The SDRP is unique because the team has been conducting health assessments on wild dolphins since the 1980s. This provides benchmark data for the protection of dolphins worldwide.
This information is important. We need to better understand how to heal sick or injured wild dolphins, and to interpret health data from other dolphin populations where, for example, oil spills or unusual mortality events have occurred.
The purposes of the Health Assessment program are:
- to mark and collect samples from dolphins who have never been captured before.
- to continue our studies of how environmental contaminants impact dolphin health and reproduction.
- to compile baseline data on what constitutes “normal” health for wild bottlenose dolphins.
Data and samples supported 29 different research projects
During a health assessment, a dolphin is examined by a team of veterinarians and scientists, and then it is released. In 2009, data and samples from dolphin health assessments supported 29 different research projects in the areas of dolphin health, environmental contaminants, bio-toxins, life history, population structure, ecology, hearing, and communication.
What is a health assessment?
Dolphins selected for health assessments are lifted into the exam-boat, placed onto soft pads, and given a thorough health exam by the team of veterinarians and scientists.
All the while, the dolphin is monitored by team members, who keep the patient calm, wet, and comfortable.
The exam starts with weighing and then measurements. This is no small task since an adult Sarasota dolphins can weigh over 600 pounds and measure more than 8 feet long. We take 32 measurements, called morphometrics, so we can learn how wild dolphins grow as they mature.
Usually, data for multiple studies are conducted simultaneously. For instance, while the dolphin is being measured, the dolphin’s sounds are monitored constantly with a hydrophone (like a water proof microphone), and samples or data may be collected that doesn’t interfere with other activities.
Blood is taken by one of the veterinarians from a blood vessel in the tail flukes. Some of the blood is later processed in our lab, and some is sent off for special processing.
Samples are shared with other scientists and research veterinarians. Some blood samples are used to measure levels of environmental contaminants in dolphins.
After the health assessment, the dolphin is released back into the wild.
Health Assessment Results
Over the decades, results from our dolphin health assessments given veterinarians and conservationist a unique look at the biology of wild dolphins.
What we learn helps veterinarians to treat sick dolphins.
Sarasota is the only place where the health of wild dolphins has been monitored for generations. This is important because what we learn helps veterinarians to treat sick dolphins who strand in the wild, and to keep captive dolphins healthy.
More importantly, what we learn helps us understand the source and nature of health threats to dolphin populations elsewhere.
The health assessments are valuable both to dolphins and marine mammal professionals.
- We help veterinarians and field biologists learn or perfect techniques for safely working with dolphins in the wild.
- We provide unique opportunities for scientist to conduct experiments on wild dolphin communication, and to test technology designed for use in wild dolphin research.
Below are some of the findings from our health checkups:
We know little about viral diseases in dolphins. Our collaborators are developing state-of-the-art molecular tools to detect viruses and study their impact on marine mammals.
Prior to 2003, only 11 virus species had been reported in all marine mammal species combined. Just in the last three years, calaborating scientists have identified 10 previously unidentified virus species in our dolphins.
This research also has confirmed that humans in close contact with dolphins can be exposed to dolphin viruses and dolphins can catch a virus from humans.
This research was supported by Marine Animal Disease Lab at the University of Florida, and by the Chicago Zoological Society.
Lungworms, are parasites commonly found in the respiratory systems of stranded or dead dolphins. But we know little about how often these parasites occur in healthy wild dolphins, and whether lungworms might be transmitted from mother to calf.
To study this problem, veterinarians collected swabs from dolphin blowholes and samples from their feces. So far, the early evidence suggests the occurrence in wild dolphins is low (only 3%).
It appears that lungworm infections may be transmitted from mother to calf during pregnancy. The impact that such infections may have on calf survival before birth is unknown, but these infections could increase mortality of newborn dolphin calves.
This research was funded by Harbor Branch Oceanographic Institution and supported by the Chicago Zoological Society.
We tend to think of plankton-rich waters as a sign of a productive habitat and as good feeding grounds for whales. But some types of plankton can become a problem for marine animals (and humans nearby) if the plankton population explodes.
When this happens in the Sarasota area, it’s called a red tide. The ocean sometimes has a reddish-brown tint because of all the plankton in the water. The plankton causing red tide is called Karenia brevis. The plankton produces a suite of harmful toxins, called brevetoxins, that can build up in fish and cause massive fish kills. Brevetoxins can build up in dolphins that eat the fish, or dolphins can inhale the brevetoxins that occur in the air just above the water’s surface. Brevetoxins also impact manatees, sea birds, and sea turtles.
Most (76%) of the 21 dolphins stranding in Southwest Florida during 2006-2007 had brevetoxin levels high enough to be detected. In almost one third of these, brevetoxin poisoning was implicated in the animal’s death.
This research was supported by funding from the John H. Prescott Grant Program, Morris Animal Foundation, the Florida Sea Turtle License Plate Sea Turtle Grants Program, and the Chicago Zoological Society.
Antibodies are found in blood or other bodily fluids, and they help the immune system identify and neutralize harmful bacteria and viruses. But little is known about the immune system, or immunology, of dolphins.
Understanding dolphin immunology is critical in the diagnosis, treatment, and management of diseases in captive dolphins, and it’s vital to help nurse sick wild dolphins back to health if they strand. Understanding a dolphin’s immune system helps a veterinarian evaluate the effects of age, infectious diseases, and exposure to toxins.
Because captive dolphins are fed frozen-and-thawed fish and are routinely treated with anti-parasite medications, it is wise to have information for comparison from wild dolphins that likely carry higher parasitic loads.
Funding for this project was provided by Merck Merial Veterinary Scholars, and it was supported by the Chicago Zoological Society.
Milk and solid food for dolphin calves
Calves stay with their mothers for 3-6 years, and they may continue to nurse during much of this time.Research conducted from 1988 to 2006 looked at the nutritional value of milk received by dolphin calves, and when calves start catching fish for themselves.
Results show that calf body weight increased with the percentage of milk fat, and varied inversely with milk water and potassium content in their mother’s milk. There was no significant link between calf survivorship and milk composition.
Blood values from moms and calves caught together suggest that mothers don’t leave their calves to forage for food. If the mother is eating a large meal, the calf is also likely to be ingesting a lot of food.
These results suggest that while continuing to nurse from their mothers at least occasionally, dolphin calves are gradually learning to catch more and more food for themselves. They probably learn about foraging grounds and prey capture techniques from their mothers.
A dolphin and human disease
Dive Deeper into the science of dolphin skin disease:
Lobo’s Disease [Lacaziosis (Lacazia loboi)] occurs naturally only in humans and dolphins. It is a chronic and slow-growing skin disease. It was first observed in dolphins by Randy Wells and Blair Irvinein 1970.
This new research is using health assessment data to estimate the prevalence of Lobo’s disease in the Sarasota Bey and Charlotte Harbor dolphin communities.
Graduate student Leslie Burdett Hart is comparing the progression of the disease among four Sarasota Bay resident dolphins that have it, using long-term photographic data. The influence of how genetic, social, and environmental factors that may affect disease progression will also be studied
Funding for this project was provided by NOAA’s Center of Excellence for Oceans and Human Health, Hollings Marine Laboratory, and the Chicago Zoological Society.
All photos © Sarasota Dolphin Research Program under NMFS permit #522-1785