluate the condition of both tags and dolphins. The new tag design resulted from computational flow dynamics research that determined how best to reduce drag.
The health assessment team totaled 110 researchers, veterinarians, students, and dolphin handlers, with as many as 80 participating each day.
They came from as far away as Brazil, Canada, Australia, Malaysia, South Korea, Scotland, England, Spain, Germany, Denmark, Guatemala, and Trinidad/Tobago. Most of our foreign colleagues were learning about techniques to take back for conservation work in their home country.
A total of 19 veterinarians cycled though during the health assessments from multiple universities, agencies, and organizations.
The health assessments were primarily funded by Dolphin Quest, and the Office of Naval Research, and they were conducted under a scientific research permit from the National Marine Fisheries Service.
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