Threats: Trashing our oceans

Publication - April 8, 2008
Millions of tonnes of trash are swirling around our oceans, originating from land and sea. Plastic is believed to constitute 90 per cent of all garbage found in our oceans, with every square kilometre of ocean containing almost 120,000 pieces of floating plastic according to UN estimates. Plastic is particularly ubiquitous and problematic because of its durability.

It does not biodegrade, but simply breaks into smaller and smaller particles that are then ingested by a variety of marine life, from plankton to marine turtles. As plastic accumulates in their digestive tract, animals are gradually choked or starved. Plastic also acts as a sponge for some of the worst toxins, persistent organic pollutants (POPs), adding to the toxic burden of marine life.

Over 100 million tonnes of plastic are produced each year, and it is estimated about 10 per cent of this makes its way to the ocean. As various plastic products are tossed by waves and wind, they gravitate towards calm spots in the ocean, creating areas with high concentrations of floating debris. In the North Pacific, a well-documented “trash vortex,” estimated to be the size of two times the U.S. is slowly swirling, with an astounding six kilograms of trash estimated for every kilogram of plankton!

Roaming trash is also a serious problem. Discarded or lost fishing gear float through the oceans, continuing to snag and drown cetaceans and sea turtles for years. As pieces of trash travel on the currents, various organisms jump aboard and sail into habitats where they can quickly become pests.

The irony is that the vast majority of this trash comes from land-based sources. About 80 per cent of the trash originates on land, with the other 20 per cent coming from commercial, recreational or military vessels and offshore oil and gas platforms.