Due to overfishing, reef fish populations have been greatly decreased in some areas of the world. The removal of large numbers of reef fish has caused the coral reef ecosystems to become unbalanced and allowed more competitive organisms, such as algae, which were once controlled by large fish populations, to become dominant on reefs in many regions. Due to decreased yields, fishermen have been forced to change their methods in order to catch enough fish to sustain their needs. In some areas this means fish traps with small mesh diameters which catch even the small juvenile fish. Not only do these practices kill all fish in the affected areas, but they also severely damage the corals in these areas.
Corals are also very popular as decorations.
Often, when people vacation in tropical locations surrounded by beautiful reefs they want to take coral souvenirs home. These shops receive their corals from commercial collectors who select well developed colonies which will make them the most money. This is very damaging because a large amount of the most healthy corals are selected. Coral reefs also receive much damage from both commercial and private vessels. The leakage of fuels into the water and the occurrences of spills by large tankers are extremely damaging to local corals.