A novel, nonlethal liver biopsy procedure in an elasmobranch

Tissue sampling is essential for understanding the biology, health and conservation status of elasmobranchs (i.e., sharks and rays). Historically, these samples have been obtained through recreational and commercial fisheries or via fisheries-independent sampling, often involving lethal methods. However, with a significant number of elasmobranch species listed as conservation concerns under IUCN standards - approximately one-third of species are threatened with extinction - there is an urgent need for nonlethal tissue sampling techniques to optimise animal care and further conservation research. Recent advances have demonstrated nonlethal liver sampling in teleost fishes, but this has rarely been attempted in elasmobranchs. Yet, in elasmobranchs, the liver is one of the largest organs, performing critical functions such as buoyancy regulation, energy storage and metabolic processes. Here, we present a nonlethal liver biopsy procedure in an elasmobranch species, the epaulette shark (Hemiscyllium ocellatum). Individual sharks were wild-collected from coastal waters of Queensland, Australia and maintained in holding facilities at James Cook University and Heron Island Research station where all procedures took place. Following surgery, the sharks made a full recovery, accepted food within 24 hours, and were monitored for 2 weeks before being released back to their original collection sites after complete healing. This study aimed to showcase these methods as a foundation for improved veterinary care and conservation science, while also advocating for the broader adoption of nonlethal sampling techniques in both research and clinical practice to promote sustainability and ethical conservation efforts.