Abstract

Scalloped hammerheads (Sphyrna lewini) are rare in aquaria and, when held, are often not handled due to their flighty nature, sensitivity to restraint-induced acidosis, and propensity for skin injury. At the Seas, methods were developed to handle their four animals in order to facilitate routine and medical care. A multimodal approach was employed, utilizing behavioral training, strategic restraint and housing methods, specialized equipment, and development of suitable anesthetic protocols. Holding areas were outfitted with smooth walls, and exclusionary devices were put in place to prevent the sharks from rubbing against them, a common problem of most sphyrnids. In order to mitigate restraint time and physical exertion, animals were trained to swim over a net for initial capture. Smooth-sided tubs, some with modified lining, were utilized for all tanks during procedures. Handlers wore smooth, long gloves with limited skin/body contact and minimal, but evenly applied pressure when holding the animal. Multiple anesthetic approaches were used. In the most refined technique, sharks were immersed in eugenol (65–75 ppm, Aqui-S 20e, Aquatactics, WA) for induction, and monitored until recumbent. Assisted ventilation was applied as soon as possible and maintained throughout. Once anesthetized, an animal was placed in a smooth stretcher and transferred to a low-dose tricaine methanesulfonate (60 ppm, buffered MS222, Argent Chemicals) tank for maintenance. Blood gasses were obtained and monitored at first opportunity and prior to recovery. The ideal restraint scenario included a quick induction with minimal reactivity, strong respirations, good cardiac contractility, negligible iatrogenic skin injury, mitigation of acidosis, and rapid return to function from anesthesia (self-swimming within minutes, return to eating shortly after procedure). In two cases, animals were handled twice per week for several weeks to manage rostral and ocular abrasions sustained while in holding. While this species can be challenging, with modified techniques, they can be safely and repeatedly restrained.

Acknowledgements

The authors would like to thank the animal care and health teams at the The Seas, Walt Disney World Resorts® for their skill in caring for these animals and being innovative in their restraint techniques. Special thanks to Mike Hyatt (Adventure Aquarium, NJ), Michael Murray (Monterey Bay Aquarium, CA), and Shayne Boylan (South Carolina Aquarium, SC) for always sharing their knowledge and expertise, in particular on this species.

* Presenting author