• Client: Blue Marine Foundation

• Year: 2024

• eftec Team: Ian Dickie, Agata Makowska, Natalya Kharadi, Claudio Contento,

• Full report: Accessible here

Recognising the importance of the marine environment, a “three nautical mile limit” (3nm) from the Scottish coast prohibited bottom trawling and dredging between 1886 and 1984. The ban was repealed in 1984 due to continued pressure from the commercial bottom trawl industry. Since then, inshore fish stocks have plummeted along with the numbers of active fishermen around its coast. Fishers are having to fish harder for less, as habitats have been reduced to a fraction of their historic extent.

Our Seas Coalition is campaigning for the re-introduction of a modern inshore limit that protects the 3nm area under pressure from bottom-towed fishing. Blue Marine Foundation, a member of Our Seas Coalition commissioned this study to understand the impacts of re-introducing a 3nm limit around the Scottish Coastline. This is the first study to primarily focus on impacts of bottom-towed fishing on ecosystem services within the 3nm area, rather than across the whole Exclusive Economic Zone.

Such a limit will have both potential benefits such as enhanced carbon sequestration, and economic and ecological gains for the static gear sector, and potential costs like losses to the bottom-towed fishing sector.

The analysis used a natural capital approach to collate published evidence, incorporate advice from marine ecosystem services experts, and assess the current state of policy against the expected changes that would result from a closure to bottom-towed fishing in the 3nm area. Using a natural capital approach makes the impacts of a policy or intervention easier to identify and communicate by distinguishing between the changes in the quantity and condition of natural capital assets and flows of benefits they provide.

Based on assumed future trends in asset size and condition and ecosystem services, the present value of benefits was calculated to give an asset value under two scenarios:

• Business as Usual (BAU) - continuation of current bottom towed fishing activities, and no other changes in marine management, and;

• Protection Scenario - complete cessation of bottom-towed fishing within the 3nm area, and no other changes to marine management. This scenario would increase the area that is fully protected from bottom-towed fishing from 4,300 km²  to 30,800 km² (i.e., the entirety of the sublittoral habitats in the 3nm area).

Comparing the BAU to the Protection Scenario showed that:

• A five-fold increase in present value of the total net monetary benefits over 20 years (from around £900 million in BAU to £3.6 billion in the Protection Scenario). In overall value terms, the expected loss in value from bottom-towed fishing was offset by the recovery of marine habitats to provide other ecosystem services (e.g., carbon sequestration).

• A 257% increase in habitat area within the 3nm boundary receiving protection relative to the BAU, supporting gamete dispersal and pest and disease control.

• A doubling of the net carbon sequestration within the 3nm area (i.e., carbon sequestered by subtidal habitats and net of emissions from sediment disturbance), reflecting the recovery of subtidal sediments. This is expected to be an underestimate, as the potential expansion of areas of vegetated habitats (e.g., kelp) was not quantified.

• Potential increase of around 50% of static gear fish landings (i.e., catch brought to shore by nets, traps and pots) from areas previously under pressure from bottom-towed fishing.

The assessment shows that the expected losses in fishing activity from the protection of Scotland three-nautical mile area would be offset by the recovery of marine habitats and their ability to provide benefits to the economy and society. Although a net benefit to society is estimated, further analysis of implementation and management cost would be informative.

A valuable output from the assessment was the asset register, detailing habitat areas within the 3nm area at the finest resolution possible with available evidence. This was a key data input to identifying the significance of closing the 3nm area to bottom-towed fishing and identifying material ecosystem services and benefits for inclusion in the assessment, and potential future supply of ecosystem services that could not be quantified in the assessment.

Blue Marine Foundation is advocating for a just transition away from unsustainable fishing practices to enable communities and livelihoods to thrive alongside restored seas. The approach used in this study can be applied during the development of future marine and fishery management plans and Impact Assessments to allow more informed and sustainable management of marine resources.

See our Fisheries Transition Analysis Framework commissioned by Blue Marine Foundation.