Trawling practices hit rock-bottom

A landmark study by the Marine Conservation Society (MCS) has found bottom trawling to occur in 98% of the UK’s offshore Marine Protected Areas (MPAs). Their newly released ‘Marine unProtected Areas report’ outlines the issue of this destructive fishing practice in areas of protected sea life and calls for its ban. With our oceans already under so much pressure from various anthropogenic threats, the protection of vital benthic habitats and the halt of destructive practices is key to ensuring the ocean’s prosperous future. 

Bottom trawl

What is bottom trawling?

Bottom trawling is a fishing method whereby heavily weighted nets are dragged along the seabed catching fish, shellfish and other bottom-dwelling organisms. Large catches make it a popular fishing method, but it is a highly destructive practice that scours the seabed and contributes to the release of carbon.

What’s the issue?

In the UK, only 5% of MPAs currently have a ban on bottom trawling which has been described as “equating to bulldozing a land-based national park” by members of MCS. 99% of the offshore MPA’s have experienced bottom trawling and dredging activities between 2015 and 2018, and vessels equipped to carry out these practices have spent 89,894 hours fishing along protected seabeds. These benthic environments play a crucial role in climate change mitigation via carbon sequestration with The Dogger Bank MPA, off the coast of Yorkshire, having the capacity to store enough carbon to offset 31,000 round trips from London to Sydney. As trawling of the seabed occurs, carbon stocks are released into the marine environment and eventually back into the atmosphere. These losses also lead to mitigation costs which in the UK have been estimated at around £9 billion.  

Common shore crab (Carcinus meanas)

Further from the release of carbon, a study has shown bottom trawling to reduce biomass, diversity and body size among demersal fish species. This in turn affects their foraging and feeding and leads to dietary shifts towards energy-poor prey. Dogger Bank, the UK’s largest sandbank underpins the entire North Sea ecosystem and provides a commercially and environmentally vital habitat for many demersal species such as flatfish, starfish, sand eels, crabs, clams, scallops and many more. These organisms also play an integral role in the marine food-web and provide a food source for predators such as porpoises, seals and dolphins. Professor Callum Roberts from Exeter University told the BBC: “What is left on the Dogger Bank today is a ghost of what was once there”. Many of the area’s key species are now on the endangered list, and, until recently, restoration efforts were completely neglected. Historically, small fishing vessels would catch a tonne of halibut per day. Nowadays, an entire fleet catches less than two tonnes per annum.

What can be done?

European flounder (Platichthys flesus)

The report highlights that despite once rich and biodiverse seabeds now resembling bare sands, shell and gravel, recovery is possible. Studies from around the world have shown a 21% biodiversity increase after offering full protection to MPAs, and, in the UK, these were shown to be more diverse and bigger after the halt of bottom trawling. 

A positive aspect of Brexit will be the UK Government’s opportunity to manage MPA fisheries without the previously required agreement of EU member states.

Success stories

On the Isle of Arran and Lyme Bay, benthic organisms have began to thrive once more after a ban on bottom trawlers and dredgers. Similarly, around the Isle of Man, Lundy and Skomer, scallop and lobster numbers have increased within fully protected MPAs.

As of February 2021, many key UK fishing sites have seen a ban on bottom trawling after environmental organisations such as Greenpeace and The Marine Management Organisation have taken action to cease bottom trawling activities in protected areas. “Now that we have left the Common Fisheries Policy, we are able to deliver on our commitment to achieve a healthy, thriving and sustainable marine environment”, comments The Environment Secretary George Eustice.

The UK government has also decided on a partial bottom trawling ban at the protected sites off the coast of Land’s End and Lincolnshire. Dogger Bay has also been afforded increased protection, and this could lead to the recovery of its impressive array of megafauna: halibut, flapper, skates, angel sharks, eels and turbot.

Angel shark (Squatina squatina)

The future

The establishment of the proposed bylaws to protect the UK’s key MPAs: Dogger Bank Special Area of Conservation, Canyons Marine Conservation Zone, South Dorset Marine Conservation Zone and Inner Dowsing, Race Bank and North Ridge Special Area of Conservation, is the first step towards the recovery of these ecologically important sites. It’s an effort to establish a “blue belt” of MPAs around UK seas and eventually afford protection to 38% of its waters.

The report outlines the way forward as the effective management of MPAs to aid recovery, ensure sustainable fishing practices and mitigate climate change. A complete ban on bottom trawling is the most effective way of ensuring these changes occur, and these actions need to engage local communities which depend on marine resources. Permit conditions on fishing licenses and the introduction of remote real-time monitoring on fishing vessels have been proposed as potential management measures. These actions will allow UK offshore MPAs to:

  • Protect seabed species and habitats
  • Decrease carbon emissions
  • Provide sustainable food supplies
  • Afford protection to those with jobs in the fishing industry
  • Save money

The time to turn marine unProtected areas into Protected areas is now!

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