2012 Sarasota Bay Dolphin Health Assessments

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.

Results

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.

Dolpin is lifted onto stern of RV Flip
Usually dolphins are taken aboard RV Flip, where they are examined by the research team. The boat at right is used to process blood and other samples collected from the dolphins.

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.

Dolphin monitoring goes on from above the deck.
While on board the dolphins are kept wet and cool on padded mats as they are examined by veterinarians. Above the veterinary deck, grad student Mary Gryzbek (right) records time of every breath, and all veterinary comments. Dr. Laela Sayigh (left) is listening to the suction cup hydrophones placed on each dolphin, monitoring their sounds, including whistle exchanges.

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 team

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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2011 Sarasota Bay dolphin community status

Again in 2011, for a second year, the story continues to be calves, calves and more calves.

Annie surfacing with her third calf
Annie surfacing with her third calf, less than two months old at the time. This calf is the great-great-grand-calf of Cathy (age 45), who is still alive and observed in Sarasota Bay year round. Can you imagine being a great-great-grand parent at only 45 years old?

We have followed up last summer’s 17 new babies with a very respectable eight newborns in 2011.

It has been a decade since so many calves have been born into the population over only two years.

2011 moms included three first time mothers (F165, Holly, and F199) as well as three well experienced mothers. FB25, Moonfin Look-a-like, and Tramp gave birth to their 8th, 7th, and 5th calves, respectively. In addition, Annie gave birth to her third calf this year, another in one of the two lineages we have studied across five generations. Is this calf a girl, who seven years from now will give birth to the great-great-great-grand-calf of Cathy? Only time will tell.

While it is too soon to know the long-term fates of these little guys and gals, we are happy to report that 21 of the 25 have survived to date.

Nicklo (age 61, background) and Black Tip Double Dip (58)
Nicklo (age 61, background) and Black Tip Double Dip (age 58, foreground) surface together as they head through Big Pass, probably on their way to feed in the seagrass meadow behind Mote Marine Laboratory.

The 2010 calves of FB55 and Trisha, as well as the 2011 first calf of F199 (Wanda’s 2002 calf) have not been observed with their mothers for some time and are assumed gone.

Before Trisha’s calf disappeared, it was seen with fishing line on its right tail fluke. We were successful in removing some of it with a long-handled cutting tool; the small amount of line remaining likely did not play a significant role in the calf’s disappearance. Unfortunately, the 2010 calf of FB79 (C797) was entangled much more severely in fishing line from at least five different entanglements. In spite of our disentanglement efforts, he did not survive.

The majority of our elderly animals have survived another year, with the exception of FB36 who died this fall at age 39.

Number of identifiable dolphins using Sarasota Bay
Number of identifiable dolphins using Sarasota Bay on a regular basis; 96% of dolphins seen in the bay are identifiable.

The oldest male observed this year was FB28 (age 46), but he is a youngster compared to female Nicklo, who remains our oldest resident at 61 years young. She is often accompanied by Black Tip Double Dip (age 58), and the two are frequently seen just behind Mote Lab’s docks chasing fish over the seagrass meadow before whacking them out of the water with their tail flukes.

They are occasionally joined by another of the oldest females, Squiggy (age 55). In combination, the large number of successful calves and the small number of mortalities has the resident Sarasota Bay dolphin community at about 160 individuals, on a positive trajectory, moving in the direction of abundance levels reached at the turn of the century.

We have been able to continue our year-round monthly monitoring of the Sarasota bottlenose dolphin community thanks largely to support from the Batchelor Foundation, the Disney Worldwide Conservation Fund, and private donations, as well as the continued dedication of our core volunteers and undergraduate interns.

Thanks to these efforts, this community remains one of the most thoroughly studied free-ranging dolphin populations in the world.

 

 

Deepwater Horizon Oil Spill: 2010-2011 Efforts to respond to threats to dolphins along the central west coast of Florida

Much concern surrounded the potential catastrophic impacts of the April 2010 Deepwater Horizon (DWH) oil spill on wildlife and habitats in the Gulf of Mexico.

Long-term Gulf resident “Bracket” and her most recent calf,
Long-term Gulf resident “Bracket” and her most recent calf, seen here in September 2010.

The most common cetaceans in inshore waters of the Gulf, bottlenose dolphins, reside in coastal waters and bays, sounds, and estuaries where exposure to oil from the DWH incident was likely to occur. Prior to the DWH spill, little was known about the effects of oil spills on dolphins. There are a number of potential routes by which dolphins may be exposed to oil or associated chemicals such as inhalation, ingestion, and direct contact. Without the ability to predict the extent to which the spill would impact the Gulf coast and associated marine mammals, there was a strong need to collect baseline and control data for dolphin populations that might have been impacted directly or that might serve as comparative populations for those that are directly impacted, so that we can better understand the impacts of oil spills on cetaceans.

