Out of sight, out of mind. Most of us have little clue what goes on out there in the big Ocean and it’s easy to turn a blind eye. But the environment, the animals and people suffer the consequences of our inconsiderate behaviour.


One of the major threats to the Ocean and its inhabitants has to do with our food production system. That is, where the food we eat comes from and how it ends up on our plates.

To get fish on the table it needs to be taken from the sea in one way or another. That is obvious, but what is less obvious is the magnitude of destruction that comes along. With large scale industrial fishing techniques and a never ending appetite for more, and then some, we are emptying the Ocean. Killing the life within it. Taking away the very essence of that which makes the Ocean so breathtakingly beautiful, so marvellous and mysterious, so full of diversity and colour, and like nothing else in this world.

We are simply overfishing the seas. Taking more than the Ocean can give. It is unsustainable, destructive and threatens many species to extinction. In fact, all large predatory fish populations have been diminished by 90 percent, including tuna, cod, halibut, sharks and swordfish, and 85 percent of the world’s fisheries are being pushed to their limits. Although some countries are improving their fishing methods and some fish populations are recovering, the general picture is depressing.

Losing Nemo is a creative animated short film telling the story of how industrial fishing impacts the Ocean. Watch it now and get the bigger picture.

© Losing Nemo, The Black Fish


Many large-scale, commercial fishing methods cause harm to much more – and many more – than the fish in target.

Billions and billions of fish suffer slow deaths in the fishing industry every year. Many bleed to death from being caught by longline hooks and many are crushed or injured by fishing nets. The fish that are still alive when they reach the surface either get their gills cut and bleed out or they slowly suffocate. What is more, high numbers of unwanted fish and other marine animals are caught in the nets and thrown back in the sea as discard.

Commercial fishing techniques include fishing with drift nets, gillnets, purse seines, trawls, longlines and more.

oydileggjandi© Ingi Sørensen

Drift nets and gillnets work as big walls of net that catch fish by their gills or other body parts in the meshes. One net can be up to several kilometers long. Some nets drift out at sea for days, which means air-breathing mammals caught by accident are left to drown.

A purse seine is a wall of net that encircles schools of fish and closes at the bottom to prevent the fish from escaping. Naturally, many non-targeted species are caught in the net too.

In trawling a large net is pulled through the water by one or two boats. One net can catch up to 7,000 tonnes of fish. The opening of the net can be up to 23,000 square meters.

A longline is geared with hundreds of thousands of hooks and can be up to 100 km long. That is the distance between Earth and outer space!

Bottom trawling is one of the most destructive fishing methods. It is common to use when catching shrimp and other fish that live on or near the ocean floor. Pulled by a fishing trawler, a huge, heavily weighted net is dragged along the sea floor, destroying coral reefs and taking away most life in the range. The amount of bycatch is thus very high, in some cases up to 90 percent of the total catch. What is more, the net disrupts large amounts of sediment that may be polluted and which makes the water uninhabitable. The impact can even be seen from space av.

Other particularly destructive fishing practices include cyanide fishing, dynamite fishing and muroami fishing. These are all methods that cause a lot of damage to the natural environment as well as marine life.


The fishing industry is what causes more deaths among whales, dolphins and porpoises than any other human activity. More than 300,000 cetaceans are killed in bycatch every year. That is almost 1,000 every day!

What is bycatch exactly?

Bycatch is the catch of non-targeted marine animals during fishing. Say you are fishing for cod and a dolphin is caught in the net – the dolphin is then bycatch. What happens to bycatch? Most are thrown back into the sea as discards – dead or dying.

Cetaceans are far from the only species caught in nets unintentionally. Actually, most species of marine mammals have been caught in some type of fishing gear at one point or another. The yearly numbers include 100 million sharks, 300,000 seabirds and 250,000 turtles. It is also estimated that at least 40 percent of ALL fish caught globally is bycatch!

© Bijvangst, The Black Fish


Humans cause a lot of trouble for the inhabitants of the ocean by polluting their home with pesticides, herbicides, chemical fertilizers, detergents, oil, sewage, plastics and other waste.

