Sharks and Skates of Scotland Report: Flapper Skate (Dipturus intermedius)
An extract from the Sharks and Skates of Scotland Report.
Flapper Skate - Dipturus intermedius (Parnell, 1837)
Occurrence in Scotland: Present on the continental shelf and slope, with populations distributed across Scottish shelf seas. Higher abundances are reported along the western and northern coasts, while densities are much lower in the North Sea.
Synonym(s): Raja batis, Raja macrorynchus, Propterygia hyposticta, Raja intermedia, Raia gaimardi, Batis vulgaris, Dipturus flossada, Dipturus intermedia; Order: Rajiformes; Family: Rajidae
Common name: Flapper skate
AlphaID: 105869, 711846 TSN Code: 564126
Population status
Scotland and Northeast Atlantic: Increasing (Régnier et al., 2024a; Ellis et al 2024). While a population reduction of >80% is suspected to have occurred over the past three generation lengths (~104 years) due to earlier levels of exploitation and a reduction in its range (Ellis et al., 2024), recent evidence indicates the species numbers are increasing in recent years (Régnier et al., 2024a; Ellis et al 2024).
Conservation listings
- IUCN Red List: Critically Endangered (assessment 02 April 2021)
- CITES: Not listed
- CMS: Not listed
- OSPAR: Threatened and/or Declining Species
- Listed as a Priority Marine Feature in Scotland
- Scottish Biodiversity List
- Feature of Conservation Importance in England and Wales (FOCI)
- Species of Principal Importance in Wales and England (SPI)
- Protected species in Northern Ireland, under the Wildlife (Northern Ireland) Order 1985
- Listed on the UK’s ‘Prohibited Species’ list as documented in the ‘Written Record of fisheries consultations between the United Kingdom and the European Union for 2025’ for UK waters of ICES divisions 2a and Subareas 4, 6, 7 and 8 and for EU waters of Subareas 3, 4, and 6 to 10
- Listed on The Sharks, Skates and Rays (Prohibition of Fishing, Trans-shipment and Landing) (Scotland) Order 2012
- Prohibited under EU Regulation 2025/202
- Dipturus intermedius (as Dipturus batis; the common skate) is a feature of the Loch Sunart to the Sound of Jura and the Red Rocks and Longay Marine Protected Areas (MPAs) (Marine (Scotland) Act 2010)
- Qualifying species of Fair Isle, The Gant, Neban Point, Red Rocks and Longay and Firth of Lorn ISRAs
Range and distribution
Flapper skate are commonly linked with colder, more variable inshore waters (Frost et al., 2020; Garbett et al., 2023) and are more frequently recorded around northern Scotland, Ireland, and the northern North Sea, but also occurs further south, including Portugal, the Celtic Sea, and the Azores. Flapper skate are not found at Rockall. As data pre-2010 is combined for Dipturus intermedius and Dipturus batis, the data is presented for the “common skate complex”, unless otherwise stated.
ICES DATRAS records for ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) for 1960-2019.
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Six maps of the economic exclusion zone (EEZ) of Scotland showing locations of trawls where ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) were captured from 1960 to 1969, 1970 to 1979, 1980 to 1989, 1990 to 1999, 2000 to 2009, and 2010 to 2019. Red points represent trawl shoot locations in which ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) were captured. Between 1960 and 1979 records of ‘common skate’ were sparse and mostly concentrated in the northern North Sea. From 1980 to 1989 ‘common skate’ were recorded more frequently throughout the EEZ of Scotland on the continental shelf, with records west of the Outer Hebrides, in the north of the Minch, on the north coast of Scotland west and east of the Orkney Isles, around the Shetland Isles and in the north North Sea. From 1990 to 1999 records were more numerous and more widely distributed, covering much of the Scottish west coast extending to the edge of the continental shelf west of the Outer Hebrides and the northern North Sea. From 2000 to 2019 there were more records throughout the EEZ of Scotland on the continental shelf with highest density on the west coast and some records in the North Sea. A change in the number or distribution of records over time does not reflect a change in occurrence or abundance since data have not been corrected for effort.
