Simple biopsy modification to collect muscle samples from free-swimming sharks

Developing and enhancing non-lethal methods for sampling species of high conservation concern, including marine megafauna, has prompted the development of numerous biopsy methods to collect tissue for biochemical analyses. However, many of these analyses require adequately-sized muscle cores for reliable results. Here, we developed and trialed a novel modification to a biopsy probe traditionally limited to underwater use, which enables sampling of free-swimming sharks from above the surface. The modified probe used collected similar amounts of white shark, Carcharodon carcharias, muscle and sub-dermal tissue above water as the traditional underwater probe (muscle: 0.36 g vs. 0.44 g; sub-dermal tissue: 0.62 g vs. 0.44 g for surface and underwater respectively). Both methods obtained sufficient tissue for several analyses to be run on the same tissue core (e.g. stable isotopes, fatty acids, and genetics). This encourages the use of this biopsy probe, with studies assessing stock structure, trophic ecology, or physiology. The described modification adapts the probe to allow above-water deployment, providing more opportunities for effective, non-lethal sampling of free-swimming sharks.