Nicks 'n' Notches Online
A monthly enewsletter from the
Sarasota Dolphin Research Program
December 2021
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Our Annual Report is Now Available |
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We’re pleased to share that our annual report, Nicks’n’Notches is now available! This report provides a summary of our activities and accomplishments for the year, and as we continue into our second half-century, we want to acknowledge our appreciation for all who make it possible for this program to continue to conduct the world’s longest-running study of a wild dolphin population: our staff, students, volunteers, collaborators, donors, funding organizations, and the Chicago Zoological Society. Thank you for helping to make our first 50 years so successful, and helping us to continue our work to benefit dolphins!
An interesting note about the cover of this year’s report: Dolphins develop individually distinctive signature whistles that they use to make contact with one another and maintain group cohesion. The cover image, provided by our colleague Dr. Laela Sayigh, is a visual representation showcasing the signature whistles of each of the 269 Sarasota dolphins that have been recorded since the mid-1980s!
If you’d like to receive one or more hard copies of this edition of Nicks’n’Notches, please email us at info@SarasotaDolphin.org. Please put "annual report" in the subject line and be sure to include your current mailing address.
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Notes from the Field and Lab |
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We’re closing out 2021 with some positive news to report: On Dec. 2, we documented the 22nd calf of the year, breaking the record of 21 calves documented in 2017! The newest calf’s mother is 44-year-old Squarenotch, who we have observed since 1980. This is her sixth documented calf.
I first met Squarenotch while I was working on my University of California, Santa Cruz, Ph.D. dissertation, “Structural Aspects of Dolphin Societies,” which I completed in 1986. For that research, I documented dolphins living in the inshore waters along the Southwest Florida coast from St. Petersburg south to Fort Myers Beach, and Squarenotch was one of the animals that more typically spent her time along the Gulf beaches near Sarasota.
It’s interesting to note that during my thesis work, I documented 466 dolphins. Today, our current photo-identification catalog for an expanded portion of Florida’s west coast contains more than 10 times this number, helping us to put the Sarasota dolphin community into perspective relative to other resident dolphin communities along Florida’s west coast. Such is the passage of time and the nature of long-term study!
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Squarenotch and her sixth calf on Dec. 2. |
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While it’s exciting to document new calves each year as one measure of the health of the Bay’s dolphin population and the health of the Bay itself, the long-term nature of our research allows us to drill deeper and consider the question of why we had a record number of births. It appears that the red tide that reached Sarasota Bay in 2018 may have played a role.
The red tide that entered Sarasota Bay in the summer of 2018 was unusually strong and lasted through the winter of 2018-2019, killing marine life and causing millions of dollars in losses to coastal economies. During and following the bloom, we:
- Caught fewer than half the average number of stingrays than expected during prey fish surveys conducted during the summers of 2019 and 2020. We've been conducting catch-and-release purse seine fish surveys in shallow seagrass meadows since 2004. These surveys provide information on the relative abundance of dolphin prey and other fish in Sarasota Bay.
- Used photographic identification surveys to determine that Sarasota Bay dolphins were bitten by sharks in record numbers in 2019 and 2020.
- Documented that 45 percent of the females that gave birth to calves in 2021 had lost dependent calves during or since the red tide. On average, 31 percent of Sarasota calves do not survive more than two years, so there were increased losses of calves during the red tide period.
Adding these facts together allows us to make some tentative inferences. We know that stingrays are a primary prey item for sharks. When a preferred prey is unavailable, they’ll look to alternatives. The loss of typical shark prey may have led to the increased interactions we documented between sharks and dolphins as alternative prey. That allows us to infer that increased shark predation accounts for at least some of the losses of dependent calves during that period. When we document decreased ray catches, we tend to see increased disappearances of young dolphin calves.
Since Sarasota dolphins typically rear their young for about four years, the loss of dependent calves before that age during and following the red tide meant that more females were available to reproduce, likely contributing to the increase in the number of births this year.
The record number of births is a wonderful story in itself, but thanks to our long-term data, we’re able to develop hypotheses about some of the factors that may have led to this result, which should lead to a better understanding of what can happen to an animal population when an environmental anomaly occurs.
I especially want to thank the Charles & Margery Barancik Foundation, which has provided the primary ongoing support for our photographic identification and prey fish surveys. This funding is key to continuing our long-term fieldwork and for helping us better understand the hidden lives of dolphins!
Here’s wishing you fair winds and following seas as we sail through the end of 2021 and welcome in a new year!
Randy Wells
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Instead of a Fin of the Month, here’s a compilation of the 22 calves born this year! For more information on each calf and mom, please visit this story on our website, where you can "flip" the pictures in the photo gallery and learn more about the dolphins.
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Read more: other stories of note from the SDRP |
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A new SDRP study published in the journal Frontiers in Marine Science is helping us to understand how the dolphins’ prey community changes during red tide blooms and what that could mean for resident dolphin populations.
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When Dolphins and Freshwater Mix:
Prolonged exposure to freshwater is linked to adverse health conditions, immune deficiencies, and even dolphin deaths, but there’s still a lot we don’t understand. SDRP Post-doctoral Scientist Dr. Christina Toms was conducting photo identification surveys in Pensacola Bay when historic rainfall sent a surge a freshwater into the Bay. What did she find? Read more about her study published in the journal PLOS One.
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Exploring Microbiomes:
The science of microbiomes has received increasing attention over the past few decades, especially in the context of understanding animal health.
Working with colleagues at a variety of institutions, the SDRP has co-authored studies looking at the microbiomes of Sarasota Bay bottlenose dolphins, and sharks, skates and rays.
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Celebrating More than 50 Years of Research, Conservation and Education
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Support Dolphin Research Today |
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Each year, it takes approximately $1 million to fund the Sarasota Dolphin Research Program. Each grant and each gift helps to ensure that we can continue to learn about and help some of the world’s most fascinating creatures.
You can help ensure the future of this important and unparalleled wild dolphin research by making a gift today.
Gift options
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Donate to the Dolphin Biology Research Institute. This Sarasota-based nonprofit organization was established in 1982 to provide critical logistical and other operational support to the Sarasota Dolphin Research Program.
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For more information on how you can help support wild dolphin research, please contact Cindy Zeigler, CZS Chief Advancement Officer, at cindy.zeigler@czs.org or 708.688.8263.
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Dolphin Biology Research Institute — DBA Sarasota Dolphin Research Program — is dedicated to research and conservation of dolphins and their habitat. Community Foundation of Sarasota County Giving Partner Profile available here.
DBRI IS A 501(C)3 ORGANIZATION — FEDERAL TAX ID #59-2288387. A COPY OF THE OFFICIAL REGISTRATION (#CH1172) AND FINANCIAL INFORMATION MAY BE OBTAINED FROM THE DIVISION OF CONSUMER SERVICES BY CALLING TOLL-FREE 1-800-435-7352 WITHIN THE STATE OR AT WWW.FDACS.GOV/CONSUMER-RESOURCES/CHARITIES. REGISTRATION DOES NOT IMPLY ENDORSEMENT, APPROVAL, OR RECOMMENDATION BY THE STATE.
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