Understanding the pattern of population structure and species dynamics in time and space is essential for efficient fisheries management and the long-term sustainability of fish stocks. Elasmobranchs (sharks and rays) are a data-deficient group, and particularly vulnerable to fishing pressure given their highly conserved life strategies and limited population rebound potential at ecological timescales. In the NE Atlantic, concern on the status of some elasmobranch species and the lack of clear data regarding stock structure and dynamics have led to severe restrictions on catches and regulation of fisheries operations as precautionary fisheries management.

Genetic stock identification is a widely used method of relevance to fisheries management and conservation. Several studies have been conducted for NE Atlantic elasmobranchs based on neutral molecular markers, but have generally showed weak or no evidence of population structure. However, neutral markers may have limited power in detecting genetic differentiation in species with large effective sizes and moderate to high gene flow, such as many marine species. In such cases, markers under selection may provide better resolution and detect cryptic population differentiation at smaller spatial scales.

Here, genes associated with adaptive immunity will be assessed as alternative, cost-effective molecular markers to study the population structure of exploited NE Atlantic elasmobranchs. Immunity genes are under strong selective pressure by local pathogen communities, and often show stronger among-population genetic differentiation than neutral markers. The effect of two ecological traits, habit and habitat, on the genetic diversity and divergence at adaptive immunogenes will also be studied across elasmobranch lineages, and the scale at which among-population differentiation occurs will be inferred to guide initial management and conservation actions in data-deficient taxa. Furthermore, the above data will be complemented with new transcriptome sequencing of immunity-relevant tissues to complement available chondrichthyan datasets and improve the knowledge on the evolution of the vertebrate adaptive immune system.

Several arrangements have been made to insure the successful execution of the research plan, and an efficient knowledge transfer to relevant stakeholders. Sample collections are already available for all target species considered, as well as preliminary transcriptomic data from one species (Annex I). The team includes experienced elasmobranch researchers focusing on population genetics, biology, ecology and fisheries management, as well as immunobiologists, evolutionary biologist and bioinformaticians. Project results will improve current stock assessment of vulnerable elasmobranchs and team members are directly involved in regional fisheries management organisations (i.e. ICES) providing management advice to the EU on elasmobranch fisheries.