Conservation implications of forage base requirements of a marine predator population at carrying capacity

Ruth E Dunn; Darcy Bradley; Michael R Heithaus; Jennifer E Caselle; Yannis P Papastamatiou

doi:10.1016/j.isci.2021.103646

Conservation implications of forage base requirements of a marine predator population at carrying capacity

iScience. 2021 Dec 16;25(1):103646. doi: 10.1016/j.isci.2021.103646. eCollection 2022 Jan 21.

Authors

Ruth E Dunn^{1

2}, Darcy Bradley³, Michael R Heithaus¹, Jennifer E Caselle³, Yannis P Papastamatiou¹

Affiliations

¹ Institute of Environment, Department of Biological Sciences, Florida International University, Miami, FL, USA.
² Lancaster Environment Centre, Lancaster University, Lancaster, UK.
³ Marine Science Institute, University of California, Santa Barbara, CA, USA.

Abstract

Prey depletion may contribute to marine predator declines, yet the forage base required to sustain an unfished population of predatory fish at carrying capacity is unknown. We integrated demographic and physiological data within a Bayesian bioenergetic model to estimate annual consumption of a gray reef shark (Carcharhinus amblyrhynchos) population at a remote Pacific atoll (Palmyra Atoll) that are at carrying capacity. Furthermore, we estimated the proportion of the atoll's reef fish biomass production consumed by the gray reef sharks, assuming sharks either partially foraged pelagically (mean 7%), or solely within the reef environment (mean 52%). We then predicted the gray reef shark population potential of other, less remote Pacific Ocean coral reef islands, illustrating that current populations are substantially smaller than could be supported by their forage base. Our research highlights the utility of modeling how far predator population sizes are from their expected carrying capacity in informing marine conservation.

Keywords: Biological sciences; Environmental science; Nature conservation; Physiology; Zoology.