Browsing by Subject "African Penguin"

Now showing 1 - 3 of 3
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    African penguins Spheniscus demersus recolonise a formerly abandoned nesting locality in Namibia
    (2003) Roux, J-P; Kemper, J; Bartlett, P A; Dyer, B M; Dundee, B L
    African Penguins Spheniscus demersus disappeared from Neglectus Islet probably between 1885 and 1952. Visiting birds were only noted rarely before the mid 1990s, but since 1995 penguin numbers on the islet have increased and breeding was first confirmed in 2001. Neglectus Islet is the only formerly abandoned nesting locality to be recolonised by African Penguins in Namibia. Although the population is still very small (estimated at around 11 breeding pairs), the re-establishment of this breeding locality is important for the conservation of the African Penguin, which is considered to be Critically Endangered in Namibia.
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    Aspects of modelling Robben Island African Penguin Spheniscus demersus populations
    (2006) Plagányi, Éva E; Butterworth, Doug S
    Crawford et al. (2006) present relationships between the breeding success of Robben Island African penguins Spheniscus demersus and the abundances of both anchovy Engraulis encrasicolus and sardine Sardinops sagax. Based on their analysis, they suggest that the management of the purse-seine fishery should ensure adequate escapement of fish to maintain the combined biomass of anchovy and sardine above two million tons. Given that this potentially has important repercussions for the management of the pelagic fishery, their analyses have highlighted the importance of further and more detailed investigations into this issue. This paper provides a brief summary of some further considerations in this regard.
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    Updated results from a Spatial Age-Structured Model of African Penguin populations for use in linking to the pelagic OMP testing process
    (University of Cape Town, 2008) Robinson, William M L; Plagányi, Éva E
    Updated results of an earlier penguin model are presented. The model focuses on four colonies 1) Robben Island; 2) Dassen Island; 3) Boulders and 4) Dyer island, although projections will narrow the focus further to the first two of these. Some progress has been made in terms of fitting the model adequately to historic data. However, there are still problems with the fits such that the current model is not yet at the stage where it can be linked to the pelagic OMP (Operational Management Procedure) testing process to take account of the relationship between the breeding success and also natural mortality of African penguins and the abundance of both anchovy Engraulis encrasicolus and/or sardine Sardinops sagax. Despite extensive investigations, in many cases no overly strong functional relationships between penguin breeding success and pelagic abundance have been found. As a result, functional relationships are being investigated between the natural mortality of African penguins and pelagic abundance, with results suggesting that a relationship exists at Robben Island, but not at Dassen Island. Dassen and Robben Islands are split and modelled separately for these and other reasons.