Q My husband says prawns are generally sustainable. Is he right?

A I wish he were. If the ubiquity of prawns (or shrimp) on menus was a symbol of robust global populations and a sustainable approach to their fishing, it would be reason to celebrate. Perhaps with a seafood curry.

In fact, it’s a bad omen, hinting at the destructive nature of industrialised shrimp farming. To feed our desire for a cheap source of this once luxury food, thousands of hectares of mangrove forest are being destroyed in Brazil and Bangladesh to set up shrimp farms, according to the Environmental Justice Foundation (EJF).

It’s no good choosing unfarmed prawns. The majority of these are trawled; a process that kills an estimated 150,000 turtles annually. The EJF says: “For every 1kg of shrimp that is kept, 40kg of other marine animals are discarded... at a time when over 70 per cent of the world’s fisheries are overexploited or in decline.”

So, what can you put in your prawn cocktail? Coldwater shrimp from Arctic oceans around Norway, Iceland, Denmark and Canada, which are sustainably managed. To find them, you’ll have to dig around a bit, put a few questions to your fishmonger, or pay close attention to supermarket labels.

It’s harder than finding sustainably caught fish because there is no ethical certification scheme. If you rely on the Marine Stewardship Council (MSC) eco flag to make your seafood selection, you’ll be stumped; the MSC has yet to certify any sources of shrimp.

For more tips on what to look for, download this pamphlet, published by the EJF (ejfoundation.org/pdf/ ejf_prawn_consumer_guide. pdf ). It suggests that consumers keep an eye out for the small but growing number of ethical producers that farm shrimp responsibly. You’re most likely to find them in Waitrose and Marks & Spencer, which came top of last year’s MSC league tables (see fishonline.org/ buying_eating).

Yes, there’s a premium, but perhaps it’s time to revive a Seventies approach to crustaceans, when a prawn cocktail was considered the height of luxury.

Q Do you know any companies that rent green vans?

A Tricky, this one. Unlike car manufacturers, van manufacturers are not required to publish CO2 figures for their models so it’s not easy comparing them and working out which ones are green. One company that has extracted some of this emission information from the motoring industry and used it to operate an eco-friendly car and van hire company is Green Motion (greenmotion.co.uk).

Mercedes and Volkswagen have declined to give CO2 emissions for their vans, says Richard Lowden, the managing director of Green Motion, but Ford, Renault and Citroën have been transparent. From these figures Lowden found that two Citroën models, the Citroën C2 Enterprise (113g/km CO2 ) and Citroën ), came out top. Green Motion set up shop four months ago and so far there are only three bases, in Oxford, Palmers Green, in North London, and Milton Keynes. There are grand plans to spread to 11 more locations this year.

Go Green, based in Cheshire, is another car and van rental company to take its environmental commitment seriously (gogreencarandvanrental.co.uk).

While there is nothing particularly pea-green about its vans, it invests 1 per cent of its annual profits in environmental education projects in the local area, a means of offsetting its emissions.

Despite advances in biodiesel technology, progress has been slow to turn vans green, with most still guzzling unwholesome quantities of diesel. There are simply not sufficient provisions to include biofuel vans in a rental business, according to Lowden. “It’s an empty gesture; there are only 14 filling stations that sell biodiesel in the UK.”

This makes the story of the two men from Dorset who returned earlier this month from a 2,600-mile trip to Timbuktu, in a lorry that ran on waste chocolate, all the more commendable.

Sadly, it will be some time before you see choc-powered vans at your local Hertz branch.

ECO BLOGWATCH

It is often said that homeworkers lead environmentally superior lives – no transport emissions in the journey to work, no plastic cups or sandwich wrappers in the bin. But during winter, there are other costs.

Heating the whole house is one, says Brian. “A cold body makes my back tense, which leads to trouble.” Hedgewizard generates his own heat. “My office needs no heat once I’ve been in there for a while,” he says. “But I’ll confess to using a fan heater to take the chill off first thing.” John Gregory Flinn claims that a wood-burner is the greenest way to keep warm if you work at home.

Homeworkers can also feel better about electricity by swapping to a green energy provider, such as Ecotricity (ecotricity.co.uk ) or Good Energy (good-energy.co.uk). Not that this gives you an excuse to leave your computer on lunchtime standby. “I keep my printers and fax unplugged until I use them,” says Siel. As for what to eat without a canteen, it’s a perfect time to polish off leftovers.

For green news and views, and Anna’s eco-blog at timesonline.co.uk/environment

GREENIE POINTS

DO IT

The perfect Valentine’s gift for a green lover? Fairtrade chocolate and organic knickers. This winning package is being offered by underwear company Green Knickers (greenknickers.org). Order a gift box containing a pair of pants – or boxers for men – and the chocolate comes free.

CLICK IT

As the first green shoots appear, before you start planning changes in your garden, find out which plant species are local to your area by typing your postcode into the Natural History Museum's search engine, nhm.ac.uk/fff. Local species will need less maintenance and they will also attract local wildlife.

SKIP IT

OK, the packaging is recycled and the content is from a naturally replenished source, but does your drinking water have to come from a spring in southwest Iceland? The green credentials of mineral water newcomer Icelandic Glacial (icelandicglacial.com) pale in comparison with the alternative, a glass of tap water.

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