Abstract
Elasmobranch anesthesia is largely restricted to a few choice products which have variable cost and availability between countries. At the Seas, there are many species of shark and ray which are handled for routine and medical examinations. Historically at our facility, tricaine methane sulfonate (MS-222 Argent Chemicals, Redmond, WA) has been used for elasmobranch anesthetic procedures due to its reliable and anticipated effects. In some circumstances, alternate immersion sedative methods have been investigated to reduce excitation during induction, reduce induction time, or improve recoveries.
Clove oil and its derivatives, isoeugenol (AQUI-S, Lower Hutt, New Zealand) and eugenol (AQUI-S 20E, Aquatactics, Kirkland, WA), have been reported to be effective anesthetics in several elasmobranch species, including Cephaloscyllium laticeps (Australian swellshark; 24.3 ppm)1, Heterodontus portusjacksoni (Port Jackson shark; 24.3 ppm)1, Mustelus californicus (grey smooth-hound; 45 ppm)2, Triakis semifasciata (leopard shark; 45 ppm)2, Hemiscyllium ocellatum (epaulette shark, 25–50 ppm)3, Rhinobatus typus (shovel nose ray; 25–50 ppm)3, and Rhinoptera bonasus (cownose ray; 50–100 ppm)3. AQUI-S 20E advantages over other drugs have included a wide margin of safety, fast recoveries, no water pH changes, water solubility, less adverse or avoidance response from fish and zero day withdrawal time.4 Our prior experience with AQUI-S in southern stingrays at Disney's Bahamian facility (Castaway Cay) showed many of these beneficial effects, but the product was only available internationally, with no import option into the United States. AQUI-S 20E is available in the United States, but requires enrollment in the Investigational New Animal Drug (INAD) exemption program. Detailed information on the INAD program is available at the following website: www.fws.gov/fisheries/aadap/inads-available/sedatives/aqui-s/index.html. INAD participation requires an annual application and renewal process to use the drug and step-wise documentation of all anesthetic events.
The species at the Seas that appear to have improved anesthesia over MS222 include: Dasyatis americana (southern stingray; 15–20 ppm), Mobula hypostoma (lesser devil ray, 15–20 ppm), Rhinoptera bonasus (cownose ray; 20–25 ppm), Sphyrna tiburo (bonnethead shark; 55 ppm), Sphyrna lewini (scalloped hammerhead, 65 ppm), Urogymnus asperrimus (porcupine ray; 20 ppm), and Rhinobatus typus (common shovelnose ray; 15 ppm). Beneficial effects have included reduced excitation during induction, reduced lactate and acidosis post induction, and smoother, more rapid anesthetic recoveries (species variability). Potential disadvantages include inappropriate dose levels for a species (note high variability in dose range), insufficient mixing in water to obtain desired effect, light sensitivity, and longer recoveries than with MS222 (species variability).
Overall, the introduction of this drug into the practice has significantly improved the quality of anesthesia in multiple elasmobranch species. Despite some paperwork, the time and financial investment has been worthwhile.
Acknowledgements
The authors would like to thank the animal husbandry and health teams at The Seas, Walt Disney World Resorts®. Thanks to Donald Neiffer (Smithsonian's National Zoo, Washington, DC) who initiated the use of this drug at our facility. Special thanks to Bonnie Johnson (INAD) for her patience with us and guiding us so well on the INAD process. Special thanks to Jane Capobianco, Geoff Pye, Lynn McDuffie and Juliana Walker for their help with the INAD application, maintenance and renewal process.
* Presenting author
Literature Cited
1. Frick LH, Reina RD, Walker TI. 2009. The physiological response of Port Jackson sharks and Australian swellsharks to sedation, gill-net capture, and repeated sampling in captivity. North American Journal of Fisheries Management. 29(1):127–139.
2. Silbernagel C, Yochem P. 2016. Effectiveness of the anesthetic aqui-s® 20e in marine finfish and elasmobranchs. Journal of Wildlife Diseases. 52(2s):S96–103.
3. Grusha DS. 2005. Investigation of the life history of the cownose ray, Rhinoptera bonasus (Mitchill 1815) (Doctoral dissertation, The College of William and Mary). www.vims.edu/library/Theses/Grusha05.pdf.
4. http://aquatactics.com/aqui-s-20e.