Over-fishing poses a threat to fish stocks around the world
For centuries the seas have been considered an inexhaustible resource from which people could take as much as they wanted. Now we are having to face up to the fact that our oceans are not limitless - more and more people competing for less and less fish, are which is making the existing crisis worse. Many marine ecosystems are at the point of collapse and will be destroyed unless we act quickly to protect them from the most serious threats.
Over-fishing
Over-fishing is emptying the seas - today's industrialised fishing practices exceed nature's ability to replenish the ocean's fish stocks. According to the United Nations, 71-78 per cent of the world's fisheries are 'fully exploited', 'over exploited' or 'significantly depleted'. Some species have already been fished to commercial extinction; many more are on the verge.
Destructive fishing
Up to a quarter of all the sea creatures caught in global fisheries are discarded - thrown back in to the sea dead or dying - because they are not the fishermen's intended target. These innocent victims of destructive fishing methods are known in the industry as bycatch. They are also known as fish, whales, dolphins, porpoises, fur seals, albatrosses and turtles.
Next time you sit down to a plate of plaice, Dover sole, or other bottom-dwelling fish, imagine that up to three times that amount of other sea creatures (by weight) died in the process of taking them from the ocean - including fish, crabs, sponges and corals. Much of this bycatch is made up of rare and slow- growing species which will take decades to recover, and some of which may be as yet unknown to science.
Whaling
By the time Greenpeace helped to secure an international moratorium against commercial whaling in 1986, many whale populations had been brought to the verge of extinction. In just 60 years Antactic blue whale numbers had plummeted to only one percent of their former abundance, following the introduction of factory ships. As their numbers declined the next largest species, fin whales, were targeted; as their numbers dwindled, the whalers moved on to sei whales. In this way the commercial whaling industry devastated one whale population after another.
Even today, many whale species are showing little sign of recovery. Whales reproduce very slowly, and most whale populations are still nowhere near the size they were before commercial whaling threatened to remove them from our seas for ever. And that threat still remains as Japan, Iceland and Norway continue to ignore international opinion to hunt them.
Climate change
Another serious threat facing marine life is climate change. The oceans and their inhabitants are already being affected by its impacts, which include higher sea temperatures, rising sea levels, and changing currents. As the oceans warm many species have already been forced to migrate into new areas for which they are not adapted and coral reefs, vital habitats on which one in four fish depend, are dying off. If climate change is not checked this process will get worse, and may become irreversible.
Pollution
For decades dirty industries have treated the oceans as dustbins for dangerous pollution. Thoughtless dumping of chemicals, heavy metals, pesticides and other toxins continue to pollute our seas - a direct result of a range of human activities. Once released many of these pollutants accumulate in the marine food chain, posing a major threat to marine ecosystems.
