Bottom-up effects of a no-take zone on endangered penguin demographics

Abstract

This is the author's postprint version of the article. Data used for analyses in this manuscript are available in Dryad: http://dx.doi.org/10.5061/dryad.t446r. Supplementary materials are available under the Creative Commons License CC-BY version 4.0 at http://rsbl.royalsocietypublishing.org/content/roybiolett/suppl/2015/07/08/rsbl.2015.0237.DC1/rsbl20150237supp1.pdfThe definitive published version of the article is available via DOI: 10.1098/rsbl.2015.0237Marine no-take zones can have positive impacts for target species and are increasingly important management tools. However, whether they indirectly benefit higher order predators remains unclear. The endangered African penguin (Spheniscus demersus) depends on commercially exploited forage fish. We examined how chick survival responded to an experimental 3-year fishery closure around Robben Island, South Africa, controlling for variation in prey biomass and fishery catches. Chick survival increased by 18% when the closure was initiated, which alone led to a predicted 27% higher population compared with continued fishing. However, the modelled population continued to decline, probably because of high adult mortality linked to poor prey availability over larger spatial scales. Our results illustrate that small no-take zones can have bottom-up benefits for highly mobile marine predators, but are only one component of holistic, ecosystem-based management regimes.The Earthwatch InstituteThe Bristol Zoological SocietyThe Leiden Conservation FoundationThe National Research Foundation (South Africa