biodiversity |

Earlier this month, Mowi Scotland sent me a press release and some underwater photographs taken around its salmon farm at Loch Hourn. The images were taken by a dive team from Tritonia Scientific, an independent marine survey consultancy, after Loch Hourn was the subject of a recent environmental pollution report. They show how a huge range of species is thriving, with the seabed and mooring lines teeming with life from feather stars, kelp and sponges to squirts, jellyfish, wrasse and anemones.

The press release also included some comments from Stephen MacIntyre, Head of Environment at Mowi Scotland.

“Protecting our marine environment is at the heart of everything we do,” he said. “That’s why we commissioned an independent environmental survey of the seabed and waters around our salmon farm at Loch Hourn.”

“There are a lot of misconceptions around the environmental effects of fish farming, with rush to judge and apportion cause and effect,” he continued.” In response, it’s important we acknowledge such concerns but that we also investigate, monitor and transparently present observational field data to inform more reasoned opinions. At Mowi, we are committed to responsible and sustainable operations that ensure we meet our environmental standards and thresholds. We take any concerns that we are not operating to those standards seriously. When claims were made that our farm was harming the loch, we investigated. The results are clear: salmon farming in Loch Hourn is not damaging the marine ecosystem. In fact, it’s coexisting with it.”

“The photos definitely speak for themselves. This is what responsible fish farming looks like in a well-managed environment,” MacIntyre concluded.

Fish farming is a huge food production sector that contributes to the global economy, food safety and more specifically to rural development in coastal areas where employment opportunities are often limited, e.g. islands. However, with the global push towards sustainable development and blue growth, understanding and addressing the environmental impacts of fish farming is crucial. We often hear about its negative impacts, such as water pollution from the release and accumulation of waste, the transmission of disease, escapes and the use of antibiotics and chemicals. However, when done wisely, fish farming can be part of the solution, slowing or stopping the negative impacts and helping to restore ecosystems. As Mowi Scotland’s photos show, Atlantic salmon and the wider ecosystem in Loch Hourn can flourish side by side. This is just one of many examples of how offshore fish farms can co-exist alongside, and significantly benefit, marine life.

In the Mediterranean, finfish, in particular bluefin tuna farming, is one of the most common types of aquaculture. There, one study confirms the benefits of fish farms to the surrounding marine environment. Researchers at the Institute of Oceanography and Fisheries in Split, Croatia, say that wild fish aggregations near caged farms can persist year-round due to abundant food supplies. Fish are also attracted by additional structures that provide protection and numerous favourable habitats for juveniles. According to the researchers, this impact of aquaculture on marine life can be considered positive as it enables adults to be in good condition for future spawning, while artificial nursery grounds can be provided for juveniles that inhabit areas within aquaculture installations. Considering the fact that each fish farm represents additional nutrient/energy input into the surrounding ecosystem, the role of wild marine biota aggregated around farming sites is also important in preventing local degradation of the environment.

The study concludes by saying that well-balanced, properly managed marine aquaculture operations should not significantly alter the surrounding environment. It adds that identifying potentially suitable areas for fish farming should take into account the ecological, technological, economic and socio-cultural impacts of different locations to avoid any environmental pressures.

Researchers at the University of Michigan agree that carefully managed farms make it possible to farm more food from the sea while reducing any negative impacts on biodiversity. In order to predict the impact of increased seafood production, the researchers built a model to determine the effect of offshore farms on over 20,000 species of marine fauna, and how this could change by 2050 depending on what was farmed and where. They found that building farms in the most eco-friendly areas led to promising results for both fish and shellfish. Bivalve production could increase by 2.36-fold and finfish production by 1.82-fold compared to current production, while global farming impacts would decrease by up to 30.5 percent under the best-case scenario. The researchers also point to the importance of strategic planning when installing farms and working with experts from various fields who can assess a wide range of considerations.

Shellfish aquaculture is also deemed as having positive effects on the marine environment. Not only is it able to improve water quality by assimilating nutrients from surrounding waters, but it also provides habitats to juvenile fish in areas where oyster reefs, algae ecosystems or seagrass beds have degraded. Compared to fish, shellfish typically do not require any chemical treatments such as high amounts of antibiotics. One of my favourite examples of shellfish farming improving ocean health and biodiversity is mussels. These can be grown on ropes suspended in the water, resulting in little to no habitat disruption. Because they feed naturally by filtering algae and other plankton, they also play a key role in improving the quality of the surrounding water. In addition, by creating biogenic reefs on the seafloor from clumps and shells, it’s possible to attract a range of species from demersal fish to macroalgae and mobile benthic invertebrates. Studies in New Zealand’s Hauraki Gulf also show that mussel farms not only support marine biodiversity but also increase wild fish populations. Research at the University of Auckland has revealed that marine species near mussel farms display greater diversity and abundance. Fish also appear to consume more nutritious diets near farm sites, suggesting that mussel farms can bolster biodiversity and fisheries productivity when implemented in the right locations.

These examples represent a paradigm shift in farming at sea, transforming it from a potential environmental threat into a tool for increased biodiversity and restoration. As aquaculture expands and we look to the future of sustainable, responsible seafood production, fish and shellfish farming stand out as promising solutions, acting as biodiversity hotspots, nurseries and places of refuge for a variety of species. With continued research and development, they have the potential to make a difference by playing key parts in the production of sustainable protein and contributing to marine conservation objectives. This, in turn, is likely to greatly boost social and economic benefits in certain areas. Hopefully, these efforts will continue and we reach a future where more fish and shellfish farms help restore and protect marine biodiversity while feeding the world.

