Abstract
Sharks are sensitive to capture and handling stress caused by the physiological response of acidosis in the blood and tissues, which can result in death in some cases. This presents significant challenges in commercial fisheries, in catch-and-release recreational fishing, to scientists studying wild and captive sharks, and to veterinarians caring for sharks in public aquaria. For a more detailed review of acidosis in sharks, see Hyatt et al.5 In general, sharks become acidotic when pCO2 and lactate increase and pH decreases after exhaustive exercise due to metabolic and respiratory acidosis.1-7 This is a major reason that sharks experience a high rate of morbidity and mortality associated with capture and handling. To help assess post capture and release mortality, fisheries researchers may use a behavioral health assessment at release. The goal of this study was to evaluate blood gas analytes (pH, pCO2, HCO3 and lactate concentrations) among sharks of different given behavioral release condition scores (BRCS) to assess the accuracy of BRCS in estimating the physiological stress response. Blood gases of wild bull sharks (Carcharhinus leucas) and bonnethead sharks (Sphyrna tiburo) were measured with the i-STAT clinical analyzer utilizing the CG4+ cartridge immediately prior to release after tagging, handling and morphometric measurements were taken. Although blood gas analytes differed significantly among BRCS in both species; overall, they predicted BRCS with low accuracy (bull sharks, 57.1%; bonnethead sharks, 47.5%). Since the behavior of a shark does not always accurately reflect its physiological status, we alternatively recommend physiological assessment to evaluate stress imposed upon sharks caught as bycatch, in catch-and-release recreational fishing, and under veterinary care in public aquaria.
Acknowledgements
The authors wish to thank all the volunteers from the Rookery Bay National Estuarine Research Reserve, as well as S. Hanson, K. Heym, S. Coy, K. Aanerud, B. Orze, and A. Slagoski (The Florida Aquarium), who assisted in field work and data collection. The authors also would like to thank I. Berzins for her forethought, guidance and initiation of the research program that led to this presentation. This study was funded in part by The Shark Foundation. P. Anderson was supported in part by The Spurlino Foundation and an anonymous donor. Sharks were captured under the Florida Fish and Wildlife Conservation Commission Special Activities License 08SR-059.
* Presenting author
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