From Farmer to Shrimper: The Dead Zone
(pg 1 of 8)

Twenty years ago, Louisiana fishermen netting the Gulf of Mexico for shrimp noticed their nets were bringing up less and less-except the stench of decomposition.

Further study revealed a growing "dead zone" spreading from the mouth of the Mississippi across the Louisiana-Texas shelf of the Gulf. Dissolved oxygen along the seabed often dipped to less than 2 milligrams per liter, driving away fish and stressing or killing organisms, such as crustaceans and shellfish, that couldn't flee.

The dead zone developed each spring and summer. It varied in size from year to year, once growing to 8,500 square miles, about the size of Massachusetts.