Geographic variation in sardine population traits: implications for stock assessment

Tese dout., Ciências e Tecnologias das Pescas, Universidade do Algarve, 2007

This study integrates information on geographical and temporal variability of body morphometry, maturity-at-length, growth and population dynamics, to describe population structure of sardine within the Atlanto-Iberian stock region and adjacent waters and assist the de nition of stock units. Biological information was collected regularly at main shing ports and in acoustic surveys within the Iberian Peninsula since the 1980s and more recently in the French Gulf of Biscay. Spatial variation of morphometric and biological characteristics was also analysed across most of the species' range using samples collected in 1999 - 2004. Morphometric and biological characteristics showed clinal variation across the northeast Atlantic and di ered between Atlantic and Mediterranean populations. These characteristics and population dynamics were homogeneous within the northern (east Cantabrian to northern Galicia), western (southern Galicia to southwestern Portugal) and southern (southern Portugal and the Gulf of Cadiz) regions of the Atlanto-Iberian stock. Di erences among regions were obtained in some analyses but did not provide evidence of population discreteness when combined with other information from the area. Most characteristics were homogeneous across the limits of the Atlanto-Iberian stock. Overall, the results emphasized the need to explore alternative scenarios of stock structure, particularly in relation to the northern limit, and to consider geographical variation in biological traits and sheries exploitation in future stock assessments

Instituto de Investigação das Pescas e do Mar (IPIMAR)