Researchers at the Lyell Centre for Earth and Marine Sciences, one of Heriot-Watt University’s flagship Global Research Institutes (GRIs), have created a new method for assessing the risk of different fishing gears on the seabed’s ability to capture and store organic carbon.
Better understanding of the carbon storage capacity of marine habitats could help efforts to mitigate the effects of climate change through fisheries management systems.
The method, named the CSA carbon extension, incorporates carbon attributes to the existing Marine Stewardship Council (MSC)—a non-profit organization that sets the standards for sustainable fishing—Consequence and Spatial Analysis (CSA) Framework and is recommended by Lyell Centre scientists to better establish the risk of fishing practices on organic carbon impacts.
Kate Morris, postgraduate researcher at the Lyell Centre said: “Our case study highlights that consideration of a habitat's ability to capture and store carbon, can and should be incorporated into existing management practices to evaluate and mitigate the risk of different fishing practices.”
An initial case study was conducted in the southern North Sea, selected as its habitat is generally representative of those across the UK EEZ (Exclusive Economic Zone). Scientists took the existing MSC CSA scoring methods of habitat productivity, defined as the proclivity of habitats to capture and store carbon dependent on its environmental conditions e.g., flat vs. rocky, seagrass vs. sand; and gear-habitat interaction, which measures the prevalence of marine biodiversity disturbance by unnatural factors, such as dredges; and incorporated organic carbon stock and carbon accumulation into the calculations.
By using this method, researchers found changes in outcomes that affected the overall risk factor of different environments. For example, seagrass overtook densely packed mudflats as the highest risk habitat for carbon disturbance through fishing, whilst the risk levels on near-shore sand lessened.
Scientists believe that adoption of the CSA carbon extension within the existing scoring frameworks can inform fisheries management measures that support the sustainable, and climate conscious development of UK fisheries, ensuring practices can meet increasing global nutritional needs while reversing declines in marine biodiversity.
Kate Morris said: “Wild capture fisheries are of huge economic and social importance however to fully understand the impact that towed fishing gears, such as trawls and dredges, have on the global CO2 budget requires further study.”
“Our case study highlights that consideration of a habitat's ability to capture and store carbon, can and should be incorporated into existing management practices to evaluate and mitigate the risk of different fishing practices.”
“For example, saltmarshes in the UK play an important role in the oceanic carbon cycle and aren’t currently targeted by fishers. However, should they become economically viable fishing grounds, due to extraction of seabed resources or sea level rise, our method provides a better understanding of the potential risks different fishing methods could have on this valuable carbon-storing resource.”
Professor Michel Kaiser, Co-Director of the Lyell Centre and co-author of the study, said: “The accuracy of habitat maps and fishing pressure data is vital to produce a comprehensive assessment of the impacts of fishing on carbon storage and capture in areas of the seabed subjected to a range of different fishing intensities.
“More in situ experimentation on exactly how fishing impacts carbon stores will inform more sustainable management practices in the future.”
The full paper, "Adapting the Marine Stewardship Council’s Risk-Based Framework to assess the impact of towed bottom fishing gear on blue carbon habitats”, was published in The Public Library of Science ONE journal on November 16, 2023.
