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Issue Aquat. Living Resour. Volume 22, Number 2, April-June 2009 Fish Stock Assessments Using Surveys and Indicators Page(s) 193 - 200 DOI 10.1051/alr/2009020 Published online 17 June 2009

Aquat. Living Resour. 22 (2009) 193-200
DOI: 10.1051/alr/2009020

Using min/max autocorrelation factors of survey-based indicators to follow the evolution of fish stocks in time

Mathieu Woillez¹, Jacques Rivoirard² and Pierre Petitgas<sup>1

1</sup>  IFREMER, Département EMH, BP 21105, 44311 Nantes Cedex 03, France
²  Mines-ParisTech, Centre de Géosciences/Géostatistique, 35 rue St Honoré, 77300 Fontainebleau, France

Received 15 July 2008; Accepted 22 January 2009 ; Published online 17 June 2009.

Abstract - Fisheries research monitoring surveys provide an ensemble of measurements on fish stocks and their environment. Because the interannual variability in such survey-based indicators is high and because diagnostics on fish stocks cannot be based on noise, our concern is to make use of what is continuous in time to obtain a reliable diagnostic. In this paper, we show how min/max autocorrelation factors (MAFs) can be useful for assessing the status of a fish stock. Indeed, MAFs will allow us to (i) summarize the multivariate indicator signals into orthogonal factors that are continuous in time, (ii) select those indicators that carry the major signal in time, and (iii) forecast stock status by modelling the time continuity of the MAFs. These different potential uses of MAFs in an indicator-based approach to assessment were illustrated with North Sea cod, for which a suite of biological and spatial indicators are available over a 21-year survey series.

Key words: Min / max autocorrelation factors / Time correlation / Survey-based indicators / Fish stock diagnostics

Corresponding author: mathieu.woillez@ifremer.fr

© EDP Sciences, IFREMER, IRD 2009

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