Browsing by Author "Edwards, Charlie"

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    Allee effects and their potential relevance to exploited abalone populations
    (2007) De Decker, Michelle; Edwards, Charlie; Butterworth, Doug S
    The Allee effect refers to the per capita growth rate of a population r (i.e. the increase in population size per individual present) and how this property changes at low population sizes. As a population is reduced below it’s carrying capacity, it is generally assumed that r will increase. However at very low levels, further reductions in population size may lead to decreases in r, so that recovery of the population is impeded. This is the Allee effect. In extreme cases r may even become negative, leading to population collapse.
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    Summary of the GLM used to standardize abalone catch-per-unit-effort data for Zones A-D over the period 1980-2006
    (2007) Plagányi, Éva E; Edwards, Charlie
    The General Linear Model (GLM) approach used last year is here updated for use in standardising the commercial abalone CPUE time series (1980 – 2006) of abalone for the influence of other factors on the CPUE apart from resource abundance. The raw data were supplied by A. Mackenzie (MCM). The explanatory variables included in the GLM are as in previous years. The same is true for the interaction terms in the model. The purpose of refitting a GLM to the abalone data is to update the results of Plaganyi (2006) using the data available for the 2006 Model year (October 2005 – September 2006). The method described by Plaganyi (2006) has been replicated as far as possible.