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Shrimp may be small, but they are big business. The global trade in shrimp and prawns was estimated in 2020 to be worth around $28bn a year or almost a fifth of the world's total fish trade in value. More than half of the world's shrimp is farmed. Though this began on a large scale only in the 1970s, it has grown fast. Production rose five-fold between 2000 and 2017. Despite labour shortages due to the pandemic, final figures for 2021 could put global output up another 10 per cent from 2020.
Seafood farmers argue that marine protein is better for the planet when compared with livestock farming. More farmed production means less depletion of wild shrimp stocks and less impact from trawling. But farmed shrimp comes with its own environmental cost. Shrimp farms are positioned in tidal areas to minimise the cost of pumping water and they often use chemicals and antibiotics that pollute the surrounding areas.
These intertidal zones are also the perfect habitat for mangrove forests. Uniquely adapted to survive in saltwater, mangroves sequester up to four times more carbon than rainforests. According to the non-governmental organisation Global Mangrove Watch, about 35 per cent of the world's mangrove forests disappeared during the 1980s and 1990s. Clearance for shrimp farming was a major cause. Because of mangroves' capacity to absorb carbon dioxide this has had a significant effect on greenhouse gas emissions. A 2017 study conducted by forestry researchers, CIFOR, calculated that the clearing of mangroves meant that 1kg of farmed shrimp had almost four times the emissions impact of a kilo of beef.
Mangrove deforestation has gradually slowed and the industry itself is slowly evolving. Since 2014 for example, the sustainable aquaculture consultancy Blueyou has marketed its Selva Shrimp brand on its environmental impact, raising shrimp in a responsibly managed way. Sustainability certification has proved a logical way to encourage best practise. Only 10 per cent of shrimp and prawn production was certified in 2020. That was better than for many aquaculture species but a lot less than for salmon at just over 40 per cent. If shrimp is to help feed the world sustainably consumers may need to check the labels and vote with their wallets.