It’s nutritionally good for us and a dietary staple around the world, but some seafood can have a significant impact on the environment.
Many of us are keen to improve our sustainability credentials, but does that mean forgoing the catch of the day entirely? We’ve been trying to find out – starting with prawns.
We look into the issues behind wild and farmed prawns, set out the labels to look for and explore the more sustainable options.
For more on seafood, including recommended swaps you can make at the fish counter, visit our guide to how to buy sustainable fish.
Wild prawns and the environment
Big warm-water prawns, often called tiger or jumbo prawns, usually come from south-east Asia. Those that are wild-caught are generally harvested by trawling the sea bed, often using an otter trawl, which is a cone-shaped net with rigid boards at the mouth that’s dragged along by a slow-moving boat.
Because the prawns are relatively small, the net’s mesh has very small holes. That means this fishing method comes with very high levels of bycatch – unwanted fish and marine creatures that get caught up in the net.
A report by the Sustainable Fisheries Partnership in 2015 found that harvests of warm-water shrimp fisheries comprised 75% or more bycatch, and the majority of the fisheries had annual bycatch volumes of more than 100,000 metric tons. This can include large numbers of turtles.
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What about farmed prawns?
Farmed prawns found in UK supermarkets are commonly from Thailand and Vietnam. Historically, these shrimp farms been associated with the destruction of mangrove forests.
Mangroves provide homes to a multitude of rare and threatened land and sea animals. They also naturally filter water and protect shores from erosion.
Studies have indicated that mangrove forests can store four times as much carbon as tropical forests in their soil and roots. Yet a fifth of them have been lost since 1980.
Shrimp farms are also associated with issues that apply to lots of intensively farmed seafood. The waste creates pollution, and the use of pesticides and medications can damage other wildlife.
Additionally, as a carnivorous species, prawns require animal protein to stay healthy. Some of this comes from wild fish caught specifically to feed farmed fish, which puts pressure on wild fish stocks.
On top of that, shrimp farms have been associated with signficant human rights abuses. Undercover investigations in recent years by the Environmental Justice Foundation and Associated Press have found evidence of trafficked and enslaved shrimp peelers in Thailand. Slave labour was also uncovered at sea, on the boats catching wild fish to feed the shrimp.
Is there a more sustainable option?
If you’re set on continuing to eat warm-water prawns, your best choice is organic (to mitigate against some of the environmental impacts) or prawns carrying the Aquaculture Stewardship Logo (ASC). Part of the ASC standards include farms demonstrating they’re treating workers fairly.
Another interesting option to keep your eye on is the Lincolnshire-based Flo Gro Fresh – currently the only UK-based prawn farm.
It’s currently closed while it expands its operations, but if you’re after sustainable warm-water prawns, it’s as good as you can get, according to the Marine Conservation Society, which rates the prawns as ‘green’ on its Good Fish Guide traffic-light-based app.
Its closed-loop system is powered by renewable energy, and the prawns’ feed is made up of waste trimmings from fish for human consumption.
Other seafood alternatives
While you might be able to find some more sustainable warm-water prawns, in general you’re better off looking for alternatives.
Cold-water, wild-caught prawns, typically from the waters between Canada and Norway, are often a better choice.
While they’re also harvested by bottom trawling, it’s often in areas of muddy sediment, where the lasting environmental impact is lessened and by-catch is less of an issue.
Choose ones that carry the Marine Stewardship Council (MSC) blue tick on their packaging.
If you’re a bit more adventurous and would like a really sustainable and nutritious option for your seafood linguine, you could swap your prawns for rope-grown, UK-farmed mussels.
These clever molluscs actively clean sea water, store carbon in their shells, don’t require feeding and are quite happy living on vertical ropes, which means harvesting them has no impact on the sea environment.
They are also impressive nutritionally – high in protein, omega-3 and iron, and containing an array of important vitamins and minerals.
Video: What fish is sustainable?
For more on our seafood investigation, head to our guide on how to buy sustainable fish.