A new minibarcode assay to gacilitate species identification from processed, degraded or historic ray (batoidea) samples

Rays (Batoidea) are among the most threatened groups of vertebrates. Slow growth and low fecundity make many species vulnerable to overfishing, but increased demand for gill rakers in traditional Chinese medicine and elasmobranch meat means exploitation continues. In response, protection has increased, with manta and devilrays (Mobulidae) and sawfishes (Pristidae) now listed on Convention on International Trade in Endangered Species (CITES). This protection requires an accurate assay for species identification, even when parts of the body have been removed or products have been processed. Therefore, we developed and tested a new COI minibarcode to identify ray species among processed samples. This assay was tested on 25 samples from across four batoid orders and showed consistent amplification. In 68% of cases, a correct top match was identified on GenBank and BOLD, but its accuracy should be much higher (particularly due to extensive taxonomic revisions in this group). Bioinformatic analysis of existing sequences also showed 81% of minibarcodes were matched back to a single species and 100% correctly back to all other taxonomic ranks. This increased to 91% when only including records published in the previous 2 years (that should help to account for recent taxonomic revisions). Analysis of skate ‘wings’ and cooked samples was highly successful, allowing the unambiguous identification of species. These results suggest this minibarcode will be highly useful in identifying ray species and could have a range of applications from the analysis of processed products to investigations of environmental DNA, making them an effective tool in the conservation of endangered batoids.