Physiological state predicts space use of sharks at a tourism provisioning site

Author(s)

Rangel, Bianca S. ; Moreira, Renata G. ; Rider, Mitchell J. ; Sulikowski, James A. ; Gallagher, Austin J. ; Heithaus, Michael R. ; Cooke, Steven J. ; Kaufman, Les ; Hammerschlag, Neil

• Document type: Journal article
• Source: ANIMAL BEHAVIOUR; v. 191, p. 15-pg., 2022-08-13.

Abstract

While a growing body of literature has shown that tourism provisioning can influence the behaviour of wildlife, how physiological state might be related to the nature and magnitude of these effects remains poorly understood. Physiological state, including reproductive and nutritional status, can have profound effects on an individual's behaviour and decision making. In the present study, we used multiple physiological markers related to reproductive (testosterone, 170-oestradiol and progesterone), metabolic (corticosteroids) and nutritional ecology (stable isotopes and fatty acids), integrated with ultrasonography and passive acoustic telemetry to explore the possible relationship between physiological condition and space use of tiger sharks, Galeocerdo cuvier, exposed to dive tourism provisioning. Large, nongravid female tiger sharks, with higher plasma steroid levels (i.e. testosterone, 170-oestradiol, relative corticosteroid), enriched delta N-15 and elevated nutritional status (in terms of fatty acids) spent proportionally more time at food provisioning sites compared to conspecifics. Testosterone levels also were positively correlated with the proportion of time spent at provisioning sites. Based on these results, we speculate that physiological condition plays a role in shaping the spatial behaviour of female tiger sharks within the context of food provisioning, whereby larger individuals, exhibiting higher testosterone levels and elevated nutritional status, show selective preferences for provisioning dive sites, where they outcompete conspecifics of relatively smaller size, lower testosterone levels and depressed nutritional state. While more studies are needed to explore whether sharks are making these decisions because of their physiological state or whether spending more time at provisioning sites results in altered physiological state, our findings highlight the importance of considering animal life stage, endocrine regulation, and nutritional condition when evaluating the biological impacts of provisioning tourism. (C) 2022 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 14/16320-7 - Impacts of climate/environmental change on the fauna: an integrative approach
• Grantee: Carlos Arturo Navas Iannini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 17/25273-0 - Ecophysiology and trophic relationships of elasmobranchs: biomarkers as tools for conservation
• Grantee: Bianca de Sousa Rangel
• Support Opportunities: Scholarships in Brazil - Doctorate