In this study, we applied two approaches of capture enrichment in order to obtain genome-wide markers for assessment of population genetic diversity and structure of Calanus finmarchicus. For the first capture we tried, we developed a probes set based on the reference of a transcriptome. We performed the capture for one individual of C. finmarchicus. This generated some genomic data that we assembled together and used as a genomic reference to design a second capture probes set. With this new set of probes, we performed a capture to several individuals from several populations for C. finmarchicus and also the congeneric species C. glacialis. From these newly sequenced data, we were able to yield a high number of SNPs useful for population genomics studies. We further evaluate the usefulness of this method to other species with unusually large genome sizes and for which no or little genomic information is available.