A spatial model of African penguin Spheniscus demersus populations in the Western Cape

Plagányi, Éva E

A spatial model of African penguin Spheniscus demersus populations in the Western Cape

Working Paper

2007

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

A number of questions have recently been raised regarding the status and management of the African penguin Spheniscus demersus. The PWG penguin task team agreed that it would be useful to develop a dynamic model to assist in understanding the population dynamics as well as in an attempt to reconcile the various data sources. This document describes the development of such a model. Although still preliminary only, the model is of a form that can readily be linked to the pelagic OMP (Operational Management Procedure) to take account of the relationship between the breeding success of African penguins and the abundance of both anchovy Engraulis encrasicolus and/or sardine Sardinops sagax (e.g. Crawford et al. 2006). The aims of the current model are as follows: 1) To provide a dynamic representation of penguin dynamics; 2) To fit to available data to provide estimates of important demographic parameters such as survival rates, which can then be compared to other available estimates; 3) To attempt to reconcile some apparent contradictory trends in the different data series; 4) By gradually increasing the complexity of the model to represent different plausible hypotheses, the model should assist in identifying the most parsimonious hypothesis to explain the observed trends in the population; 5) To quantify and provide additional substantiation for the relationship between penguin breeding success and pelagic fish abundance; 6) To dynamically project the penguin population assuming various future scenarios to assist in providing advice regarding the management of the penguin population (and possibly pelagic fish populations as well).