UK pork production is up: new government figures for last year show a 4% increase on production in 2020, to just over a million tonnes. Regular listeners who have heard pig farmers on this programme talk about how shortages of staff in abattoirs have forced them to kill pigs on farm, pigs which then can’t go into the food chain, may wonder how an industry in crisis can have a record year - it's the highest production level since 1999. We ask how a how a year of backlogs on farms fits with record production levels. All this week we're looking at pollution from farming, both causes and solutions. Today we hear from Professor Penny Johnes from Bristol University who studies the impact of food production on rivers and the sea. Presented by Charlotte Smith and produced by Beatrice Fenton.