Hidden havens: Shipwreck sites provide a sanctuary for marine life

A recent study by the University of Plymouth and Blue Marine Foundation reveals a significant ecological benefit of shipwrecks around the UK’s coastline. 

These shipwreck sites, estimated at around 50,000, have been acting as refuges for marine life, particularly in areas that are still open to destructive bottom towed fishing. 

Key insights

The research shows that shipwrecks, many of which have been on the seabed for over a century, are deterring bottom towed trawling, a method commonly used by fishers to secure catches.

This deterrent effect has preserved the seabed in and around shipwreck sites from the damage typically seen in heavily fished areas. The study found a striking contrast in marine life density between wreck sites and areas actively used for bottom towed fishing. 

Protected areas

On average, marine life density was 240% greater within wreck sites compared to actively trawled areas. This difference was even more pronounced within a 50m radius of the wrecks, where marine life density was 340% greater than control sites.

By contrast, in areas closed to trawling, the abundance of marine life was 149% greater than on wreck sites and 85% greater than the seabed surrounding the wrecks. This indicates that while shipwrecks offer significant protection, fully protected areas show even greater ecological benefits.

Trawling pressure 

Jenny Hickman, who completed this research as part of her MSc Marine Conservation program at the University of Plymouth, emphasized the lack of trawling pressure at the shipwreck sites.

“The industrial use of bottom towed fishing gear has been commonplace since the 1800s, and has significantly altered marine communities and ecosystem services. Outside of legal protection, only areas inaccessible to trawlers are offered any protection, which is why shipwreck sites are rarely subject to trawling pressure,” explained Hickman. 

“As many have been in situ for more than 100 years, they offer a baseline of ecological potential when trawling pressure is reduced or removed.”

Focus of the study

The research was conducted around five shipwreck sites off the Berwickshire coast, believed to have sunk in the late 19th and early 20th centuries. 

The team gathered video footage from these wrecks, the surrounding areas, and control locations, assessing the diversity and abundance of marine species.

Ecosystem recovery 

Joe Richards, Scotland Project Manager for Blue Marine Foundation and co-author of the study, expressed his excitement about the findings. 

“It has long been thought that shipwrecks could be playing an important role in providing sanctuary for marine species to utilize. It is brilliant to see this proven in this study,” said Richards.

“The research provides an insight into what might be possible if bottom towed fishing activity is reduced. This feeds into our wider understanding of shipwrecks potential to contribute to ecosystem recovery and enhancement, given the sheer number found on the seabed.”

Study implications 

The University of Plymouth and Blue Marine Foundation have a long-standing collaboration, studying the benefits of Marine Protected Areas (MPAs). Their research, including studies in the Lyme Bay MPA, has informed the UK Government’s approach to MPA management. 

The researchers say the latest study demonstrates the importance of factoring wreck sites into future conservation plans, but also the benefits of Marine Protected Areas (MPAs) status.

“In recent years, the UK has made significant strides in terms of measures to protect the marine environment. There is still much to be done to reach the goal of having 30% of the ocean protected by 2030, but if we are to get close to that we need detailed evidence about what makes our ocean so special and any existing initiatives that are working well,” said study senior author Dr. Emma Sheehan.

“This study builds on our existing work in that regard, and highlights an impact of past human activity that is actually having a positive impact on the seabed today. It is unquestionably something that should be factored into future marine management plans.”

Image Credit: marcusrose.gue

The study is published in the journal Marine Ecology.

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