Speaking at an international seminar on coral reefs and marine protected areas in Johannesburg in South Africa Monday, Alvarez said a tenth of the Earth’s coral reefs has been destroyed and nearly one third seriously damaged.
"As breeding grounds and nurseries of fish, coral reefs are major food resources and bulwarks of food security," he said. "Marine environmentalists... supply a fifth of all animal protein consumed by the world’s population. They provide food for over a billion people in Asia."
Alvarez said the following has "wreaked havoc" on coral reefs: Destructive fishing methods, overfishing, coral mining, inland sedimentation and pollution, oil spills, land reclamation and high population growth.
Alvarez said more than 60 percent of the world’s 200 main fish stocks and 11 of 15 major fishing grounds have been "fully exploited and overexploited," and have been depleted.
"Global fish catch has declined from a peak of 90 million tons per year, starting in the 1990s due to coral reef degradation and overfishing," he said.
Alvarez said the drop in the number of fish caught in the Philippines during the past 10 years have threatened to bring down the available fish for every Filipino yearly, from 24 to 10 kilos by 2010.
"Less fish caught means less protein and less nutrition for more people around the world," he said.
Last year, Alvarez signed Department Administrative Order No. 17 which reserved a 15-kilometer area in waters off the country’s coasts for the exclusive use of local fishermen.
The order encouraged commercial fishing beyond the 15-kilometer boundary.
The Reef Check Foundation has reported that sea food resources like lobster have "significantly declined" in the Atlantic, Pacific and Indian Oceans, and the Red Sea between 1997 to 2001.
Following El Niño occurrences, live coral cover has been reduced by 10 percent, which means that coral reefs are "sensitive indicators" of global warming, the report added.