With the help of the Morris Animal Foundation’s Betty White Wildlife Rapid Response Fund, we initiated a project to address potential impacts on Gulf of Mexico bottlenose dolphins, specifically targeting stocks off the central west coast of Florida. The targeted stocks included the resident Sarasota Bay dolphin community, for which long-term health and population data were available, and the dolphins inhabiting the coastal waters of the Gulf of Mexico immediately offshore of Sarasota Bay, which likely would be exposed to oil before Sarasota Bay. Baseline data were collected on contaminant exposure, reproductive status, abundance, and distribution patterns of dolphins in these regions. We could not assign a probability to the oil spill spreading to Sarasota. If oil had arrived, then we would have collected exposure-response information that may be applicable for estimation of risks to other Gulf of Mexico cetacean populations. However, since the oil did not reach Sarasota Bay and the surrounding Gulf waters, the results of this study are being used by NOAA as control data for interpretation of data arising from potentially impacted populations elsewhere in the Gulf, such as Barataria Bay, Louisiana.

Sighting map of Bracket
Sighting locations for “Bracket,” one of several potential long-term resident Gulf animals identified during this project.

Two well-tested approaches were used to obtain information on contaminant exposure, abundance, distribution, and residency patterns of bottlenose dolphins in Gulf of Mexico and Sarasota Bay waters: 1) biopsy sampling, and 2) photo-identification. A total of 61 tissue samples for contaminant exposure assessment were obtained from Gulf dolphins through remote biopsy sampling and from Sarasota Bay resident dolphins through capture-sample-release techniques. Currently, all biopsy samples are being analyzed by NOAA and other collaborators.

Photo-identification surveys were conducted in the Gulf study area during June/July 2010 and August/September 2010, and in Sarasota Bay surveys were ongoing, 10 days each month. Data obtained from the photo-identification surveys were utilized to estimate abundance, and identify distribution and residency patterns. There were no significant changes in overall dolphin abundance between survey periods, or as compared to normal, pre-spill patterns. However, dolphin distribution seemed to vary somewhat from one survey period to the next, with more individuals being sighted closer to the coast during June/July and a higher number of individuals offshore during August/September.

These results suggest that there may be differences in the distribution of Gulf dolphins through the year. Project findings also support the concept of long-term residency for Gulf dolphins in addition to those in Sarasota Bay. Over the past three decades, about 900 individuals have been identified at one time or another in the study area for this project. Of these, 218 were identified from our 2010 photographs, including four individuals first identified as far back as 1980, when the Sarasota Dolphin Research Program initiated systematic photographic identification surveys.

It will be important to monitor the dolphins in oil-impacted bays and elsewhere in the Gulf of Mexico over time (years) to see if health or reproductive problems develop as a result of their exposure to oil and dispersants, either from direct contact or from transfer through the ecosystem. To facilitate accurate interpretation of subsequent data from the oil-impacted areas, it is necessary to have control data from sites that were in the same general region but were spared from the original spill.

The samples collected from Sarasota Bay and associated Gulf of Mexico waters in 2010 are serving as important controls for such comparisons.

 

 

Single-pin satellite-linked transmitter design and testing

Electronic tags have proven to be valuable tools in assessing small cetacean movement patterns and habitat use.

While tag design and success rates have varied, problems associated with package size, attachment position on the dorsal fin, and number of attachment pins have, in some cases, shortened the predicted attachment duration or caused adverse impacts to the dorsal fins of the animals.

These results motivated the development of a new satellite-linked tag attachment design that would minimize negative impacts to the dorsal fin while maximizing transmitter longevity.

Computer flow simulation on tag on dorsal fin
Computer flow simulation of an electronic tag mounted on a bottlenose dolphin dorsal fin. The lines represent flow trajectories. Flow trajectory recirculation, such as just behind the attachment point, represents a region of higher drag.

In 2009, SDRP researchers along with collaborators from Bayside Hospital for Animals, NOAA, SirTrack Tracking Solutions, and the University of North Carolina Wilmington developed a new prototype satellite-linked transmitter that was lighter than its predecessors and was attached to the trailing edge of the dorsal fin via a modified plastic housing and two semi-rigid, plastic flanges with a single plastic pin.

