Eat fewer prawns (and scrimp on the shrimp)
Last updated Wednesday 30 April 2008
Seek out more sustainable seafood
By the time a prawn makes it to your sarnie, there's a good chance it's been on a cruise to the Far East to be hand-peeled, deep frozen for a month and shipped back. And the trawler that caught it coughs up more than 20 times as much greenhouse gas in just over a week than a small diesel car does in a whole year.
Farmed prawns put paid to the trawling but destroy valuable CO2-soaking-up mangroves. Small, cold-water prawns may be a less-bad option than tropical 'tigers', but neither variety is a clear choice for the carbon-conscious.
That said, some near-shore seafoods (like clam, crab and lobster) can be harvested without trawlers, requiring relatively little energy. Could it be time to broaden your palate?
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How will it make a difference?
Pub Fact
- For every kilo of shrimp caught, 40kg of other marine animals are discarded on average
- The total area of the world covered by mangroves was 15 million hectares in 2005, reduced from 19 million hectares in 1980
- The EU is the world's biggest importer of prawns
- Approximately 5 million metric tons of shrimp are produced annually
- Shrimp fishing in the North Sea can require about 1.5kg of fuel per kilo of shrimp caught
Prawn fishing is not just energy-intense. It is the most energy-intensive fishing industry on Earth, according to Swedish research. Producing a kilogram of trawled, de-shelled prawns uses about ten times more energy than producing the same weight of clams. In fact, prawn trawling uses almost 20 times more fuel per tonne of catch than the small-fish industry according to research by Dalhousie University in Canada.
All in all, global fisheries use over 1% of global oil consumption - as much as the entire national consumption of the Netherlands.
Trawling accounts for the lion's share (about 70%) of a wild prawn's footprint. In fact, a typical diesel-powered shrimp trawler on a ten-day trip emits about 37 tonnes of CO2. That's about eight times as much CO2 as the average Brit produces in a year.
Bottom trawling for seafood is fuel-intensive because it involves dragging nets that are a kilometre long and as tall as eight double-decker buses along the ocean floor, with up to 15 tonnes of weights attached. This can destroy valuable sea-bed ecosystems and the carbon-storing phytoplankton that sometimes depend on them.
Sadly, prawn farming - the main alternative to wild prawns - is hardly sustainable either. Yet farmed shrimp is one of the fastest growing forms of aquaculture, now accounting for one-third of the shrimps produced globally. Built on tropical coastline, shrimp farms require the clearance of mangroves - coastal swamps that soak up CO2 from the atmosphere and so protect against climate change. In fact, new shrimp farms have been linked to almost half of all global mangrove loss to date. Plus, shrimp are carnivorous, and farming them intensively requires protein feeds (often wild fish) of more than double the weight of the prawn produced.
Fewer mangroves also mean fewer fish because 85% of all commercially-fished species depend on mangroves as nurseries in the tropics, according to the United Nations Environment Programme.
For the average Brit - who eats just two bags of frozen, trawled prawns a year - giving up prawns altogether would save about a third as much CO2 as putting a water saving device in your toilet - or as much CO2 as is released by the production of a CD. Of course, if prawns are a regular feature on your dinner table then the potential carbon savings from cutting down are much larger.
What's the debate?
"I only buy 'sustainable' prawns. Surely that means they're climate-friendly?"
Nope. While 'sustainable' seafood is certified to be environmentally-friendly, it isn't necessarily doing the climate any favours. This is because the Marine Stewardship Council only takes into account environmental impact and stock-sizes - not CO2 emissions - when deciding a seafood's sustainability. For example, the Oregon Pink Shrimp is certified as sustainable despite the fact that the carbon footprint of its harvesting method has yet to be assessed, according to the Shellfish Association of Great Britain.
"Is eating prawns that are shelled by machine in the UK better for the climate than eating prawns that are shipped to South-East Asia to be hand-shelled?"
While food miles (the distance food has to travel to get to your plate) generate emissions, how the food is produced tends to be far more important. In fact, the Carbon Trust found that prawns shipped to South-East Asia to be hand-shelled are no worse for the climate than prawns shelled in the UK, because of the energy-intensity of shelling machinery in Britain. Read more about it in this Times article.
"If we don't buy tropical prawns, then won't local communities' livelihoods suffer?"
Although the shrimp industry is lucrative for some, the pollution, disturbance, and social conflict created by trawlers can reduce local fish stocks and destroy the livelihoods of subsistence fishermen, threatening food security in some of the world's poorest countries.
What's stopping me?
"But I love prawns"
If you simply can't go prawn cold-turkey then seek out British trap-caught varieties. They're fairly difficult to find, so the next best thing for the environment is the sustainable, cold-water prawn. Best of all, try to swap prawns for other low-energy seafoods. (Check below for tasty low-carbon alternatives.)
How do I do it?
- Choose low-carbon seafoods that have low-energy fishing methods. Look for line-caught, trap-caught and hand-gathered seafoods like pot-caught prawn, creel-caught Dublin Bay prawn, mussel, lobster, crab, clam, Burry Inlet cockles, beach-caught North Yorkshire sea bass and herring
- If you can't avoid prawns, look for cold-water, sustainably-managed prawns from Norway, Iceland, Denmark, Greenland and Canada. Cold-water prawns are small and white, whereas tropical 'tigers' are large and brown
- Avoid scallops, which require energy-intense dredging. Also try to avoid other energy-intensive fishing industries, such as tuna and swordfish - which frequently consume in excess of 2000 litres of fuel per tonne of landings
- Check on the Marine Conservation Society's website for supermarkets that are likely to stock 'sustainable' prawns: Fish Online
- Read the Environmental Justice Foundation's guide to prawn purchases
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I used to work on a trawler, many years ago, for scallops in the Indian ocean. The scallop trawlers worked in much the same areas and with much the same method as the prawn trawlers and they wreaked absolute devastation on the seabed. We were trawling up sea snakes, turtles, seahorses (which die very quickly out of water), sea sponges, really the entire marine ecosystem and I later discovered that the boat I worked on had trawled up a dolphin - but threw it back in dead because they didn't want to report it. The blokes who worked on the boat were bored and would shoot seabirds and break the noses of the shovelnose sharks before throwing them back in, to watch them frantically trying to swim down and being unable to - needless to say, I didn't work on the boat very long!
As for farmed shrimps, the destruction of the mangrove swamps, as described in the article above, was responsible for making the effects of the 2004 Boxing Day tsunami worse, because the coastal areas had less protection. What's more, coastal communities have been prevented from moving back to the areas they used to live in by commercial shrimp farming industries. So this one is very much a human rights issue as well as an environmental one.
Happy crab eating everyone!
© MMIX
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