Combining multiple Bayesian data analyses in a sequential framework for quantitative fisheries stock assessment

This paper presents a sequential Bayesian framework for quantitative fisheries stock assessment that relies on a wide range of fisheries- dependent and - independent data and information. The presented methodology combines information from multiple Bayesian data analyses through the incorporation of the joint posterior probability density functions ( pdfs) in subsequent analyses, either as informative prior pdfs or as additional likelihood contributions. Different practical strategies are presented for minimising any loss of information between analyses. Using this methodology, the final stock assessment model used for the provision of the management advice can be kept relatively simple, despite the dependence on a large variety of data and other information. This methodology is illustrated for the assessment of the mixed- stock fishery for four wild Atlantic salmon ( Salmo salar) stocks in the northern Baltic Sea. The incorporation of different data and information results in a considerable update of previously available smolt abundance and smolt production capacity estimates by substantially reducing the associated uncertainty. The methodology also allows, for the first time, the estimation of stock- recruit functions for the different salmon stocks.