Records for Flapper skate (Dipturus intermedius) from SIAMISS and deep-water fisheries surveys undertaken by Marine Directorate 1996 – 2019.
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Map of the economic exclusion zone of Scotland showing records for Flapper skate (Dipturus intermedius) from the Scottish-Irish anglerfish and megrim industry-science survey (SIAMISS) and deep-water fisheries surveys undertaken by Marine Directorate 1996-2019. Records are illustrated as green points and are located predominantly on the west and north coast of Scotland offshore and up to the edge of the continental shelf west of the Outer Hebrides and north of the Shetland Isles. There are fewer records in the northern North Sea.
Tag - recapture records for ‘the common skate complex’ (Flapper skate and/or Common blue skate combined) from the Scottish Shark Tagging Programme, the Glasgow Museums tagging programme and the UK Shark Tagging Prog data 1970 to 2025.
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Map of the economic exclusion zone (EEZ) of Scotland showing tag - recapture records for ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) from the Scottish Shark Tagging Programme, the Glasgow Museums tagging programme and the UK Shark Tagging Programme data from 1970 to 2025. Records are illustrated as blue points and are located in coastal waters off the western coast of Scotland and the coastal waters of Orkney and Shetland. These tag – recapture records provided by anglers and occasionally supplemented by reports of tagged animals captured in commercial fisheries are thought to be mostly Flapper skate (D. intermedius) and show tight clusters in places where angling and tagging have occurred, for example the Sound of Mull, the Firth of Lorn and the Sound of Jura.
Discard data for ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) from commercial fishing vessels for 2014-2018.
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Map of the economic exclusion zone (EEZ) of Scotland showing discard data for ‘the common skate complex’ (Flapper skate (Dipturus intermedius) and / or Common blue skate (Dipturus batis) combined) from commercial fishing vessels from 2014 to 2018. The EEZ of Scotland is covered by a grid dividing it into International Council for the Exploration of the Sea (ICES) rectangles. Data is filtered to exclude information in rectangles where three vessels or less operate. Values are presented as individuals per trip and represented as a heat map (blue is one and red is 160) for each rectangle in the grid. Small numbers of discards were recorded resulting in blue rectangles patchily distributed all around Scotland, Orkney, Shetland and on the Rockall Plateau. There were also records of low discards resulting in blue rectangles in the northern North Sea extending to the northern and northwestern edge of the continental shelf.
Habitat
Flapper skate are are primarily benthic, inhabiting continental shelf and slope habitats from nearshore waters to depths beyond 300 m (Neat et al., 2015; Pinto et al., 2016). Seasonal and ontogenetic depth-use has been documented, with large females frequenting shallow waters (25–75 m) in winter, while most individuals occupy deeper trench systems (100–200 m) during summer (Thorburn et al., 2021). Habitat use is associated with sandy and muddy substrates, as well as mixed shell–gravel grounds (Benjamins et al., 2018). Egg deposition occurs in specific shallow coastal areas, confirmed through scientific surveys and citizen science photographs (Dodd et al., 2022, Mawer et al., 2025, Phillips et al., 2021). Resting behaviour, which involves flapper skate settling on the seabed for prolonged periods (Pinto et al., 2016), makes them significantly more vulnerable to dredging activity (Régnier et al., 2024b).
Biology and Ecology
Flapper skate are late-maturing and extremely long-lived. Males reach maturity at ~165 cm total length (TL), females at ~200 cm TL (Igelsias et al., 2010, Thorburn et al., 2023) at around 15-20 years of age (Régnier et al., 2021) with fecundity estimates of ≥37 eggs annually (Brander et al., 1981; Thorburn et al., 2023). Encapsulation and oviposition are concentrated in winter months, with egg cases requiring up to 18 months to develop (Benjamins et al., 2021; Dodd et al., 2022; Thorburn et al., 2023). Movement ecology studies reveal strong site fidelity and residency in sea lochs and trench systems, particularly for females, although transient individuals are also present (Neat et al., 2014; Lavender et al., 2022).
