# Minimizing Stress in White Sharks: Non-Invasive Epidermal Biopsies for Isotopic and Vitellogenin Analyses

## TL;DR

This study shows that non-invasive skin biopsies can help monitor stress and pollution in white sharks without harming them.

## Contribution

The use of minimally invasive epidermal biopsies for isotopic and vitellogenin analyses in white sharks is demonstrated for the first time.

## Key findings

- Vitellogenin, a marker of estrogenic exposure, was found in male and immature female white sharks.
- Dermal tissue alone is sufficient for stable isotope analyses, avoiding deeper muscle sampling.
- Estrogenic pollutants are widespread in South Africa’s white shark population.

## Abstract

White sharks (Carcharodon carcharias), apex predators crucial to marine ecosystems, face numerous anthropogenic threats, including endocrine-disrupting chemicals, primarily acquired through their diet. To advance their conservation, we investigated the use of minimally invasive epidermal biopsies for isotopic and vitellogenin analyses. These techniques provide critical insights into shark feeding habits and pollutant exposure without significantly stressing the animals. Our findings suggest widespread estrogenic exposure in South Africa’s white shark population, raising concerns about reproductive and ecological impacts.

The great white shark (Carcharodon carcharias), a keystone predator vital to marine ecosystem stability, is increasingly exposed to anthropogenic threats, including endocrine-disrupting chemicals (EDCs). This study highlights the use of non-invasive epidermal biopsies to assess physiological and ecological parameters in 28 live specimens sampled from the Dyer Island Nature Reserve, South Africa. Epidermal tissue was analyzed for vitellogenin (Vtg), a biomarker of estrogenic exposure, while dermal tissue was used for stable isotope analyses of carbon and nitrogen, essential for understanding the feeding habitat of white sharks. Vitellogenin, typically restricted to sexually mature females, was unexpectedly detected in males and immature females, indicating significant exposure to estrogenic pollutants. This finding raises concerns about the potential reproductive and population-level impacts on this vulnerable species. Stable isotope analyses confirmed that dermal tissue alone is sufficient for trophic studies, eliminating the need for deeper muscle sampling. By demonstrating that epidermal and dermal tissues provide critical data for both biomarkers and isotopic studies, this research supports the adoption of minimally invasive techniques. Shallower biopsies reduce stress on the animals, making this method a valuable tool for conservation research and management of C. carcharias.