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Monitoring Critically Endangered Angel Sharks using Baited Remote Underwater Video Systems (BRUVS)

 Blog written by Jake Davies for Neptunic. Jake is a Save Our Seas Project Leader. 

https://saveourseas.com/project-leader/jake-davies

Angelsharks (Squatina squatina) are large, flat-bodied sharks that can reach 2.4m in length, belonging to the angel shark family (Squatinidae), which rank as the second most threatened family of elasmobranchs (sharks, skates and rays) in the world. Angelsharks are normally found submerged in sandy habitats in coastal waters. Once common across the western British Isles, they are a rare species of shark that glide across the seabed with elongated fins. After suffering widespread decline across its range over the last century, there have been an increasing number of sightings of this rare species along the Welsh coast.

Working in collaboration with Angelshark Project: Wales, Angelshark Project: Canary Islands and Natural Resources Wales, ‘Guardian Angels’ project; funded by Save Our Seas Foundation, aimed to trial the use of BRUVS to monitor Angelsharks. Providing another potential tool to better understand the Critically Endangered Species.

During the course of it, BRUVS were tested in the Canary Islands, where Angelsharks are relatively common, and were be placed in areas of higher and lower Angelshark abundance. They were deployed during day and at night to detect potential diurnal variation, as the species is known to be more active during the hours of darkness. BRUVS were deployed in Wales at key areas identified by the Angel Shark Project: Wales. BRUVS may be another useful tool for gathering data about Angelsharks when covering large areas and in regions where visibility is too low to undertake dive or snorkel surveys.

Project findings:

After spending days and nights out on the water deploying BRUVS, a total of 101 hours of exciting footage was recorded and reviewed.  A total of 48 species were recorded from squid to sharks. For elasmobranchs, a total of 5 species were recorded which included 2 ray species (spotted ray (Raja montagui) & thornback ray (Raja clavata) and 3 shark species from the common lesser spotted catsharks (Schyliorhinus canicula), to the larger less common Tope or schooling shark (Galeorhinus galeus). Importantly the BRUVS didn’t just pick up adults but also recently born pups as well as sub-adults which was exciting to see. However, no Angelsharks were recorded during the deployments off the Welsh coast.

Tope

Tope pup (Galeorhinus galeus) (Top left) Thornback Ray (Raja clavata) (Top right) Lesser Spotted Catshark (Scyliorhinus canicula) (Bottom) © Jake Davies

To trail the BRUVS we headed out to La Graciosa marine Reserve where we joined the Angel Shark project: Canary Islands team on their acoustic tagging campaign. La Graciosa is a small island North of Lanzarote and is located within the Reserva Marina del Archipiélago Chinijo. The reserve spans 70,700 hectares and makes it one of the largest marine reserves in Europe.

 BRUVS equipment flat packed and ready to be packedImage result for copyright symbolJake Davis

A total of 30 BRUVS were deployed, of which 9 were deployed at night. A wide range of species were captured with eagle rays, stingrays, breams, moray eels and white trevally to name a few. Excitingly, Angelsharks were recorded on the BRUVS, not once but on 3 different occasions. One of the observations occurred at a site where Angelsharks are rarely seen and none were observed during the Angelshark survey that day. Only male Angelsharks were observed on the footage, which can be explained as it's considered Angelshark mating season therefore, males tend to be more active in search of females.

 

Snapshots taken from the BRUVS: A Grey Triggerfish (Balistes capriscus) & Goldentail Moray (Gymnothorax miliaris), B) Common Eagle Ray (Myliobatis aquila), C) Rough tail Stingray (Dasyatis centroura), D) Angelshark (Squatina squatina) © Jake Davies

Teaming up for filming:

As part of promoting the work wider we teamed up with Wildlife Cinematographer Ollie Putnam and shark ecologist Hannah Milankovic to reveal more about the project and methodology of using BRUVS. Joining on a weekend of surveys off the Welsh coast they were able to get involved in deploying BRUVS and reviewing footage as well as filming the process to reveal more about the project.

To find out more about the projects:

Save Our Seas Foundation - https://saveourseas.com/project/guardian-angels/

Angel Shark Project: Wales -  https://angelsharknetwork.com/wales/

Angel Shark Project: Canary Islands - https://angelsharknetwork.com/canaryislands/

 

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