Commercial fishing takes heavy toll on sea
Some commercial fishing methods are very harmful to the sea. They can destroy fish habitats and the whole marine ecosystem. Nearly 70 per cent of commercially important marine fish stocks have been over-exploited. Fish are caught faster than they can breed.
Hundreds of kilometres of drift nets used to catch fish also snare seals, dolphins and turtles. Sometimes old nets are dumped in the sea where thousands of fish and marine mammals get caught up and die.
Nets trawled over the seabed to catch bottom-dwelling fish and shrimps may harm corals and stir up sediment. Creatures living on the sea floor die from being smothered in sediment.
Trawlers sweep the seabed several times a year and may increase the sediment suspension by 1,000 per cent. Ecosystems get buried and seagrass beds, a common spawning ground for seahorses, are destroyed.
Long lines with hooks to catch fish in the upper regions of the sea are sometimes dredged over corals, destroying this rich habitat. Also, about 400 albatrosses are killed in the southern oceans every year on long lines.
Nets used to catch small fish also trap unwanted bigger fish. A 1992 study found that about 27 million tonnes of sea creatures were killed by accident in nets.
WWF HK is a local charity environmental organisation established in 1981 which aims to build a future in which people can live in harmony with nature.