Human interactions
Their large size, late maturity and low fecundity combine to make Flapper skate extremely vulnerable to fishing pressure, with both eggs and juveniles at risk from being caught as bycatch in mobile fishing gear (e.g. Dodd et al., 2022). As a result, this species, grouped with Dipturus batis as the ‘common skate complex’, have historically experienced severe reductions in numbers and have been extirpated from parts of their former range (Brander 1981, Walker and Hislop 1998). Species-specific discard survival is poorly understood, but it has been previously shown that the ‘common skate’ can survive being trawled if they are released after capture (Little, 1995). Removal of the tickler chain from trawl gear can reduce the number of sharks and skates captured as bycatch, without impacting the catch excessively (Kynoch et al., 2015).
Flapper skate are a popular recreational angling species, with some areas (e.g. Argyll) attracting anglers from all over the world. Skate are caught on a strict catch and release basis. The Loch Sunart to the Sound of Jura Marine Protected Area (MPA) was proposed by the Scottish Sea Angling Conservation Network (SSACN). Tag recapture data for common/flapper skate in Argyll dating back to the 1970s, previously curated by Glasgow Museum and the UK and Scottish Shark Tagging Programmes, was assimilated by SSACN and used to justify their proposal. Sea anglers continue to contribute to the ongoing monitoring of the MPA via a PIT tagging and photo ID project (e.g., Régnier et al., 2024a). This data has been used to show that spatial management provides a benefit to Flapper skate, with numbers within the Loch Sunart to the Sound of Jura MPA increasing at a faster rate than Flapper skate numbers beyond the spatial measures (Régnier et al., 2024a).
In 2021 the first Flapper skate egg nursery in the world was identified in the Inner Sound of the Isle of Skye (Dodd, et al., 2021). The area was designated as Red Rocks and Longay MPA in 2022 and fishing with bottom contact mobile fishing gear and creels was banned inside the site to protect the eggs.
Note on 'the common skate complex', formerly Dipturus batis
Genetic research revealed in 2009 that what was formerly known as the common skate (Dipturus batis) was two distinct species, with Iglesias et al. (2009) naming the larger of these the flapper skate (Dipturus intermedia) and the smaller the blue skate (Dipturus flossada). These names have subsequently undergone some revision, and the most recently accepted nomenclature is the Flapper skate (Dipturus intermedius) and the Common blue skate (Dipturus batis) (Last et al., 2016). Because of this recent separation, “common skate” or “the common skate complex” still appears in some UK policy measures, which refers to flapper skate and blue skate combined. Also, historic information should be taken as referring to either flapper or blue skate. This relatively recent change creates uncertainty around the recorded data, as it is not clear which species (Flapper or Common blue skate) ‘common skate’ refers to.
References
Benjamins, S., Cole, G., Naylor, A., Thorburn, J., & Dodd, J. (2021). First confirmed complete incubation of a flapper skate (Dipturus intermedius) egg in captivity. Journal of Fish Biology, 99(3), 1192–1197.
Bache-Jeffreys, M., de Moraes, B.L.C., Ball, R.E. et al.,Resolving the spatial distributions of Dipturus intermedius and Dipturus batis—the two taxa formerly known as the ‘common skate’. Environ Biol Fish 104, 923–936 (2021).
Dodd, J., Baxter, J. M., Donnan, D. W., James, B. D., Lavender, E., McSorley, C. A., Mogg, A. O. M., & Thorburn, J. (2022). First report of an egg nursery for the critically endangered flapper skate Dipturus intermedius (Rajiformes: Rajidae). Aquatic Conservation: Marine and Freshwater Ecosystems, 32(10), 1647–1659.
Ellis, J. R., McCully-Phillips, S. R., Sims, D., Derrick, D., Cheok, J., & Dulvy, N. K. (2024a). Dipturus batis (amended version of 2021 assessment). The IUCN Red List of Threatened Species 2024: e.T203364219A256580832.
Ellis, J.R., McCully-Phillips, S.R., Sims, D., Walls, R.H.L., Cheok, J., Derrick, D. & Dulvy, N.K. (2024b) Dipturus intermedius (amended version of 2021 assessment). The IUCN Red List of Threatened Species 2024: e.T18903491A256581177. Accessed on 14 September 2025.
