The Ocean Planet
Deborah Rowan Wright
Originally published by Marinet, 2010
Yawling, Quid and Viviparous Blenney on Gordon Young’s Fish Trail
To see the Earth from space it is a blue planet, a water planet. All life is water based, water driven, and water dependent.
It is difficult to grasp the immensity of the sea. In some parts it is almost 7 miles deep, far deeper than Mount Everest is tall. The sea holds 97 percent of the world’s water, covers 71 percent of its surface, and is home to around 80 percent of all plants and animals.
It is also difficult to appreciate the benevolence of the sea, and easy to undervalue its critical role, and how it makes all life on Earth possible. The constant flow of ocean currents distributes heat from the sun around the globe, moderating otherwise extreme temperatures, and regulating the world’s climate.
The oceans absorb and store huge amounts of carbon dioxide from the atmosphere, more than all the combined plants and forests on land. Some carbon dioxide dissolves into the seawater directly from the air, and the rest is taken up by billions of tiny plants floating on the surface called phytoplankton. These then release enormous quantities of oxygen back into the atmosphere through the process of photosynthesis.
Life in the sea is abundant and fantastically diverse. It is beautiful, mysterious and misunderstood. It can be breathtaking, frightening, and otherworldly. So vast and bountiful is the sea, it has long been regarded as an inexhaustible and indestructible resource.
The Wealth of Britain’s Seas
The seas around the British Isles are among the richest in the world. Colder waters to the north merging with the warmer southern seas, together with a complex underlying geology, have created many different undersea landscapes and marine habitats.
They include cold water coral reefs, sea grass meadows, kelp forests, broad sand and gravel banks, underwater valleys, cliffs and caves, and they range in depth from shallow coasts and estuaries, to the open ocean, over 2000m down to the seabed.
There is as much variety of landscape under the water as there is on land, and the many diverse habitats support a vast treasury of marine life – all colours, shapes and sizes: from micro-organisms like plankton and bacteria, thousands of types of seaweed and algae, fish, invertebrates, and birds, to the celebrated mammals, such as the Bottlenose dolphin and Killer whale. Even the magnificent Fin whale, second only in size to the Blue whale, can be found in UK waters.
The United Kingdom is very much a sea-loving nation. Over centuries seafaring has enabled us to prosper through shipping, international trade and fishing. As an island people, the British have an enduring cultural and for many a spiritual connection with the sea. Many of us have early memories of messing around in rock pools with a net, or of running along the beach trying to dodge the surf. To stand on the cliff edge is a sobering experience, and also a strangely comforting one.
The UK’s EEZ are three times the size of the land. There are estimated 44,000 recorded species of plant and animals living in the sea and on the coastline – and still more are being discovered. And incredibly less than 1% are currently protected by law, in marine reserves. Establishing marine reserves has been proved to be the best way to safeguard the sea and its wildlife. A prime area to be designated a marine reserve, for example, is the Dogger Bank in the North Sea.
The Dogger Bank
The Dogger Bank is a powerhouse of marine life in the North Sea. A huge sandbank of roughly 10,000 square km, it is one of the north Atlantic’s most productive spawning and feeding areas. The clear, shallow waters give rise to high levels of year-round phytoplankton, supporting a massive food web, from microscopic fauna and flora, burrowing worms in the sediment, crabs, flatfish, lobster and starfish on the seabed, to an abundance of fish, including many commercially caught species such as sand eel, herring, whiting, and cod. Mammals there include Harbour porpoise, White-beaked dolphin and Grey seal, while thousands of seabirds (from 24 recorded species), colonise the skies above, among them gannets, storm petrels and fulmars.
Crisis at Sea
Beneath its expansive surface though, the sea is suffering. Decades of ignorance and misuse have resulted in our oceans being seriously damaged and degraded. Precious habitats have been destroyed, fish populations have collapsed and waters are polluted.
There are several causes of this catastrophe, but probably the most significant is the fishing industry: specifically the quantity of fish caught, the methods used, and the casual destruction of unwanted species.
Over Fishing
For decades fishing fleets have been very effective at emptying the seas, and now over fishing has left the populations of many species close to collapse. The scientific evidence shows that 88 percent of commercial stocks are being over fished in EU waters, i.e. to a degree where they cannot replenish themselves, and that 30 percent are being fished to a point where they will become extinct.1 Tuna were once prolific in UK waters, but were fished out in the 1960s. In 1900 six to eight times more cod were caught in the North Sea than today. And this is despite the technological advances which now allow farther and deeper fishing. Cod stocks were then at least ten times greater than they are now.2
Methods of Fishing
Over the past 50 years the technology of fishing has changed enormously. Large factory ships with all manner of fishing gear, able to stay out at sea for weeks, have replaced the traditional small vessels. They can take more and more, go further and further, and reach deeper and deeper. And their sophisticated sonar equipment easily locates their target. Powerful mechanical winches haul in the hefty nets, (which in the case of drift nets can be a mile long). Nets are huge and indiscriminate, catching and killing everything they encounter, including tonnes of unwanted species, (known as bycatch). Scallop and oyster dredging demolishes delicate seabed habitats, and various types of trawl reach wide areas and great depths of the sea. Trawling has been described as the marine equivalent of clear cutting forests to the ground before we even know what is in them. The most iniquitous of all fishing methods though, could be bottom trawling, where immense weighted nets are dragged across the sea floor, crushing everything in their wake. Habitats which take moments to destroy, may take decades to recover. In the southern North Sea, for example, a vast area of the seabed, thousands of square miles wide, which was crusted with oysters and other species, has been left lifeless by trawling and dredging.
