A genetic tool to help monitor sharks and skates in the North-east Atlantic

To establish a practical genetic monitoring tool for rapid, high-throughput genotyping that is accessible to researchers monitoring flapper skate and spurdog. These standardised marker panels will produce additive datasets in perpetuity, providing invaluable repositories suitable for temporal and cross-laboratory comparisons and will permit ongoing monitoring across multiple legislative authorities.

As high-value fisheries species, many north-east Atlantic elasmobranchs have been significantly impacted by targeted fishing and by-catch. As a consequence of their low intrinsic rate of increase, recovery of their populations can be very slow and in some species a significant proportion of their valuable genetic resources may have been lost forever. This makes genetic monitoring to assess the variability and connectivity of populations essential components of management for identifying the best practices that are likely to benefit elasmobranch conservation.

Marine protected areas are increasingly used as a tool to promote conservation across locations chosen for their habitats that are likely to be important to species of conservation concern. Elasmobranchs in the north-east Atlantic have site-associated behaviours, which means they stand to benefit greatly from marine protected areas, as will other species in the local ecosystem in which these top predators play a pivotal role. The ‘Loch Sunart to Sound of Jura’ marine protected area in west Scotland was chosen to protect the flapper skate, one of two ‘common skate’ species now recognised as endangered. Large numbers of skate in the area indicated important habitats and it was hoped that protecting this population would allow connectivity with others, as the larger the interbreeding unit, the better it is able to maintain the valuable genetic diversity that allows the species to adapt to environmental change. The spurdog, an endangered elasmobranch, is incidentally protected in the same protected area and its genetic health and connectivity also need monitoring. Our initial work suggested that the flapper population in the marine protected area comprised individuals with unique maternally inherited genetic components. This could reflect that females are not breeding or travelling much beyond the protected area and that they are more isolated than initially hoped, thereby limiting the area’s effectiveness as a conservation tool that maintains genetic variation as part of a regional population. Genetic markers with a higher resolution suggest there is some connectivity with other populations, but this requires further investigation and the results need to be made capable of being interpreted by future generations of conservationists. Assessing variation with a monitoring tool of a smaller panel of highly informative flapper skate and spurdog markers should allow new technologies to standardise genetic assessments, removing any bias of individual laboratories and operators. Placing samples and data in a free-access national repository will encourage the formation of larger working groups to monitor further flapper skate and spurdog populations and make it possible to determine the effectiveness of marine protected area management.

• To identify a subset of the most informative genetic markers for each species, derived from larger genome datasets, and develop a monitoring tool that will enable kinship, genetic diversity, population connectivity and adaptive patterns to be analysed.
• To evaluate the performance of the new monitoring tool for different tasks compared with alternative genome-wide markers and to trial the monitoring tool on DNA sources of poor quality/quantity, such as flapper skate egg cases and skin mucus and historic material. If successful, this will enable individuals to be linked to nurseries and sample sizes to be increased. Museum specimens may enable historical changes in genetic diversity to be assessed.
• Together with collaborating NGOs, to create a manual for consideration by policy-makers and elasmobranch conservation bodies, illustrating how this methodology can be used in conservation management and the monitoring of threatened species.
• To deposit a dataset based on available and new samples that will form the basis of an additive data repository for standardised genetic information about these species.