Comment on “South Africa's experimental fisheries closures and recovery of the endangered African penguin” by Sydeman et al. (2021)

Abstract

Abstract An experiment involving alternating closures to pelagic fishing of the neighbourhoods around two pairs of nearby islands with breeding colonies of African penguins was initiated in South Africa in 2008, with the aim to determine the impact on penguin reproductive success. Based on their analyses of the experiment, Sydeman et al. (2021) assert that the closures reduce competition with fisheries on forage fish, and should be maintained. In contrast, based on analyses conducted in accordance with the recommendations of an international review panel, the South African Government's scientific committee responsible for overseeing and analysing the experiment conclude that when compared to the concerning decline over recent decades of some 5% pa in overall penguin abundance, the effect of maintaining such closures towards arresting that decline would at best be minimal. This Comment summarises the history of the experiment and associated analyses, and then points to a number of shortcomings of Sydeman et al. (2021), most seriously incorrect results from not adequately accounting for the effects of pseudoreplication. It is argued that the present priority is identifying the main factor(s) responsible for the penguin decline, since the experiment has shown that this is not fishing in the neighbourhood of penguin colonies.