The large, older fish have nearly all been taken. They produce the most eggs, and hence many more offspring and so are vital for maintaining the population. A female cod produces eight times more eggs when she doubles in length. But most of the cod caught today are barely mature, and so are virtually unable to reproduce. Cod can grow to over 2m long. The average fish caught in the North Sea in the 1960s was 1.52m long, while the average caught today is less than 50cm long.3
Bycatch
Bycatch is all that is caught and then discarded, dead or dying, back into the sea, because it is not what the fishermen want. Apart from fish and invertebrates, this waste of life often includes dolphins, seabirds, turtles, and seals. Up to 7000 porpoises are killed each year, for instance. The waste is phenomenal and the slaughter is unjustifiable. For example, for every kilo of Dover sole landed, approximately 6 kilos of other sea life is caught and thrown away, including many types of fish, crab, sponge and coral. Some of them are rare and slow growing and their numbers may never recover. WWF has estimated that between 40 and 60 percent of all fish caught by North Sea trawlers are discarded, and that every year at least 1 million tonnes of fish and other sea creatures are thrown overboard, just in this region.4
Other Causes of Marine Degradation
Other causes of marine degradation include the adverse impacts of the oil and gas industries, and the development of off-shore wind farms. Aggregate dredging too has a devastating effect on shallow, coastal habitats. This is the mining of sand and gravel from the sea floor, largely for use in the construction industry. Both sand and gravel sea beds support rich and varied biological communities and are important spawning feeding areas for many types of fish, including commercially caught species. Aggregate sites are often located precisely in these sensitive areas, and intensive and repeated dredging severely damages marine habitats and may destroy them completely, before there value has been recognised.
Pollution
There are many types of pollution at sea. The most well known type is from accidental oil spills such as from Exxon Valdez and the Deepwater Horizon rig in the Gulf of Mexico. Damaging as these disasters are, it is the pollutants entering the sea on a regular and daily basis which are worse. Their long-term, cumulative effect is disastrous for the sea. For instance, eutrophication (caused by fertilisers running off the land into rivers and into the sea), results in increased nutrient levels in the water and makes algae grow rapidly on the surface, which disrupts the balance of the ecosystem and triggers many problems. When the algae die, their decomposition by bacteria uses up the dissolved oxygen in the water, leaving too little for other marine life. The effect has been described as creating ‘dead zones’, as the sea and all life within it simply dies. Other forms of pollution include untreated sewage, toxic chemical discharges from industry, waste from nuclear power stations, dumping, ships flushing tanks and emptying waste, and plastic litter.
This is a huge subject, but here is a brief overview of just one area of marine pollution: The plague of Plastic. Over the past two decades there has been a massive proliferation in the production of plastic: bottles, food containers, bags, netting, six pack rings, packaging etc., Plastic pollution is everywhere and vast quantities are found at sea and on the shore. It kills all types of marine life, as they ingest it, are trapped by it, strangled by it and choke on it. There are 46,000 pieces of plastic per square km floating on the world’s oceans, killing an estimated 1 million seabirds and 100,000 marine mammals every year. Tonnes of tiny granules of plastic, used in the manufacturing process, reach seas and beaches. They harm even the smaller creatures such as barnacles and worms, as they ingest them. Plastic release toxin styrene compounds which contaminate sea life right along the food chain, including the fish we eat. Plastic is virtually permanent. It may take hundreds or even thousands of years to break down. The Great Pacific Garbage Patch is a vast accumulation of plastic debris floating in the Pacific, covering an area twice the size of France.
References
1. EU Commission, Green Paper on Reform of the Common Fisheries Policy 2009
2. Callum Roberts, BBC News December 2007
3. WWF-Germany, ‘Rescuing the North and Baltic Seas: Marine Reserves - a key tool’ 2004
4. WWF-Germany, ‘Sea Creatures Are Not Rubbish’ 2008
5. IUCN, ‘Ocean Blues’ 2006
Deborah Rowan Wright
Deborah Rowan Wright is a freelance writer and Ocean Conservationist. She published her book ‘Future Sea: How to rescue and protect the world’s oceans’ (The University of Chicago Press) in 2020.
She was a Marine Conservation Policy Analyst for Marinet when she authored ‘The Ocean Planet’