First report of an egg nursery for the Critically Endangered flapper skate Dipturus intermedius (Rajiformes: Rajidae)

Abstract

1. This study provides the first report of an egg nursery for the Critically Endangered flapper skate Dipturus intermedius and a description of the habitat, thus contributing towards our understanding of essential habitats for the species. 2. In total, 1,395 flapper skate egg cases were recorded (accounting for overlapping surveys) in two egg case collection dives (n = 67 egg cases), one photogrammetry dive (n = 10 egg cases), 509 drop-down video (DDV) camera drifts (n = 510 egg cases) and 18 remote operated vehicle (ROV) flights (n = 1,031 egg cases), carried out in the Inner Sound on the west coast of Scotland from 2018 to 2021. All of the egg cases were found on a shallow bedrock plateau between the Isle of Scalpay and a deep (>100 m) water channel between the Isle of Longay and the Crowlin Islands. Egg cases were observed on a cobble/boulder reef between 25 and 58 m depth, with a modelled annual temperature range of 9-12 C, modelled current speeds up to 0.2 m À1 , a rugosity index of 1.7 and low levels of sedimentation.3. Flapper skate egg cases are large and the incubation period is protracted (18 months), making them potentially vulnerable to anthropogenic disturbance.A description of the habitat where egg cases were observed in this study will help inform the search for egg nurseries for this Critically Endangered species elsewhere. Targeted DDV, ROV and scuba diving surveys will support this search in areas where suitable bathymetric and hydrodynamic conditions are identified.4. Safeguarding egg nurseries is essential for successful conservation. Protection should involve the designation of egg nurseries as Marine Protected Areas where activities that are likely to damage or alter seabed habitats are managed.

Benthic animal-borne sensors and citizen science combine to validate ocean modelling

“…Specific actions to support recreational mark-recapture angling (such as the provision of passive integrated transponder tags and scanners to skippers) and the establishment of a photo-identification database (‘SkateSpotter’) have also helped to connect anglers with scientific research and provided a means for anglers to submit and receive data 37 , 42 . Angler mark-recapture records recorded on SkateSpotter from individuals’ time at liberty, alongside the return of tags from recaptured skate by recreational anglers, underpinned the work presented here alongside previous studies 36 , 38 – 41 , 43 , and partnerships between NatureScot, researchers and other stakeholders continue to support ongoing research on skate in the region 55 , 56 . This demonstrates the value of fostering positive relationships between stakeholders and the important contributions that recreational anglers can make to scientific research.…”

Seamount coral reefs are egg case nurseries for deep‐sea skates

“…Meyer et al ., 2019) or may be reported from selected transects and/or localised areas where egg cases are concentrated ( e.g . Henry et al ., 2016), or from a combination of observational methods and strategies (Dodd et al ., 2022). These sources of variability mean it is difficult to define a threshold that is generally appropriate across different seabed features and survey tools, and highlights a need for a flexible interpretation of the density criterion used to define a nursery.…”

The distribution of the juvenile stages and eggcases of skates (Rajidae) around the British Isles

“…Holden (1975) considered that female R. clavata congregated in parts of The Wash to spawn, whereas Williamson (1913) reported large numbers of skate eggcases on the Aberdeen Bank (North Sea). More recently, Dodd et al (2022) provided information on spawning areas of D. intermedius off western Scotland.…”