![]() ![]() Sand tiger sharks Carcharias taurus are one of fifteen extant species belonging to the Lamniformes order of sharks. Endocrine differences between successfully reproducing in situ females and aquarium females likely contribute to the limited reproductive success observed for this species in managed care and may be a reflection of diminished seasonal cues and environmental differences. ![]() ![]() ![]() For females in the ovulatory stage, in situ females had higher testosterone than aquarium females. Pre-ovulatory aquarium females had significantly higher concentrations of 17 β-estradiol, testosterone and progesterone than other reproductive stages. In contrast to in situ females, aquarium females often retained uterine eggs for 9-20 months after ovulation in the absence of a developing embryo(s). All aquarium females had a pattern of reproductive cycling that was consistent with alternating years of activity and rest with confirmed biennial ( n = 7) or triennial ( n = 3) reproductive cycles with spring seasonality. Reproductive regionalization was observed among in situ females with the majority (83%) of North Carolina females in an active state of reproduction and all Delaware females in a resting reproductive state. Nineteen aquarium females from five aquaria were examined longitudinally for two or more consecutive years. In situ sharks were sampled from Delaware Bay ( n = 29), North Carolina ( n = 39) and South Carolina ( n = 11) during April-November from 2015–2020. The reproductive cycle was divided into eight stages based on ovarian activity and uterine contents. Reproductive status of in situ and aquarium female sharks was assessed using ultrasonography and plasma hormone (17 β-estradiol, testosterone, and progesterone) monitoring. Additionally, comparison of reproductive observations from successfully reproducing in situ sharks and aquarium sharks may help elucidate reasons for lack of reproduction among aquarium sharks and aid the development of assisted reproductive techniques for managed populations. Animals in managed care, such as aquariums, provide the unique opportunity for longitudinal study in contrast to in situ sharks that are examined opportunistically, and at a single point in time. 9Central Park Aquatic Health, Buffalo, NY, United Statesįundamental characteristics of the reproductive biology of female sand tiger sharks Carcharias taurus are needed to understand the periodicity, seasonality and environmental factors essential for reproduction in this iconic species.8Ripley’s Aquarium of Canada, Toronto, ON, Canada.7Ripley’s Aquarium of the Smokies, Gatlinburg, TN, United States.6Wildlife Conservation Society, New York Aquarium, Brooklyn, NY, United States.5Georgia Aquarium, Atlanta, GA, United States.4North Carolina Aquariums, Raleigh, NC, United States.3Ripley’s Aquarium of Myrtle Beach, Myrtle Beach, SC, United States.2Delaware Biotechnology Institute, Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, United States.1South-East Zoo Alliance for Reproduction & Conservation, Yulee, FL, United States.Hyatt 6, Chris Buckner 7, Véronique Le, F. ![]()
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