A 1987 study concluded that blast fishing was then very widespread in the Philippines, estimating that 25% of all municipal fish landings (equivalent to 250,000 metric tons per year) were from blast fishing. Most of the blast fishing is however done in the south, near Palawan and the South China Sea. A study conducted in 2002 reported that destructive fishing methods had caused the degradation of about 70% of Philippine coral reefs and reduced annual fisheries production by about 177,500 metric tons in the 1990s.