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Responses to matters raised in documents MARAM/IWS/DEC14/Peng/A1 and Peng/A2

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posted on 22.07.2022, 09:11 authored by Doug ButterworthDoug Butterworth, William Robinson

Responses are provided to a large number of the comments and assertions made in documents MARAM/IWS/DEC14/Peng/A1 and Peng/A2, primarily insofar as they relate to earlier analyses by the MARAM Group. Amongst the more important of these responses are the provision of a number of reasons why standard sample size weighting may not be appropriate for the types of analyses reported in MARAM/IWS/DEC14/Peng/B4 of the data from the island closure feasibility study (though this is being examined further for subsequent report to the Panel), and why the use of simpler models using fewer data may be preferable for such analyses. 

Peng/A2 is considered to fail to provide a clear explanation of the rationale for its assertion that weak catch vs biomass correlations at the local level can lead to spurious indications from GLM analyses that the impact of fishing on penguins is positive; at the very least, this assertion needs to be confirmed by an appropriate simulation study before it might merit further consideration. 

The advocacy in Peng/A2 for closure to replace catch as a covariate in the feasibility study analyses is questioned, particularly in the light of the associated implication that annual catches of nearly (and in one case exactly) zero have the same potential expected impact on penguins as the much larger catches that have been made in some other years.

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Department/Unit

Department of Mathematics and Applied Mathematics, University of Cape Town