About This Project

Sharks are sensitive to capture and handling. The stress response during commercial bycatch, recreational catch-and-release, and research fisheries captures may be exacerbated in certain environmental conditions. We're evaluating bull and bonnethead sharks' stress responses from measurements of their blood, when caught in waters of differing parameters (temperature, salinity, and dissolved oxygen). Findings may support capture and handling recommendations to minimize acute and delayed mortality.

Ask the Scientists

What is the context of this research?

It is well established that water quality parameters (e.g., temperature, salinity, and dissolved oxygen or DO) affect the metabolism and osmoregulation of bony fishes; however, their effects on the shark stress response are not well studied. Elevated temperature appears to increase the stress response, leading to a more extensive decrease in blood and tissue pH (also known as acidosis) and increased mortality, in both fishes and sharks. Studies have shown varying effects on acid-base, blood gas and metabolic disturbances in fishes. To our knowledge, there are no data on acid-base or blood gas changes in sharks exposed to different salinities or DO that may exacerbate a concurrent response to an acute stressor. For more details on shark stress physiology, check out my post in Lab Notes.

What is the significance of this project?

If bull and bonnethead sharks are found to have increased stress responses in certain water quality conditions that could lead to increased mortality, then findings will offer evidence to support capture and handling recommendations to commercial, recreational, and research fisheries. This can encourage diligence in shark capture and handling in warm waters by decreasing soak times, continually monitoring gear, releasing hooked sharks promptly after capture and detection, and executing veterinary examination, diagnostics, and treatments promptly; all with the goal of minimizing acute and delayed mortality.

What are the goals of the project?

The goal of this study is to assess the effects of environmental variation on the stress response to capture and handling in bonnethead and bull sharks in order to guide the formulation of capture and handling recommendations to minimize acute and delayed mortality of captured sharks in commercial and recreational fisheries, and in fisheries research. The objectives are to conduct analyses to: 1) determine appropriate temperature corrections, 2) determine the nature of data distributions to guide subsequent analytical methods, 3) determine the nature of relationships among water quality variables, 4) model the effects of water quality parameters on the blood gas response of sharks, and 5) publish results in the Journal of Coastal Research.