Getting people excited about fish isn't exactly easy. But somehow Hugh Fearnley-Whittingstall and Channel 4 have managed to do it, bringing a new level of public scrutiny to the plight of fish stocks. Hugh's Fish Fight campaign already has more than 600,000 signatures, and now has big retailers promising to change their labelling and sourcing policies. They deserve congratulations and support.

There is, however, a lingering concern about their proposed solutions. Simply encouraging British people to be more adventurous and try new species such as gurnard, coley or dab will not automatically ease pressure on stocks most at risk. On the contrary, it could result in an increase of total amount of fish eaten. It may be happening already: last week, Marks & Spencer and Waitrose reported increases in fish sales of 25% and 15%.

People in Britain each consume about 20kg of fish per year. That's only half of what a Spaniard eats, and three times less than a Portuguese, but it's still much more than what the average world citizen eats. In the context of declining global fish stocks and rising global demand – as reported by the UN's Food and Agriculture Organisation (FAO) – increasing the total amount of fish eaten in the UK is unlikely to solve overfishing.

The UK eats more than its stocks are able to produce: it imports more than twice the amount of fish product it exports, and depends on fish from other countries for more than five months in the year. This dependence on fish from abroad makes the industry more vulnerable and reduces food security in countries that need the fish more than us.

But this trend is increasing. If the UK had to rely on its own fish supply to satisfy current demand, it would run out by mid July: three weeks earlier than last year. Quite bad for a nation surrounded by potentially rich and productive seas, but still better than Spain, France and Germany, which are fish dependent for more than half a year.

The main reason for this fish deficit is that three-quarters of EU fish stocks – including British ones – are overexploited and produce much less than they used to, or what is possible. Stocks, when properly managed, are a long-term source of prosperity and jobs: unsustainabe management is economically, and ecologically, careless.

A recent study by the Centre for the Economics and Management of Aquatic Resources (CEMARE) shows that UK catches for cod, whiting and haddock could be five, four and three times bigger if stocks were allowed to recover, with the potential to increase economic gains ten-fold to more than £500m. How this is done and who would benefit most from this is a matter for another discussion, but the figures give an idea of why fish stock restoration deserves at least as much – if not more – attention as the promotion of new fish species into British fish eating habits.

Creating a market for under-utilised species, which would otherwise be discarded, could help to stop edible fish being thrown overboard. But, as the OCEAN2012 coalition suggests, the priority should be to ensure that unwanted catches are avoided, and that any ban on discards is based on the principle of avoiding unnecessary wastage, rather than creating new markets that use discards of unwanted or unsustainable catches such as immature fish or endangered species.

The upcoming reform of the Common Fisheries Policy (CFP) is a perfect opportunity end to discards and restore stocks to healthy and sustainable levels. Getting this piece of policy right will be critical to guarantee that in the not-too-distant future European consumers can go to the supermarket and buy fish with peace of mind, knowing that it all comes from sustainably managed stocks.

In the meantime, responsible consumers can reduce the amount of fish they eat – by far the safest option when it comes to satisfy concerns about the sustainability of stocks. They can also buy products certified by the marine stewardship council (MSC); it's far from perfect but it's the most widely recognised standard. Buying fish caught with static gear, such as gillnets, pots, bottom longlines, also helps, as will eating species that are at low levels of the food chain, including mussel, squid, crab, Norwegian lobster, sardines or sprat, which tend to be more abundant and reproduce more rapidly, so eating them has less impact on the marine environment.

Simply bringing new fish species on to the menu without getting core fish stocks back into shape will only take the UK a step closer to becoming a fish-predator nation, such as Spain, Portugal or Japan, which all eat a much wider variety of fish but are far from providing models of sustainable fisheries management.

• Aniol Esteban is head of environmental economics at the New Economics Foundation