Résumé
“Swordfish (Xiphias gladius) is managed in the Indian Ocean by the Indian Ocean Tuna Commission (IOTC) and is of special economic importance. Currently IOTC estimates the swordfish stock size using SS3 models based on CPUE which can have many biases. In this study, we present our Close-Kin Mark Recapture (CKMR) approach on Indian ocean swordfish. For CKMR, related individuals are identified from their genotypes and their number and pattern is used for abundance estimation. In our study, over 2 030 individuals were genotyped from around the Indian Ocean using Single Nucleotide Polymorphism (SNP) markers. With these analyses, we were able to find one parent-offspring pair (POP) and one half-sibling pair (HSP). With this information, we estimate the number of adult swordfish was around 1 434 880 individuals in 2009 in the Indian Ocean. However, as a very low number of POPs was obtained from the analysis, we are not able to calculate a robust confidence interval or a strong CV. For improved statistical confidence, we estimate that we will need to obtain around 50 POPs/HSPs, which will require sampling about 15 000 individuals.