Analysis of simulated Antarctic minke surveys using the "standard" method and the "direct duplicate" method

Branch, Trevor A

Analysis of simulated Antarctic minke surveys using the "standard" method and the "direct duplicate" method

Working Paper

2006

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

Four new scenarios (sc33–sc36) of simulated survey data are analysed using the “standard” distance sampling method and the direct duplicate method of Palka (1995). The new scenarios were “blind” in that true simulated densities and the factors included were not revealed. Estimated densities were 0.029, 0.021, 0.082, and 0.063 whales per km 2 for the four scenarios using the “standard” method, and 0.029, 0.020, 0.081, and 0.062 whales per km 2 for the direct duplicate method. Some negative bias in estimates is expected from the standard method due to whales on the trackline being missed by the surveys. If true, the direct duplicate method then failed to correct for this bias for these scenarios, as resulting estimates were very similar to those obtained from the “standard” method.

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