Exploitation and Conservation Status of Rajiformes Species in the Western Mediterranean

Fisheries management requires the best scientific knowledge on the exploitation and conservation status of stocks. This is challenging for by-catch species, for which assessment data is more limited than for target ones. That is the case of chondrichthyan species, particularly vulnerable to fishing impacts due to their life history strategy. In the present study we use an integrative approach, including innovative assessment methods and genetic diversity analysis, to assess the exploitation and conservation status of six skate species in the Balearic Islands (western Mediterranean). Among them, Raja clavata is the most important species in terms of abundance and the unique with a time series of landings long enough (from 1964) to be used in production models. Thus, these data, along with information from bottom trawl surveys (since 2004) are used to apply CMSY++ and Bayesian state-space Schaefer production models to assess its exploitation status. For the rest of the species, the exploitation status is analysed with a novel production model, based on time series of abundance data from surveys (AMSY). The conservation status for all the analysed species is assessed by comparing the mitochondrial Cytochrome C Oxidase subunit I gene (COI) nucleotide diversity in the Balearic Islands populations against the COI genetic diversity benchmarks estimated for Elasmobranchii and Rajiformes species from sequences available in BOLDSystem. To do so, a small piece of pelvic fin from the specimens caught during the surveys was collected. The tissue is processed in the laboratory to extract DNA, amplify COI sequence through Polymerase Chain Reaction and for sequencing. Sequences are analysed to estimate nucleotide diversity of Balearic Islands populations of the studied species. Results show that exploitation and conservation status can present different patterns for the same species. That is the case of R. clavata, which showed that the stock is currently overexploited, even though