Penguins’ perilous conservation status calls for complementary approach based on sound ecological principles: reply to Butterworth et al. (2015)

Weller, Florian; Sherley, Richard B.; Shannon, Lynne J.; Jarre, Astrid; Stewart, Theodor J.; Scott, Leanne; Altwegg, Res; Cecchini, Lee-Anne; Crawford, Robert J. M.; Geldenhuys, Deon; Ludynia, Katrin; Waller, Lauren J.

doi:10.1016/j.ecolmodel.2016.06.002

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…However, these were restricted to 2 years of closure [ 9 ] and a single colony [ 8 ], and the magnitude and nature of these effects made it difficult to ascertain whether these small-scale, short-term fishing closures would generate meaningful long-term demographic benefits [ 9 , 18 ]. Given the importance of the underlying environmental conditions in driving penguin demography [ 4 , 18 ], it is unsurprising therefore that the conservation value of these closures relative to the socio-economic costs of restricting fishing—and so whether they should remain in place—is hotly debated [ 19 – 21 ].…”

Section: Introductionmentioning

confidence: 99%

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

Sherley

Barham

et al. 2018

Proc. R. Soc. B.

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Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time–area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator—we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers.

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Section: Introductionmentioning

confidence: 99%

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

Sherley

Barham

et al. 2018

Proc. R. Soc. B.

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“…Work along these lines has focused predominately on a 12-year experiment, started in 2008, to investigate the effects of fishing closures around penguin breeding colonies. The experiment has shown some benefits to breeding penguins through a decrease in foraging effort and an increase in chick growth and condition when fishing was prohibited (Pichegru et al, 2012;Sherley et al, 2015Sherley et al, , 2018 Weller et al, 2016). The recent stability of breeding numbers at Simonstown (small pelagic fishing in False Bay has been prohibited since 1982, Penney, 1991) and Stony Point (which is surrounded by a small marine protected area) during a period when the populations at all the other South African colonies have declined also provides circumstantial evidence in support of protecting the key foraging areas used by breeders.…”

Section: Discussionmentioning

confidence: 99%

The conservation status and population decline of the African penguin deconstructed in space and time

Sherley

Crawford²,

Blocq³

et al. 2020

Ecology and Evolution

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“…The influence of resource competition by the purse-seine fishery on the demographic parameters of breeding African penguins has been investigated in an experiment that included two paired breeding island groups with alternating closures every 3 years 24 , 52 . The results have shown positive impacts of no-take zones on breeding and foraging parameters 24 , 52 , 53 , although these results have been contested 54 , 55 . However, the design of these no-take zones (i.e.…”

Section: Introductionmentioning

confidence: 98%

Important marine areas for endangered African penguins before and after the crucial stage of moulting

Carpenter-Kling

Blocq²,

Hagen³

et al. 2022

Sci Rep

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The population of the Endangered African penguin Spheniscus demersus has decreased by > 65% in the last 20 years. A major driver of this decrease has been the reduced availability of their principal prey, sardine Sardinops sagax and anchovy Engraulis encrasicolus. To date, conservation efforts to improve prey availability have focused on spatial management strategies to reduce resource competition with purse-seine fisheries during the breeding season. However, penguins also undergo an annual catastrophic moult when they are unable to feed for several weeks. Before moulting they must accumulate sufficient energy stores to survive this critical life-history stage. Using GPS tracking data collected between 2012 and 2019, we identify important foraging areas for pre- and post-moult African penguins at three of their major colonies in South Africa: Dassen Island and Stony Point (Western Cape) and Bird Island (Eastern Cape). The foraging ranges of pre- and post-moult adult African penguins (c. 600 km from colony) was far greater than that previously observed for breeding penguins (c. 50 km from colony) and varied considerably between sites, years and pre- and post-moult stages. Despite their more extensive range during the non-breeding season, waters within 20 and 50 km of their breeding colonies were used intensively and represent important foraging areas to pre- and post-moult penguins. Furthermore, penguins in the Western Cape travelled significantly further than those in the Eastern Cape which is likely a reflection of the poor prey availability along the west coast of South Africa. Our findings identify important marine areas for pre- and post-moult African penguins and support for the expansion of fisheries-related spatio-temporal management strategies to help conserve African penguins outside the breeding season.

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Penguins’ perilous conservation status calls for complementary approach based on sound ecological principles: reply to Butterworth et al. (2015)

Cited by 5 publications

References 12 publications

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

The conservation status and population decline of the African penguin deconstructed in space and time

Important marine areas for endangered African penguins before and after the crucial stage of moulting

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