Beyond kelp Is seaweed our next great hope?

‘You can just see the buoys of the seafarm,” Dr Sophie Steinhagen yells over the high whine of the boat as it approaches the small islands of Sweden’s Koster archipelago. The engine drops to a sputter, and Steinhagen heaves up a rope to reveal the harvest hanging beneath: strand after strand of sea lettuce, translucent and emerald green.

“This is one individual that we would collect now and keep as a parent, because it’s growing very fast,” she exclaims. In summer, these waters teem with sea kayaks and yachts from neighbouring Norway, but for Steinhagen and the seafarming group at the Tjärnö Marine Laboratory, spring is their peak season.

For one thing, it means less animal and plant life on the seaweed. “When you buy a lettuce, you don’t want to have a caterpillar in there.