Abstract

The understanding of stress and its impact on elasmobranch medicine and handling is an important topic of ongoing investigation. During stressful events fish elicit a wide range of life affecting physiologic responses, such as respiratory and metabolic acidosis,^1-8 which can greatly influence animal health in scenarios like medical examinations, fishing capture, and transportation.In particular, transporting pelagic sharks has in the past resulted in high rates of mortality and poor long term survival. In fact, mortality rates of some free range fish species after capture and release events reach as high as 94%.^5,7 By identifying species-specific blood indices associated with acid-base status during handling, we can evaluate restraint and capture techniques, anesthesia protocols, the viability of animals for transportation, and curtail the morbidity and mortality of elasmobranchs following capture situations.

The current study was designed to establish reference intervals of critical care blood analytes including blood gases, electrolytes, glucose, and lactate for a variety of elasmobranch species and to make comparisons between species of differing lifestyles and methods of respiration. When evaluating the clinical relevance of blood parameters in any species, it is important to recognize outlying factors which can influence the results, such as venipuncture site. Studies involving various fish species have identified variations in several hematologic and biochemical values along the circulatory system.^9,10 Thus, the current study, also compared i-STAT® blood analyte values between two commonly used elasmobranch venipuncture sites - the caudal tail and the dorsal fin. Pelagic, intermediate and benthic elasmobranchs at the John G Shedd Aquarium were immobilized for health screens. In addition, wild pelagic elasmobranch species were hook and line caught in the coastal waters of Florida several miles within the Keys during normal collecting trips for Dynasty Marine Associates. Wild caught animals were immediately brought boat-side, netted and manually restrained. Blood was obtained from the ventral tail artery and within 30 seconds from the dorsal sinus. Samples were immediately processed with the i-STAT (Heska, Fort Collins, CO 80525) portable clinical analyzer to run standard blood gas panels. Statistical comparisons were made for collection site, gender, and captivity status.

Acknowledgements

The authors thank John G. Shedd Aquarium, Dr. Ilze Berzins, Dr. Jeff Boehm and Chicago Zoological Society for their support, Dr. Dawn Zimmerman and Omaha's Henry Dourly Zoo, George Parsons, Stacy Schultz, and Dr. Michelle Davis for their technical support, Heska® veterinary products (Dr. Nancy Wisnewski) for their generous donations.

References

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