Frost, M., Neat, F. C., Stirling, D., Bendall, V., Noble, L. R., & Jones, C. S. (2020). Distribution and thermal niche of the common skate species complex in the north-east Atlantic. Marine Ecology Progress Series, 656, 65-74.
Garbett, A., Loca, S. L., Barreau, T., Biscoito, M., Bradley, C., Breen, J., Clarke, M., Ellis, J. R., Griffiths, A. M., Hannon, G., Jakobsdóttir, K., Junge, C., Lynghammar, A., McCloskey, M., Minos, G., Phillips, N. D., Prodöhl, P. A., Roche, W., Iglésias, S. P., Thorburn, J., & Collins, P. C. (2023). A holistic and comprehensive data approach validates the distribution of the critically endangered flapper skate (Dipturus intermedius). Journal of Fish Biology, 103(3), 516–528.
Griffiths, A. M., Sims, D. W., Cotterell, S. P., El Nagar, A., Ellis, J. R., Lynghammar, A., McHugh, M., Neat, F. C., Pade, N. G., Queiroz, N., Serra-Pereira, B., Rapp, T., Wearmouth, V. J., & Genner, M. J. (2010). Molecular markers reveal spatially segregated cryptic species in a critically endangered fish, the common skate (Dipturus batis complex). Proceedings of the Royal Society B: Biological Sciences, 277(1687), 1497–1503.
Iglésias, S. P., Toulhoat, L., & Sellos, D. Y. (2010). Taxonomic confusion and market mislabelling of threatened skates: Important consequences for their conservation status. Aquatic Conservation: Marine and Freshwater Ecosystems, 20(3), 319–333.
Last, P. R., White, W. T., de Carvalho, M. R., Séret, B., Stehmann, M. F. W., and Naylor, G. J. P. 2016. Rays of the world. CSIRO Publishing & Cornell University Press, Comstock Publishing Associates, vii + 790 pp.
Lavender, E., Aleynik, D., Dodd, J., Illian, J., James, M., Wright, P. J., Smout, S., & Thorburn, J. (2021). Movement patterns of a critically endangered elasmobranch (Dipturus intermedius) in a marine protected area. Aquatic Conservation: Marine and Freshwater Ecosystems, 32(2), 348–365.
Loca, S. L., Houghton, J. D. R., Garbett, A., Thorburn, J., Ó Cadhla, O., Clarke, M., Hannon, G., Pothanikat, L., Mayo, P., Gallagher, R., Hoppner, M. D. J., & Collins, P. C. (2025). A research toolbox for regional data collection to support the conservation of large batoids: a case study on the Critically Endangered flapper skate (Dipturus intermedius). Conservation Science and Practice
Mawer, R., Dodd, J., Thorburn, J., Burns, D. M., & Bailey, D. D. (2025). Using citizen science photographs to identify reproductive events in an oviparous elasmobranch. Journal of Fish Biology
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Philips, N., Garbett, A., Wise, D., Loca, S. L., Daly, O., Eagling, L., Houghton, J. D. R., Verhoog, S., Thorburn, J., & Collins, P. (2021). Evidence for an essential fish habitat for critically endangered flapper skate (Dipturus intermedius) off Orkney. Journal of Fish Biology, 99(4), 1213–1217.
Régnier, T., Dodd, J., Benjamins, S., Gibb, F. M., & Wright, P. J. (2021). Age and growth of the critically endangered flapper skate, Dipturus intermedius. Aquatic Conservation: Marine and Freshwater Ecosystems, 31(9), 2381–2388.
Régnier, T., Dodd, J., Benjamins, S., Gibb, F. M., & Wright, P. J. (2024a). Spatial management measures benefit the critically endangered flapper skate, Dipturus intermedius. Aquatic Conservation: Marine and Freshwater Ecosystems, 34(4), e4150.
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Thorburn, J., Cole, G., Naylor, A., Garbett, A., Wilson, K., James, M., Dodd, J., Houghton, J., & Collins, P. (2023). Preliminary insight into the reproductive status of the flapper skate (Dipturus intermedius) using in-field ultrasonography and circulating hormone concentrations. Endangered Species Research, 52, 97112.
