Surveying for flapper skate eggs

Last week it was announced that the critically-endangered flapper skate is to gain further protection with the extension of Red Rocks and Longay urgent Marine Protected Area (MPA) in the Inner Sound of Skye. In our latest blog, we take a closer look at recent fieldwork to survey the area.

NatureScot’s marine team were out and about this August and September to try and get a better handle on the distribution of boulder and cobble seabed habitats used by the flapper skate for laying and protecting their eggs during a lengthy 18-month gestation period.

When the Red Rocks and Longay MPA was designated on an urgent basis in March, interim management measures came into force, initially for 12 months. The survey work, part-funded by Marine Scotland, was undertaken to inform a detailed assessment of the area against the Scottish MPA selection guidelines. This advice will form part of a public consultation in February 2022 on the case for making Red Rocks and Longay MPA permanent.

Mapped sea-bed substrates around Longay and Red Rocks (Sgeir Dhearg), Inner Sound, Skye (Stewart et al., 2022). © Crown copyright [and database rights] 2021 OS 100017908. Reproduced with the permission of the British Geological Survey ©UKRI [2021]. All rights Reserved

The survey work was guided by detailed seabed habitat maps produced for the project by the British Geological Survey (BGS) using high-resolution multibeam data.

A drop-down video camera was used at more than 200 points in and next to the urgent MPA from a chartered scallop dive boat. The drop video equipment is simple and light and with careful deployment in the right conditions is a great way to get to know what lies below. The camera is protected within a stainless steel frame and the system lowered over the side of the boat until it ‘flies’ just above the seabed. The boat and camera frame were allowed to drift for ~5-10 minutes and footage of the sea floor was fed via an umbilical cable to a viewing screen in the wheelhouse in real time with accurate positioning. High definition video was recorded for later analysis.

The initial 10-day trip in August focussed on ensuring good coverage across the Red Rocks and Longay urgent MPA but also explored adjacent areas with similar habitat off the NE coast of Scalpay before venturing further afield, around Pabay to the south and Applecross to the north.

Armed with preliminary observations from the August survey, a short follow-up trip was completed at the start of September to fill some gaps and test the application of Remotely Operated Vehicle (ROV) survey techniques in the flapper skate egg-hunting quest.

NatureScot commissioned the specialist ROV services from Oban-based Tritonia Scientific Ltd. who conducted a previous dive survey of ‘Big Skate Rocks’ in 2020. This was the spot where approximately 100 flapper skate eggs were first recorded in late 2019 that ultimately led to the urgent MPA designation.

Two days of ROV survey work were undertaken. The sea conditions were a little lumpy on the first day but calm the following day and expert driving by the ROV and vessel skippers enabled the collection of some great footage. Significant numbers of skate eggs were recorded within the urgent MPA and on suitable habitat to the north of the original boundary.

Scottish Ministers have increased the size of the urgent MPA in the interim, in light of the additional flapper skate egg records, and applied the existing precautionary management measures to the extended area. The legislative orders come into effect today, December 16, 2021.

A summary report of the 2021 Red Rocks and Inner Sound of Skye fieldwork, covering both the August and September surveys, will be published in the early new year. This will also include observations of other seabed habitat Priority Marine Features (PMFs) such as flame shell beds and maerl beds.

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