This work was funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs, grant G1100675). The authors are grateful to the Marine Scotland aquarium staff (Ben Williamson, Louise Feehan and Mark Paterson) for help in the experimental work. Hendrix-Genetix (formerly Landcatch Natural Selection) is also acknowledged for providing PIT tagged fish for the purpose of this project.Peer reviewedPublisher PD