Exclusive: pork industry’s role in pollution of one of Europe’s largest saltwater lagoons may be greater than publicly acknowledged, investigation reveals

Pollution from hundreds of intensive pig farms may have played a bigger role than publicly acknowledged in the collapse of one of Europe’s largest saltwater lagoons, according to a new investigation.

Residents in Spain’s south-eastern region of Murcia sounded the alarm in August after scores of dead fish began washing up on the shores of the Mar Menor lagoon. Within days, the toll had climbed to more than five tonnes of rotting carcasses littering beaches that were once a top tourist draw.

Images of the lagoon’s cloudy waters and complaints over its foul stench dominated media coverage across Spain for days, as scientists blamed decades of nitrate-laden runoffs for triggering vast blooms of algae that had depleted the water of oxygen – essentially leaving the fish suffocating underwater.

A four-month investigation by Lighthouse Reports and reporters from elDiario.es and La Marea examined how intensive pork farming may have contributed to one of Spain’s worst environmental disasters of recent years.

This summer, as lifeless fish continued to wash up on the shores of Mar Menor, the regional government banned the use of fertilisers within 1.5km (0.9 miles) of the lagoon, hinting that blame for the crisis lay solely with the wide expanse of agricultural fields that border the lagoon. The central government was more direct, accusing local officials of lax oversight when it came to irrigation in the fields.