Stress Test: what’s the impact of US recreational fishery capture on prohibited sharks?
White, dusky, and sand tiger sharks are protected in U.S. waters but frequently caught and released by recreational anglers. Their survival after release is uncertain. In the New York Bight, intensive recreational fishing activity overlaps with seasonal aggregations of juvenile sand tiger sharks and habitat for dusky sharks. Studies in commercial fisheries have shown that dusky and sand tiger sharks often don’t fare well after release. Lindsay is measuring how capture stress affects survival, focusing on the rod-and-reel recreational fisheries whose impacts we know little about. She will generate guidelines to reduce handling stress, improve survivorship, and strengthen recovery efforts for three of the Atlantic’s most threatened shark species.
Lindsay L. Graff
I was born and raised in the landlocked state of Vermont, but I never believed proximity to the ocean determines whether someone falls in love with the sea. As a child, I explored every pond, lake, stream, river, tidal pool and coastline I could reach, endlessly fascinated by the diversity of marine life I encountered. During my undergraduate studies in zoology at Connecticut College, I studied abroad in the Turks and Caicos Islands, where I was mentored by a female shark biologist. That experience was transformative – at 19, I realised that studying sharks could be more than...
Evaluating capture stress for three prohibited shark species incidentally caught in U.S. recreational fisheries
To evaluate how capture stress affects white, dusky and sand tiger sharks in the New York Bight by analysing blood-based stress biomarkers and linking them with post-release survival and behaviour.
White, dusky and sand tiger sharks are protected in US waters but are still frequently caught and released by recreational anglers. The survival of these sharks after release is uncertain, creating a gap in conservation planning. By measuring how capture stress affects survival, this project will generate science-based guidelines to reduce handling stress, improve survival and strengthen recovery efforts for three of the Atlantic’s most threatened shark species.
Sharks are apex predators that maintain balance in marine ecosystems, yet many populations have declined due to overfishing and incidental capture. White Carcharodon carcharias, dusky Carcharhinus obscurus and sand tiger Carcharias taurus sharks are particularly vulnerable because they grow slowly, mature late and reproduce at very low rates. Despite their legal protection, these species are caught incidentally in both commercial and recreational fisheries, raising concerns that post-release mortality may reduce their ability to recover. Although commercial post-release mortality has been studied to some extent, far less is known about recreational rod-and-reel impacts.
The New York Bight is a high-use habitat where intensive fishing activity coincides with critical shark life stages. Nearshore waters serve as nursery grounds for young-of-the-year white sharks, support seasonal aggregations of juvenile sand tiger sharks and provide habitat for dusky sharks. The spatial overlap between vulnerable shark populations and recreational fisheries heightens the risk of capture during routine fishing activities, making the region a priority for evaluating post-release mortality and bycatch impacts.
Studies in commercial fisheries have shown high post-release mortality for dusky and sand tiger sharks, which is often linked to long fight times and poor physiological recovery. In contrast, recreational studies are rare. Research on sand tiger sharks has documented measurable physiological stress responses to rod-and-reel capture, but no comparable studies exist for white or dusky sharks. Without species-specific data from recreational fisheries, managers must rely on generalised assumptions that may underestimate true fishing mortality.
This project addresses that gap by collecting blood samples from sharks captured in the New York Bight and analysing biomarkers such as lactate, pH, glucose and electrolytes using field-portable devices and laboratory analyses. These physiological results will be paired with pop-up satellite archival tag (PSAT) data on survival and behaviour. Linking physiology with post-release outcomes will enable us to identify biomarkers that reliably predict mortality risk. These insights will be used to develop evidence-based handling guidelines for recreational anglers and managers, helping to reduce post-release mortality and ensure that existing protection measures translate into real conservation benefits for threatened shark populations.
- To quantify physiological stress responses in white, dusky and sand tiger sharks using blood-based biomarkers during recreational captures.
- To link blood chemistry with survival outcomes by combining new data with PSAT tagging and archived samples collected over the past decade.
- To develop evidence-based handling guidelines for recreational anglers and provide fisheries managers with species-specific recommendations to reduce stress and mortality.