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ESR 33:143-158 (2017)  -  DOI: https://doi.org/10.3354/esr00775

Low reproductive success rates of common bottlenose dolphins Tursiops truncatus in the northern Gulf of Mexico following the Deepwater Horizon disaster (2010-2015)

Nicholas M. Kellar1,*, Todd R. Speakman2, Cynthia R. Smith3, Suzanne M. Lane2, Brian C. Balmer2,4, Marisa L. Trego1, Krista N. Catelani1, Michelle N. Robbins1, Camryn D. Allen1, Randall S. Wells4, Eric S. Zolman2, Teresa K. Rowles5, Lori H. Schwacke2

1Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA
2Hollings Marine Laboratory, National Centers for Coastal Ocean Science, National Oceanic and Atmospheric Administration, 331 Fort Johnson Road, Charleston, SC 29412, USA
3National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, CA 92106, USA
4Chicago Zoological Society, c/o Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA
5Office of Protected Resources, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East West Highway, Silver Spring, MD 20910, USA
*Corresponding author:

ABSTRACT: Following the Deepwater Horizon (DWH) oil spill, reproductive success rates in 2 northern Gulf of Mexico (GoM) bottlenose dolphin stocks exposed to oil were evaluated for 4 yr during and after the spill (2010 to 2015) in efforts to assess population-level reproductive health. Pregnancy was determined from either (1) ultrasound examinations of the reproductive tract during capture-release health assessments, or (2) endocrine evaluations of blubber tissue collected from dart biopsies of free-ranging dolphins. Follow-up photo-identification was then used to track the status of pregnant females and any associated neonatal calves for a minimum of 1 yr after the initial pregnancy detection (IPD). For all pregnant females observed following IPD, individuals seen with a calf (reproductive success) and without one (reproductive failure) were recorded. The resulting estimated reproductive success rates for both GoM stocks (19.4%; 7/36) were less than a third of those previously reported in other areas not impacted by the spill (i.e. Sarasota Bay, FL; Indian River Lagoon, FL; and Charleston Harbor, SC) using similar techniques (64.7%; 22/34). We also evaluated the relationships between reproductive success and 13 potential covariates, including stock, ordinal date, progesterone, cortisol, thyroid hormone concentrations, leukocyte count, lung health score, and total body length. Among these, the results only provide strong evidence (Bayes factor >20) of a relationship between reproductive failure and the total leukocyte count covariate. The high reproductive failure rates measured in both GoM stocks following the DWH oil spill are consistent with mammalian literature that shows a link between petroleum exposure and reproductive abnormalities and failures.


KEY WORDS: Oil spill · Petroleum · Pregnancy · Reproductive failure · Cetacean · Blubber progesterone · Ultrasound


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Cite this article as: Kellar NM, Speakman TR, Smith CR, Lane SM and others (2017) Low reproductive success rates of common bottlenose dolphins Tursiops truncatus in the northern Gulf of Mexico following the Deepwater Horizon disaster (2010-2015). Endang Species Res 33:143-158. https://doi.org/10.3354/esr00775

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Published in ESR Vol. 33. Online publication date: January 31, 2017
Print ISSN: 1863-5407; Online ISSN: 1613-4796
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