Collaborative Health Investigations on Wild North Atlantic Shark Populations
Shark populations around the world have declined drastically over the past four decades causing marine ecosystems to become unbalanced leading to disruptions in lower food webs.1-5 This has global consequences as it can affect human food supply, resources, and economics for an ever-growing human population.5 Sharks as apex predators are viewed as a sentinel species of the ocean, providing a model for studies of individual, population, and ecosystem health. Health assessments are crucial to determine baseline health parameters, understand stress physiology caused by handling, nutritional biomarkers to assess diet, and toxicological contaminants. This information can be used to elucidate the health status, understand trophic relationships and ecosystem threats, and guide conservation action in preferred habitats for these vulnerable species.6
The Wildlife Conservation Society’s (WCS) New York Aquarium has been tagging sharks in New York waters and within the north Atlantic since 2012 with acoustic and/or satellite tags to study their movements, site fidelity, habitat use, and migratory patterns. Collaborative, multi-institutional, multi-disciplined studies of various shark species in the north Atlantic is currently underway in partnership with various organizations such as NY Seascape, OCEARCH, and NOAA. Target species include sand tiger (Carcharhinus taurus), white (C. carcharias), shortfin mako (Isurus oxyrinchus), blue (Prionace glauca), sandbar (C. plumbeus), dusky (C. obscurus) and smooth dogfish (Mustelus canis) sharks. It is this work that led to the identification of a sand tiger nursery ground in Great South Bay, NY.7 Data collected will further be used to refine juvenile sand tiger Essential Fish Habitat maps. These projects are also part of WCS’s institution-wide 10-year global strategy, and collaborative for conserving sharks and rays called the Global Sharks and Rays Initiative.8 In addition, WCS is raising awareness about the conservation needs of these vulnerable species through engagement with AZA SAFE, which has identified sharks and rays as a top conservation target for their collective aquarium outreach and policy efforts.
The highlight of this research is the collaboration with OCEARCH, a non-profit marine research, conservation, and education organization that promotes shark conservation and sustainability. The objectives of this study are to perform health assessments on 20 young-of-the-year, 20 subadult, and 20 adult white sharks to: 1.) evaluate blood gas analysis for changes in pH, pCO2, and lactate as indicators of the secondary stress response; 2.) determine reference intervals for baseline hematology, biochemistry, protein, and acute phase protein parameters; 3.) determine baseline nutritional biomarkers; 4.) evaluate the burden of environmental contaminants; and 5.) determine post-release survivorship and long-term migration patterns through satellite telemetry. When evaluated collectively, the physical examination, ultrasonography, hematological and biochemical analyses, nutritional and environmental contaminant analyses, and post-release monitoring encompass a full-picture of the health of white sharks in the North Atlantic that will help establish a baseline from which to compare for future research and conservation efforts on this species. Understanding the health of this population may also inform future conservation strategies and policies with regard to human interaction such as fishing pressure, offshore energy development, habitat loss, pollution, climate change, and other human impacts.
The authors thank the crew of the M/V OCEARCH, support staff and production team. The authors also thank the numerous researchers over the years that have partaken on expeditions or have assisted in their respective laboratories. Funding for white shark health assessments aboard OCEARCH provided by the AZA Conservation Grants Fund and Disney Conservation Fund and Shark Foundation.
* Presenting author
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