RESULTS
3.1. PHASE 1 - DEFINITION OF TARGET TAXA AND ESTABLISHMENT OF REFERENCE DATABASES
Following a review of WoRMS and the Irish Biodiversity Data Centre databases, a total of 151 bivalve and 147 decapod species were determined to occur in Irish waters (supplementary Table S2 ). Among these species were 24 selected target species as well as 48 bivalve and 18 decapod closely related off-target species (i.e. same Order). The most relevant and appropriate gene commonly targeted for molecular species identification of these taxa was identified as the mitochondrial Cytochrome Oxidase I (COI) with some studies targeting the 16S rRNA gene and the PAPM gene (nuclear) . The COI gene was selected as the main gene of interest for this study as it is more widely studied and better represented via BOLD with more sequences present. While relevant DNA sequence data was available on public databases for all target species, no genetic data were available for 10/48 bivalve and 5/18 decapod species (supplementary Table S2 ). Of the gathered tissue material, barcoding and relevant DNA sequence data were obtained from 49 samples (encompassing 15 distinct species) (88% successful amplification/sequencing) (supplementary Table S3 ). Tissue DNA belonging toAequipecten opercularis (queen scallop) and Pecten maximus(king scallop) did not yield satisfactory results. As expected,Mytilus edulis, Mytilus trossulus and Mytilus galloprovincialis were not resolved to the species level using the COI gene. Overall, once previously available and newly generated DNA sequences were included, the dedicated reference database achieved coverage of 80% (for bivalves) and 70% (for decapods) of target species (supplementary Table S2 ).