The world's seas and oceans are being polluted by

• Agriculture - The run off of pesticides and fertilisers
• Industry - effluent from factories and power stations
• Sea transport - especially oil tankers
• Overfishing - a type of pollution as it damages the environment
• Domestic waste - sewage from settlements

Ocean pollution can kill fish, plants and animals, spoil beaches and swimming areas, and make people ill.

Ocean pollution can be prevented by banning the use of the dangerous forms of agricultural chemicals, building sewage treatment plants, using aircraft to follow and monitor ships, and using laws to stop industry dumping waste in the rivers and seas.

Overfishing

With overfishing too many fish are caught and the number of fish in the sea decreases substantially. Overfishing could be prevented by

• Putting quotas on much fish can be caught
• Banning nets with small mesh size and using square mesh panels. This allows smaller, immature fish to escape, grow and breed
• Tie-up schemes. Boats are only allowed to fish on so many days a month
• Decommissioning. Fishermen are encouraged to stop fishing by getting compensation for their old boats
• Exclusion zones. Areas of the sea are off-limits to certain nationalities, or at certain times of the year
• Monitoring by Fisheries Protection ships and aircraft. Larger fishing boats are now required to carried devices so that their position can be monitored by satellite.