The eruption of Chile's Calbuco volcano threatens to cause widespread, lasting economic damage, turning cattle pastures barren and choking fish with volcanic ash in one of the world's top salmon-producing countries.

Ema Budinich of the National Agriculture Society said Tuesday that the eruption is forcing the evacuation of thousands of cattle and sheep at risk of dying in Los Lagos. The region produced about 950 million liters of milk last year worth about $346 million.

Official estimates are not available yet, but Eduardo Aguilera of the National Fishing Service says about 20 million fish have died.

Calbuco erupted Wednesday, billowing ash about 11 miles (18 kilometers) high, followed hours later by a second, spectacular outburst. Some 4,500 people have been evacuated.