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ESR 52:97-111 (2023)  -  DOI:

Preliminary insight into the reproductive traits of the flapper skate Dipturus intermedius using in-field ultrasonography and circulating hormone concentrations

James Thorburn1,2,7,8,*, Georgina Cole3, Adam Naylor3, Amy Garbett2, Kirsten Wilson4, Mark James1, Jane Dodd5, Jonathan D. R. Houghton2,6, Patrick C. Collins2,6

1Scottish Oceans Institute, University of St Andrews, KY16 8LB, UK
2 School of Biological Sciences, Queen University Belfast, 19 Chlorine Gardens, Belfast, Co. Antrim BT9 5DL, UK
3Royal Zoological Society Scotland, Edinburgh Zoo, Edinburgh EH12 6TS, UK
4MRC Centre for Reproductive Health, University of Edinburgh, EH16 4TJ, UK
5NatureScot, Cameron House, Albany Street, Oban PA34 4AE, UK
6Queen’s University Marine Laboratory, 12-13 The Strand, Portaferry, Co. Down BT22 1PF, UK
7Present address: Edinburgh Napier University, Sighthill, Edinburgh, EH11 4BN
8Present address: Centre for Conservation and Restoration Science, Edinburgh Napier University, Edinburgh, EH11 4BN
*Corresponding author:

ABSTRACT: Due to global population declines, there is a pressing need for data on the life history traits of many elasmobranch species to support the development of species-specific management plans. A lack of information on the reproductive cycle of the Critically Endangered flapper skate Dipturus intermedius was recently identified as a hindrance to its conservation. To address this data gap, we combined non-lethal ultrasound and hormone analysis to investigate the size at maturity and reproductive cycle of the flapper skate in the Loch Sunart to the Sound of Jura Marine Protected Area off the west coast of Scotland. In-field ultrasound imagery revealed encapsulated eggs in utero and was used to determine the presence and size of ovarian follicles. Combining these images with levels of plasma testosterone, progesterone and oestradiol provided valuable insights into the timing of the reproductive cycle and maturity state of the flapper skate. This preliminary study suggests that male skate start to mature at 165 cm and females at 203 cm total length. Oestradiol appears to be the primary hormone controlling the female reproductive cycle and, along with ultrasound images, indicates that females lay pairs of eggs throughout a winter egg-laying season. Our study further highlights how non-lethal methods can be used to investigate the life history of oviparous elasmobranchs in the field. This information will support the identification of important life history groups and their associated habitats and contribute to the development of management strategies for these species.

KEY WORDS: Conservation · Management · Critical habitats · Non-lethal · Maturity · Reproductive cycle · Rajidae

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Cite this article as: Thorburn J, Cole G, Naylor A, Garbett A and others (2023) Preliminary insight into the reproductive traits of the flapper skate Dipturus intermedius using in-field ultrasonography and circulating hormone concentrations. Endang Species Res 52:97-111.

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