Toxic chemicals can travel far and wide through wind and water. Arctic regions are contaminated by chemicals from sources thousands of kilometers away. The effects on living creatures is devastating. These include birth defects, reproductive problems, developmental defects, hormonal disturbances, immune system deficits, cancer and other illnesses, and of course early deaths.

Persistent organic pollutants (POPs) is the collective term for toxic chemicals that resist biological and chemical breakdown. These substances stay in the environment from decades to centuries and accumulate in organisms and the food chain. Examples of POPs include the infamous insecticide DDT, PCBs used as coolants and insulating fluids, PBDEs that exist in most plastic products, and dioxins that are by-products of various industrial processes and combustion.

Even though many substances have long been banned by many countries, a number of pollutants are still being used legally or illegally – and new ones arise. Because cetaceans are apex predators and have a poor ability to detoxify they have particularly high amounts of toxics in their system. What’s more, the mothers transfer contaminants to their calves during pregnancy and through lactation.

Another toxic issue is heavy metal poisoning. Heavy metals like mercury, cadmium and lead are hazardous to the environment as well as animals and people. The sources of these toxic heavy metals include the burning of fossil fuels, mining, metal processes, and industrial waste dumping.

Oil spills are a major threat to marine animals and their habitat. Oil is toxic to most forms of life, whether ingested, inhaled, or externally exposed to. Many animals affected by an oil spill die from poisoning sooner or later. Birds and furry animals lose their ability to keep warm and are therefore extra vulnerable. Carnivores risk injury to internal organs if they eat oil polluted prey. It can take years to clean up after an oil spill and much longer, before animals fully recover.

dalking© Ingi Sørensen


© Plastic Soup Foundation

Plastic is everywhere. In the Ocean, on land, in cosmetics, in cows, and even in honey. 10 percent of all waste produced globally is plastic. When plastic is not disposed of properly it ends up in the environment and breaks down into microplastic. Plastic can take forever to biodegrade – especially if it is buried in a landfill or has reached the deep sea where there is no sunlight.

We produce more than 250 million tonnes of plastic every year and about half of it is used once and then trashed. Think for instance of plastic bags, plastic bottles and product packaging. Industries, cities and people are dumping their waste and much of it ends up in the Ocean, where it flows with the currents and accumulates in the major 5 gyres. An average of about 12,000 tonnes of plastic finds its way to the Ocean every day!

For animals the amount of waste is detrimental. It is estimated that 100,000 marine mammals and at least a million seabirds are killed by marine debris every year. Animals get entangled or mistaken plastic waste for food. Many whales and dolphins have been found dead, stranded or in distress after having swallowed debris.

A particular waste issue is ‘ghost fishing’ – when abandoned, lost or discarded fishing gear continues to fish. Most fishing nets and lines are made from synthetic, degrade-resistant materials like nylon, which is a plastic product, instead of hemp or cotton like in the old days. In a deep water fishery in the north-east Atlantic around 25,000 nets may be lost or discarded per year. Nylon nets can continue to fish for hundreds of years, being the cause of death for thousands of marine animals.


What goes on in the vastness of the Ocean is unseen – and unheard – by most of us. But marine animals suffer. The whales suffer.

The levels of human-generated noise has doubled every decade for the past 60 years in many marine areas. More intense ship traffic, high performance military sonars, and seismic airguns used for oil and gas exploration all has a life threatening effect on marine life. Especially cetaceans are under threat.

Sound is extremely important to whales and dolphins. They depend on sound to navigate the oceans, locate their prey and find mates. All that human-made underwater noise works as an acoustic ‘fog’ for the whales, causing them to mass strand and collide with ships.

In addition, some of the sounds from sonars and airguns are so loud that they cause hearing loss, internal injury and decompression sickness. Many whales and dolphins die and sink to the ocean floor, unnoticed by humans. Strandings are just the tip of the iceberg.

Check out this video to get a clearer picture of how whales are affected by noise pollution.

© Underwater Noise – The Overlooked Catastrophe hjá OceanCare

Marna OlsenOcean Threats