Since its release in May 2025, Sir David Attenborough’s new documentary, Ocean, has been generating discussions on a host of issues related to the plight of our seas. After watching it myself, I can see why it’s provoked such a significant response. It’s a celebration of marine life and a stark reminder of the threats facing the ocean today.

The aims of Ocean are clear – to protect the seas and send a message of hope. The documentary does an impressive job of demonstrating how almost every marine ecosystem is capable of regenerating in months or years. The messaging on the ocean’s resilience, capability for abundance and capacity to bounce back is encouraging. Ocean is also beautifully shot, with incredible scenes of kelp forests, coral reefs and brutal images of bycatch. Like many of Attenborough’s documentaries, I really enjoyed this footage, which captures the beauty and rich diversity of the seas so well while describing the far-reaching effects of losing both and the importance of taking steps to move in the right direction. Attenborough also says that knowledge is important for change. Ocean offers viewers a lot of important information that gives them plenty to think about and discuss.

One issue that the documentary hones in on is the destruction caused by bottom trawling. Footage of the practice and its effects are shocking. There is also a focus on scallop dredging and bycatch-heavy hauls where the bycatch is simply discarded. It’s a dark visual representation of commercial fishing, and the message behind it is powerful. As discussions over the documentary continue, there will undoubtedly be significant impacts on consumer trust towards seafood and public perceptions of commercial fishing.

There is no doubt that this kind of destruction needs to be highlighted, and Ocean raises key questions about how certain fishing methods are carried out and where they occur. However, the portrayal of bottom trawling and scallop dredging could benefit from additional context, and it was a shame that no fishermen or fisheries scientists were featured. Ocean makes many important points about the need to protect the sea and its fish stocks, and the debate around marine protection is essential. However, there was no mention of the people who work on fishing vessels every day or an introduction to the latest research by fisheries scientists. There was also no mention of the many important advances in sustainable fisheries management and fishing practices that are happening today. Through my work, I have come across an array of efforts from seasonal closures, gear modifications, gear that is designed to reduce seabed contact or minimise bycatch, monitoring systems on board vessels, and the use of AI to ensure that the ocean and its inhabitants are free from dangerous items like ghost gear. These are all evidence of a strong commitment to try and improve sustainability and establish well-managed fisheries.

The UK public body Seafish says that in the UK, bottom trawling is managed as part of a broader fisheries management framework to ensure that impacts on fish stocks and marine ecosystems are avoided, mitigated or remedied. Seafish offers information on temporary, seasonal or permanent closures of fishing areas if there are concerns over marine conservation, and highlights the role of trawl fisheries in supporting coastal communities and fishing on grounds that have been fished for generations. Earlier this month, the UK also outlined plans to ban bottom trawling in more Marine Protected Areas (MPAs) to protect habitats and support important marine species such as lobster, clams and langoustine. Meanwhile, The International Council for the Exploration of the Sea (ICES) also monitors bottom trawling worldwide and publishes independent assessments of the impact on seabed habitats.

The UK is also aware of the issues surrounding scallop dredging and is working towards better management in this fishery. Two years ago, consultations were held on a king scallop fisheries management plan in England and Wales. Stakeholders discussed the introduction of dredge restrictions to protect scallop stocks, reduce any impact on the seabed and other marine species, and ensure the scallop industry’s future economic security. There was also a desire for king scallop stocks to be better understood, to identify interactions with the wider marine environment.

Professor Ray Hilborn, a marine biologist and fisheries scientist at the University of Washington, shared his opinion on Ocean in his latest newsletter, which I read after viewing the documentary. He pointed out that although unregulated fishing is a threat to marine ecosystems, so too are climate change, pollutants, plastics and terrestrial runoff of nutrients. He also explained that bottom trawling occurs only in a small portion of the global ocean, almost exclusively confined to continental shelves, and in countries with the largest amount of continental shelf — Russia, Canada, the USA, Australia and the Antarctic – the proportion of area trawled is very small. Most bottom trawling also occurs over more resilient environments such as sand, mud and gravel, he said, rather than more sensitive areas such as deep-sea coral or sponge beds. In fact, research shows that benthic communities in more resilient environments recover quickly, especially when trawling is well-managed.

Hilborn concluded by stating that fishing of all forms, including trawling, can be done sustainably, ensuring food production for future generations.

The UK and US are just two tiny examples of awareness towards the negative impacts of bottom trawling and scallop dredging. There are many more examples and viewpoints, and other nations are pursuing their own measures and working towards global agreements on marine conservation. This is more important than ever in light of this year’s UN Ocean Conference.

It’s worth highlighting that Ocean doesn’t say that commercial fishing as a whole is bad. The documentary is beautiful but devastating, and a reminder to all of us in the seafood sector, whether it’s fisheries or aquaculture, to think further about how we can take even more effective steps than the ones we are taking now. It’s exciting to see, once again, the attention given to critical issues that the ocean is facing. But at the same time, it’s important to remember that scientists, the fishing industry and more have been working hard for many years to improve fisheries and build something more sustainable. Like Seaspiracy, Ocean is a great opportunity for healthy, open discussions on fisheries, regulation and environmental protection, where all stakeholders can come together in a collaborative way.

Tag Archives: biodiversity

How ocean farming can coexist with marine biodiversity

Looking Back on Ocean