High Seas Drifters

Gangs of workers dressed head to toe in hazard suits pick their way along the rocky banks of the Laerdalselva river in Norway. Pesticide dispensers in hand, they release showers of toxic rotenone. In eddies and shallows further downstream, scores of hook-jawed salmon – fish that were once vital and bristling with silver vigour – gasp forlornly at the water’s surface, gulping down air as they shiver out lingering deaths.

The Laerdalselva is just one of at least 41 Norwegian rivers that have been colonised by the parasite gyrodactylus salaris over the last 25 years. The parasite was transported into these rivers by millions of farmed salmon that breached their cages and fled upstream to reproduce. Latching onto wild fish and causing them infection-prone bleeding wounds and sores, the tiny organism rapidly decimates the native salmon in any stream it invades. The cure? Annihilate every living thing in the river.

Far away from Norway’s arctic torrents, in the tropical waters off Hawaii, other species of fish are being farmed. But off Ewa Beach, Oahu, the site of the submerged fish cages of Cates International, the scene is very different: it all seems tranquil and benign.

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