Short-term response of research activities on white shark behaviour

Context: Researchers studying animals need to ensure that sampling procedures and the methods they use are as harmless and non-disruptive as possible, particularly when their focal species are threatened or protected. White sharks (Carcharodon carcharias) are Vulnerable under the IUCN Red List, protected globally, and are frequently studied by marine ecologists. Aims: To assess white shark responses to research activities (i.e. tagging and biopsy procedures, and electric deterrent trials) conducted at the Neptune Islands Group Marine Park (South Australia, Australia). Methods: Trends in shark residency following research activities were assessed by comparing shark abundance (number of sharks detected by acoustic receivers and sighted by cage-diving operators) before, during, and after scientific expeditions, and to natural fluctuations in the absence of research activities using 8 years (2013-2021) of acoustic tracking and daily sighting reports from a wildlife tourism industry. Key results: Number of white sharks and residency decreased after sampling. However, changes observed following research activities were similar to natural fluctuations, suggesting that these changes reflected natural variations rather than being due to sharks responding negatively to the research activities. Conclusions: Our study showed that external tagging, biopsies, or deterrent trials do not affect short- and long-term residency or abundance of white sharks, probably owing to the research activities being minimally intrusive and to sharks having efficient immune systems and remarkable ability to heal from injuries.