We like eating fish so we want fish to eat. Sadly, our great oceans don't have an endless supply so we can't all eat all of the fish all of the time. Therefore, we need to ask "which fish can we eat now?"
There is no simple answer to this question. A strict diet of sardines won't save the seas. Fish stocks, by nature, are ever-changing, so scientists need to monitor them carefully to estimate population changes. This helps to make decisions on which fish are considered 'good to eat'. There are resources you can use to keep up to date (the Marine Conservation Society's FishOnline is very good), but most people will naturally rely on information in front of them, on packets, tins and menus, to make a sustainable choice.
Labels are crucial. Millions of purchasing decisions rest on small pieces of seemingly vague information. Lots of labels say things like "sustainably fished" or "responsibly sourced" and why shouldn't people accept those statements? If it's good enough for a top supermarket, it must mean something, we might think. There are laws to enforce this sort of thing, aren't there?
Unfortunately, from shop to shop and product to product, choosing a "sustainable" option based on label alone is something of a lottery. That's not to say that all stores and restaurants are simply writing "sustainably fished" with no justification. Some brands already have very good labelling and sourcing policies, but what "sustainably sourced" means can vary enormously.
The good news is that if you live in the UK, the meanings of these terms are about to become clearer. In one year, you will be able to walk into a supermarket, look at environmental claims and have confidence that they are meaningful and mean the same thing from store to store.
In January 2011, environmental lawyers at my organisation ClientEarthcriticised seafood brands for making misleading environmental claims on products like tinned tuna, haddock, cod and farmed fish. Tesco was confronted by Hugh Fearnley-Whittingstall with a copy of this report on the hugely successful Fish Fight programme.
The reaction to this report was refreshingly positive. Seafood brands acknowledged the problem and wanted a platform to help solve it.
As a result, the Sustainable Seafood Coalition (SSC) was born. It is the first cross-industry group in the UK to tackle seafood sustainability using the influence of seafood businesses. Members include River Cottage, Birds Eye UK, Tesco, Morrisons, Sainsbury's, Waitrose, Marks & Spencer, Co-operative Food and other brands.
On Thursday, at the Humber Seafood Summit, the Coalition launched two voluntary codes of conduct. The codes cover environmental claims on their own brand seafood and the sourcing policies they use when choosing which fish to sell.
This means change is coming to a shop near you. By 18 September 2015, all voluntary environmental claims like 'sustainably sourced' and 'responsibly sourced' on members' own-brand seafood will be consistent, clear and accurate.
The good news goes deeper than labels. For the first time, the codes commit members to making the source of their own brand seafood fully traceable. It ensures all members commit to sourcing their seafood in line with the codes regardless of whether or not they make any voluntary claims on a label.
Therefore, if people buy own-brand seafood in a member's store, they will be able to find the origin of the seafood, check it against the publically available code and ask the SSC member why they consider it "responsibly sourced".
In 18 months, my colleagues at ClientEarth will publish an update of our report on environmental labelling investigating whether or not members have implemented the codes adequately or not.
When we launched the Sustainable Seafood Coalition three years ago, some thought getting so many brands to agree like this was impossible. Today's milestone shows it can be done. Now we've shown it is possible in the UK, we hope this example will be followed around the world.
Which fish can we eat now? The question isn't about to go away, but it's about to get easier to answer in restaurants and shops. This is just a start, but together we can all do our bit to help our oceans return to being thriving, healthy ecosystems with plentiful, and delicious, seafood for all. Always check the label.