Scampi fishing in the North Sea is contributing to a “largely invisible” environmental impact by unsettling carbon that has been stored in seabeds for millennia, according to scientific findings.
Read: The catch
A study conducted by the University of Exeter focused on the Fladen Ground, a vast muddy seabed located east of Scotland, which ranks among the North Sea’s most significant fishing areas.
In this region, crustaceans such as Norway lobsters, or scampi, are harvested using bottom trawling, a technique where nets are dragged across the ocean floor, sweeping up various marine species indiscriminately.
Replenish
The Fladen Ground, situated on a continental shelf, is an important long-term carbon storage area, playing a crucial role in regulating the global climate.
However, the muds in these seabeds differ in their carbon storage capacity, burial speed, and vulnerability to releasing stored carbon into the ocean-air system, according to researchers.
The research, part of the five-year Convex Seascape Survey, discovered that the Fladen Ground accumulates new carbon at a very slow rate.
This indicates that much of its carbon was deposited as far back as the last ice age.
Researchers noted that when bottom trawling disturbs the sediment, the levels of new carbon do not replenish swiftly, potentially affecting ancient carbon reserves.
Sediment
The study also revealed that when disturbed material settles back onto the Fladen Ground seabed, it contains less carbon compared to other muddy seabed areas that can accumulate new carbon at a faster pace.
The climate impact of bottom trawling, therefore, varies based on its location, as different muds respond differently to disturbance, the findings suggest.
Although scampi is often promoted as an environmentally friendly seafood option, Zoe Roseby, the study’s lead author, explained: “Many people don’t realise that Norway lobsters live in mud, or that catching them involves towing nets directly across the seabed.
“That makes the environmental cost of scampi largely invisible to consumers.”
Discussing different muds, Roseby stated, “Some areas of the seabed are still actively accumulating sediment and carbon today, whereas the Fladen Ground is a low-accumulation environment.
Seabeds
“Most of the carbon stored there was deposited at the end of the last ice age and is not being replenished in our lifetime.
“This means that modern trawl events can disturb sediments and carbon deposited several thousand years ago.”
She added that the Fladen Ground may not be the most climate-sensitive area to trawl.
“As it accumulates carbon so slowly and contains relatively refractory material, disturbing it may mobilise less reactive carbon than in other areas with carbon-rich muds.
“The broader message is that not all seabeds carry the same climate risk.”
Cycle
The study suggests that effective marine management should take into account not only the amount of carbon stored in seabed sediments but also the rate at which it is buried and its susceptibility to being released.
Callum Roberts, a co-author of the study and the lead scientist of the Convex Seascape Survey, stated: “For fisheries to be genuinely sustainable, we have to consider where fishing takes place and how different seabed habitats function in the carbon cycle.
“This isn’t an argument against eating scampi or against fishing itself.
“But if seafood is to be climate-smart, we need to think not just about what we catch, but how and where we catch it, and use smarter spatial management to avoid disturbing seabeds that are actively accumulating and efficiently burying more vulnerable carbon.”
The research, published in the journal Marine Geology, is part of a collaboration involving Blue Marine Foundation, the University of Exeter, and Convex Group insurance company, which aims to enhance understanding of the ocean and its continental shelves in the Earth’s carbon cycle.
This Author
Rebecca Speare-Cole is the sustainability reporter at Press Association.
