Underwater cameras around the Isles of Scilly have given scientists a glimpse of how sea life can thrive in well-protected UK waters.
Despite widespread degradation of UK seas from destructive fishing, pollution, and climate change, the waters surrounding the Isles of Scilly appear to be bucking the trend.
This new study used baited underwater cameras and found the Isles of Scilly's waters support vibrant marine life including sharks, lobsters, octopuses and bluefin tuna.
The researchers say these relatively low-cost camera systems could be used to improve the monitoring and effectiveness of Marine Protected Areas (MPAs) – helping restore thriving seas around the UK.
The study was led by the University of Exeter, working with the Isles of Scilly Inshore Fisheries and Conservation Authority and Natural England.
"The richness and variety of marine life around the Isle of Scilly is wonderful to see," said Dr Owen Exeter, from the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.
"Our cameras recorded nearly 12,000 individual animals, from 64 species, including large populations of commercially targeted species such as lobsters and small sharks.
"We also saw bluefin tuna – which have recently returned to UK waters after largely disappearing due to overfishing.
'Healthy seas'
While the site isn't entirely untouched by human activity, the team describes it as one of the UK's most 'near-natural' marine ecosystems – largely protected from destructive practices such as bottom trawling, and with relatively low human impact due to the archipelago's small population and well-managed fisheries.
"These waters haven't recovered from severe damage – they've remained in comparatively good condition. By studying ecosystems like this, we can start to understand what a healthy UK marine environment should look like. This gives us a crucial reference point as we work to restore degraded areas elsewhere," continued Dr Exeter.
The findings suggest that complex seabed habitats, such as reefs and mixed sediments which can be damaged by bottom trawling, host especially high biodiversity, underlining the importance of protecting these areas.
Bottom trawling – a focus of the recent David Attenborough film, Ocean - is permitted in some UK MPAs but the government is considering extending a ban to more areas .
'Great option'
The cameras used in the study, known as Baited Remote Underwater Video Systems (BRUVs), offer a powerful tool for assessing whether MPAs are delivering measurable benefits for marine biodiversity when bottom trawling is excluded.
"MPAs are only as effective as the protections and monitoring in place to support them," said Dr Kristian Metcalfe, Associate Professor in Marine Conservation Science at the University of Exeter.
"These camera systems allow us to track changes in species diversity and abundance over time, giving us vital evidence on whether conservation measures are working.
"They're non-destructive, relatively inexpensive, and scalable – making them a great option for regular biodiversity assessments across large areas of our coastal seas."
Jules Webber, from Natural England, said: "We have been really pleased to support Owen's work for this PhD.
"BRUVs can provide invaluable evidence to help improve our understanding of the condition and effectiveness of our Marine Protected Areas.
"This project has really demonstrated how BRUVs could be a consistent, non-invasive and low-cost way to monitor these critical marine ecosystems long-term."
The research has informed the Isles of Scilly being designated as an Important Shark and Ray Area (ISRA) .
This recognition highlights the region's significance for four shark species (primarily catsharks, with supporting species nursehounds, blue sharks, and porbeagle sharks) and provides an important tool to guide conservation and management efforts.
ISRAs are not regulatory or restrictive, but rather reflect areas of ecological interest and serve as a science-based framework to inform decision-making and strengthen the case for future funding and conservation initiatives.
The camera systems used in the study, developed by Blue Abacus , have two cameras that can be used estimate the size of individuals, providing rich ecological data for long-term marine monitoring.
Dr Exeter's work was funded by a Natural Environment Research Council GW4+ Doctoral Training Partnership PhD Studentship – a case partnership between the Isles of Scilly Inshore Fisheries and Conservation Authority and Natural England.
The paper, published in the journal Ecological Applications, is entitled: "Application of spatially robust stereo baited remote underwater video sampling for quantifying fish assemblages in UK marine protected areas."
