It aims to encourage more people to give fish a miss at the end of the week to highlight the unsustainable nature of the fishing industry.
It also suggests that meat-reducers may unwittingly be contributing to the problem, by eating more fish to supplement their decreasingly carnivorous diets.
“Ordinary people are starting to realise that cutting down on meat will improve their health and reduce their environmental impact, but many turn to fish as a ‘solution’,” says the Vegetarian Society website.
Industrial fishing techniques are responsible for a number of negative impacts, according to the UN Food and Agriculture Organization’s fisheries and aquaculture department.
These include overfishing, which leads to changes in biodiversity and species composition, bycatch or fish discarding – the focus of chef Hugh Fearnley-Whittingstall’s recent Fish Fight campaign – and ghost fishing, where lost or abandoned equipment continues to catch and kill fish.