Three hundred years ago the view from the cliffs of Cornwall would have been very different. Rather than today’s lonely fishing trawlers, the scene was dominated by the glistening bulk of blue whales. Huge schools of harbour porpoise chased shoals of fish so thick they darkened the water, while common dolphins filled the inland waters. Eighteen-foot orca menaced the mammals, while schools of blue sharks harassed fishermen who ventured out to dip their nets.
The vision may seem like the stuff of legend, but by delving into ship’s logs, ancient manuscripts, tax records, legal documents and even the devoted labours of monks living in Russia’s frozen north, an international team of researchers — part of the ten-year Census of Marine Life — has revealed the teeming abundance of life that once filled the seas not just off Britain but around the world.