Results from a long-term study of fish communities in the Bay of Somme in the English Channel show that numbers of cold-water fish, such as dab and plaice, have been dropping since 1998, as sea temperatures have risen. The researchers say this is evidence of ‘tropicalisation’ in an English-Channel ecosystem. The findings may have implications for conservation policies in the Bay, which is a Marine Protected Area1 designated under the Natura 2000 programme, as well as other marine sites affected by warming.