The goals of this new transmitter design aimed to minimize detrimental effects on tagged individuals while maximizing satellite-linked transmission duration. In August 2009, three adult male bottlenose dolphins along the Georgia coast received this prototype, single-pin satellite-linked transmitter. All three tags transmitted over the 50 day estimate of battery life, and subsequent follow-up tracking suggested that the single-pin attachment design was less traumatic to the dorsal fin than previous tag designs. However, the reason for tag failure in all three cases varied (plastic pin sheering, migration, and battery failure).

Although this prototype tag was a step in the right direction, there have been few quantitative studies that have investigated the influence of hydrodynamic drag on tag retention. The aim of this current study was to simulate hydrodynamic drag on the single-pin satellite-linked tag utilized in Georgia and provide alternatives for drag reduction to be incorporated into future tag designs. Computational Fluid Dynamics studies were used to measure the drag on a variety of tag designs. Based upon the simulations, the regions of most significant drag were identified to be directly behind the attachment hex nuts, antenna, and aft end of the tag. To reduce drag behind the hex nuts, self-threading pan head screws replaced the hex nuts, which are flatter and minimize the drag in this region. The drag behind the antenna and trailing edge of the tag was reduced by fabricating drag-reducing fairings in these two regions of the tag. A larger plastic attachment pin (5/16 in diameter as opposed to 1/4 in) was also selected to reduce potential migration of the tag through the dorsal fin.

In August 2011, a NOAA sponsored health assessment of bottlenose dolphins was conducted in Barataria Bay, Louisiana, in response to the Deepwater Horizon oil spill that had occurred a year prior. In addition to determining the health effects caused by the oil spill, it was also necessary to identify ranging patterns of dolphins within the region. Thus, 25 dolphins were tagged with this new single-pin satellite-linked transmitter design to determine ranging patterns of individual dolphins within the Barataria Bay estuary. Follow-up monitoring of animal and tag condition was conducted by the Louisiana Department of Wildlife and Fisheries with training and assistance from SDRP staff, and more in-depth follow-up is being performed by NOAA and SDRP in November 2011. Preliminary results suggest that these new satellite-linked tags are transmitting, on average, for more than 70 days, which is a significant improvement over previous tag designs. In addition, five of these tags were deployed on Franciscana dolphins in Brazil in October, and Marta Cremer and her team are performing follow-up monitoring. Once follow-up monitoring has been completed, analysis of digital photographs detailing individual dolphins and their attached transmitters will provide insight into the reasons for tag failure and what modifications are necessary for improving this tag design.

 

Sampling dolphins in the wake of the Deepwater Horizon oil spill

The National Institute of Standards and Technology (NIST) continues to help the Sarasota Dolphin Research Program (SRDP) in the area of bottlenose dolphin health assessment. Since 2002, we have assisted the program by developing sample collection procedures, archiving samples in the NIST Marine Environmental Specimen Bank (Marine ESB), assisting in field collections, and analyzing dolphin samples for pollutants.

The Deepwater Horizon oil spill was a major factor influencing how we collaborated with the SRDP this year. NIST was asked by the National Oceanic and Atmospheric Administration (NOAA) to help in collecting data for use in assessing injury to bottlenose dolphins that resulted from the oil spill.

NIST helped NOAA’s assessment of the effects of the Deepwater Horizon oil spill on bottlenose dolphins by participating in dolphin health assessments at two locations, a reference location, Sarasota Bay, in collaboration with the SRDP, and in Barataria Bay, LA, a location that was oiled during the oil spill.

In addition, remote biopsy samples that were collected in St. Joseph Bay, FL, a region where oil was expected to reach but never did, have been stored at NIST for analysis.

We modified our existing sampling protocols for bottlenose dolphins that had focused mainly on the collection of samples for chlorine and bromine pollutants analysis to also include the collection of samples specifically for oil and oil metabolites.

NIST personnel were deployed to both dolphin health assessments to assist in sample collection and processing. Unlike previous years, NIST will have a minimal role in the analysis of samples.

This work will be done by a special NOAA laboratory dedicated to the analysis of oil spill-related samples. Results from sample analysis should shed light on the extent to which Barataria Bay bottlenose dolphins are exposed to oil relative to non-impacted Sarasota Bay and St. Joseph Bay dolphins.

Aside from oil spill-related samples, blood samples were collected from the two health assessments for archival in the Marine ESB in order to continue the time series of samples collected from the Sarasota bottlenose dolphin population. In addition, a pilot project was started to archive serum from dolphins for future use in understanding disease outbreaks or for use in health-marker related research.