What are the fish species that require the most and least amount of fuel to catch?

Your ethical dilemmas sorted

With fishermen across Europe protesting about rising fuel costs, what are the fish species that require the most and least amount of fuel to catch?
T Cryer, Dorset

Many of us have now got into the habit of looking for the Marine Stewardship Council's logo that signifies that the fish we are eyeing up in the shop comes from a sustainable source. For example, rope-grown mussels and line-caught Cornish mackerel are in, but swordfish and snapper are out. Conveniently, there is also something of a direct correlation between sustainable fish and lower-than-average volumes of fuel used by fishermen to land them. It makes sense when you think about it: the harder and further a fleet has to hunt for any given species, the more likely it is to be one that comes from an exhausted or even endangered stock.

But it is the many methods of fishing, rather than specific species of fish, that lead to the often huge variations in fuel use. The Sea Fish Industry Authority, "the UK's only cross-industry seafood body", says that the most fuel-intensive fishing methods are beam trawling (which typically lands flatfish such as plaice, sole and megrim), mechanical dredging (scallops and clams), demersal trawling (whitefish such as cod, haddock and monkfish), nephrops trawling (langoustine, Norway lobster and prawns) and creel and pots (lobster, crabs and conger eel). The most efficient methods use line and hooks to catch species such as mackerel, hake, and sea bass.

Dr Peter Tyedmers, an ecological economist based at Dalhousie University in Nova Scotia and a leading expert on fuel use by fishing fleets, says that herring caught using purse seine nets (which catch schools of fish that gather close to the surface) can use as little as 20 litres of fuel per tonne of live fish landed, whereas trawling for prawns can use up to 2,000 litres of fuel per tonne of live fish landed. Canadian fishermen today, he says, now use four times as much fuel per tonne of fish as they did in the 1930s due to reduced stocks. Fish farms don't automatically equate to lower fuel use either, because of what he calls "feed miles" - the energy needed to produce fish food, much of which is, due to the carnivores that we tend to farm, wild-caught species that are processed into feed.