Dolphin Head and North East of Farnes Deep Offshore Survey (Blog #2): BRUV (Baited Remote Underwater Video) footage
By Tom Tangye
Find out the latest from our offshore survey team. In their second blog post on their survey to the Dolphin Head and North east of Farnes Deep HPMAs, being undertaken in collaboration with colleagues from the Marine Institute of Ireland, they tell us about the work they've been doing with a BRUV (Baited Remote Underwater Video).
Firstly, what is a BRUV? BRUV stands for Baited Remote Underwater Video and BRUVS can come in many shapes and sizes. Their use can help build a better understanding of the local marine life.
Image: Photo of a BRUV showing the locations of the lights, cameras and bait box (© JNCC).
The BRUVs we are using on this survey have a camera system which you can lower to the seabed and leave to collect footage for a set amount of time. For this survey we are leaving the BRUVs for one hour. The BRUVs have underwater lights and two Go Pro 9 cameras in underwater cases that record life on or near the seabed. A bait box helps to lure any mobile marine life in the vicinity towards the cameras. The bait box is filled with fish (we have gone for herring, but you can use other bait). Marine life are lured to the cameras by the smell of the fish. After an hour, the BRUVs are recovered and brought back to the boat, the video footage is downloaded and the scientists on board can check out what marine life has come to investigate the bait.
Video clip: BRUV being recovered from the sea (© JNCC).
At Dolphin Head HPMA, our BRUV has been visited by many different species which have followed the scent of the herring bait. The video cameras have captured some majestic marine life of the English Channel.
Video clip: Cuttlefish (© JNCC).
We have had a few curious cuttlefish come and check out the BRUV. The common cuttlefish is one of the largest in the world and can grow to about 0.5 m in length. It is found all around the UK. In the video clip, you can see the two fins that run down the side of the cuttlefish's body – these help the creature manoeuvre and swim. Cuttlefish have eight arms with multiple rows of suckers and two long tentacles that are kept tucked away whilst not using them for hunting. They are infamous for being able to change skin colour and texture to blend in with their surroundings. As you can see in the footage, they are experts at camouflaging themselves to match the seabed.
Video clip: John Dory (© JNCC).
In this video clip, you find the unmistakable John dory fish popping in to say hello. Can you spot their friend? The John dory are stealthy hunters and often stalk their prey (mostly small fish) head on, their slim profile helping them sneak up on their prey.
Video clip: Conger eel (slow motion) (© JNCC).
Conger eels are mostly nocturnal and come out to hunt at night. The one seen in our BRUV footage was filmed at night, the smell of the bait luring it to come and investigate. Conger eels can grow up to 3 m long, and when they are mature, aged between 5 and 15 years old, they swim out into the deep Atlantic Ocean to spawn. Their spawning grounds are believed to be somewhere between the Azores and Gibraltar (3,000 to 4,000 m depth). When spawning, females are estimated to release between 3 and 8 million eggs before dying.
Nursehound (Catshark family)
Video clip: Nursehound (catshark) (© JNCC).
Nursehounds live close to the seafloor, usually preferring rougher, rockier areas, and can grow to over 1.5 m in length. The females lay one or two egg cases during spring and summer. These are similar to the ‘mermaid’s purses’ laid by skate and ray species.
Scad and Tope
Video clip: Scad and tope (© JNCC).
You can see a small shoal of scad, also known as horse mackerel, at the start of this video clip. Despite the name, they are not closely related to Atlantic mackerel. The name 'horse mackerel' possibly originated from an untrue belief that other small species of fish would ride on their back as they swim through the ocean (www.britishseafishing.co.uk/scad/). Scad generally grow to around 25 cm in size, but have been known to reach 70 cm and weigh about 2 kg. They are an important food source for many fish and seabird species.
Just before the end of the clip, a tope appears. Tope are a slim torpedo shaped shark that grow to just over 1 m but can reach 2 m. Females give birth to live young and can have litters of between 6 to over 50 pups. They do not reach sexual maturity until about ten years old and potentially live up to 60 years.
Video clip: Thornback ray (© JNCC).
Finally, during a recovery of the BRUV, we got a fantastic clip of a thornback ray, resting on the seabed. Thornback rays can grow up to four feet from wing tip to wing tip and feed on crustaceans like crabs but have been known to feed on small fish and flat fish. The have horns and spikes which grow down the central part of the body and can grow out to the edges as the rays get older.
If you missed our previous blog post on this survey, you can catch up at the following link: Dolphin Head and North East of Farnes Deep Offshore Survey (Blog #1): Setting sail on our first HPMA offshore survey