Fishing is a huge business of irreplaceable economic and social value. Bottom trawling and shellfish dredging cover 75% of the world’s seas. Every year trawlers sweep an estimated area of seabed equivalent in size to half the world’s continental shelves.
Fishing boats dragging heavy ground gear plough seabeds and physically flatten habitats, remove seagrass, corals and other invertebrates and expose buried fauna. Bottom fishing is notorious as amongst the most destructive form of impact on seabed communities. Marine conservationists dub these trawlers ‘bulldozers of the deep’ and have sought ways of reducing their collateral impacts since 1960.
Sunken cultural heritage is at even greater risk than marine habitats, but as a threat enjoys no proactive management. Damaged fauna and flora can regenerate, whether seasonally or over decades. Once a shipwreck has been struck by fishing gear, the damage and erosion of knowledge is permanent. Arguably no historic sea lanes once traversed by ancient and historical merchantmen and warships remain untouched.
In the space of a few generations some seas have witnessed the pandemic wiping of their archaeological hard drives. Whereas other forms of impacts – oil and gas pipelines, aggregate dredging and wind farms – follow pre-determined lines, which can be surveyed and mitigated when they run close to a wreck, the routes followed by bottom fishing are chaotic and insensitive to archaeology and conservation.
The Western Approaches, western English Channel and North Sea have been heavily impacted for over a century. All manner of finds from Palaeolithic axe heads to Second World War airplane propellers have been netted across European waters. The North Adriatic has been devastated. The waters of Sicily, southern Turkey and the Black Sea remain a hot zone where ancient amphoras, statues and even sections of hulls are frequently snagged. Trawlers have pulverised wrecks off Greece, turning them into the marine equivalent of an asphalt highway.
The obliteration of major porcelain cargoes and wooden hulls off Malaysia, Indonesia and Thailand is widespread. Many ships reflecting the history of early American seafaring and seventeenth- to nineteenth-century Spanish colonial trade off Florida, Louisiana, Texas and in the Gulf of Mexico have been heavily eroded by shrimp fishing.
The root of the problem is economic and as such is unlikely to go away: society needs the commitment of hard-working fishing communities as a reliable source of food for a growing population. Currently fishing is conducted with little concern for heritage and is often unsustainable. There is an urgent need for targeted protection for both fish stocks and heritage. Setting large tracts of the seas off limits makes sound financial sense to protect fish communities: the World Bank report, The Sunken Billions, calculated that the major world stocks would produce 40% more if fished less. Marine conservationists have proposed that 30% of the world’s oceans need to be blanketed with mosaics of marine reserves to lift stocks back to sustainable levels.
With so little perceived commercial value, underwater cultural heritage has no comparable economic or political power. Instead, it is an untold wealth of knowledge – the greatest museum in the world – at risk. The vast potential to humanity is almost inconceivable. The organic and metallic shipwrecked artefacts so well preserved underwater, but rarely encountered on land, enhance our appreciation of almost every civilisation that has inhabited the planet.