Shoppers in the UK have long been told to swap cod for hake or coley. Now those fish are in trouble too, a UK ocean charity said on Wednesday.

The Marine Conservation Society publishes the Good Fish Guide, which rates seafood with a traffic-light system. On Wednesday it lowered its rating for European hake caught in the North Sea, the Celtic Seas and the Bay of Biscay from green to amber, the Guardian reported. The charity said stocks are falling and fishing pressure has grown.

Coley caught around the UK, including in the North Sea and off western Scotland, dropped to red, the guide's worst rating, the Independent reported. That makes it a "fish to avoid," the Guardian said. The charity said coley numbers are falling and there is no recovery plan in place. Haddock caught off Iceland also slipped from green to amber, the Independent reported.

Not every fish was downgraded, however. Cornish hake and coley from Icelandic waters kept their green ratings, the Independent reported. Haddock from the North Sea and Scottish waters also stayed green. Some North Sea herring was upgraded, and Atlantic bluefin tuna in UK waters got a new green rating.

Kerry Lyne, who runs the guide, said a "fish that was a good choice a few years ago is not necessarily a good choice everywhere today," the Guardian reported. "The best thing we can all do if we eat seafood is diversify our seafood choices and avoid those most under threat," she said, the Guardian reported.

Most seafood eaten in the UK comes from just five species, the Guardian noted: cod, haddock, salmon, tuna and prawns. That puts heavy pressure on a small number of wild fish populations. For white fish, the guide suggests Alaska pollock, monkfish from the North Sea or most seabass, the Independent reported.

What we know: The charity downgraded some hake to amber and UK coley to red on Wednesday.
What we don't: Whether shops and restaurants will change what they sell.