SUMMARY

• Main Authors: Victoria Ortiz De Zárate, Michel Bertignac
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.524.3704; http://www.iccat.int/Documents/CVSP/CV054_2002/no_5/cv054051438.pdf

In this study, an attempt is made to estimate natural mortality rate for North Atlantic albacore. We implement a spatially aggregated tag-attrition model to analyse the results of an albacore tagging experiment conducted in the Bay of Biscay from 1988 to 1991. The model predicts probabilities of the possible fates of tagged fish and the tags that they carry. The model includes several parameters consisting of catchabilities by fleets involved in recaptures and a combination of natural mortality plus emigration from the study area. Model fitting is carried out by finding the maximum of a multinomial likelihood function. Effect of reporting rate values on the estimations are evaluated and several hypothesis on the pre-mixing period of the tagged fish population among the total albacore population are made. Depending on model formulations selected, attrition rate of 0.56 and 0.84 per year are estimated. Although those estimates are reasonably consistent with previous studies, several uncertainties still limit our interpretation of the results in terms of natural mortality rate. RÉSUMÉ