Some large contract caterers serving food in UK event venues have admitted including on their menus species of fish on the red at-risk list compiled by the Marine Conservation Society (MCS). Species are red-listed because of over-fishing endangering their survival, because they are produced unsustainably, or because some part of the supply chain involves slavery.

Caterers admitting to serving red-listed fish are Compass Group UK and Ireland, ISS and Sodexo, and the survey was carried out by food charity Sustain.

The MCS recommend that caterers avoid 63 varieties, including yellow fin tuna, king prawns and eel.