Texas A&M University oceanography Professor Steve DiMarco says he and other researchers analyzed the gulf from Aug. 15-21 during a 1,200-mile cruise from Texas to Louisiana.
The team found no hypoxia off the Texas coast while only finding hypoxia near the Mississippi River delta on the Louisiana coast, a Texas A&M release reported Thursday.
Hypoxia is when oxygen levels in seawater drop to levels that can potentially result in fish kills and harm marine life.
Agricultural run-off of fertilizers and pesticide into rivers that run into the gulf are often cited as the cause of such "dead zones," researchers said.
"In all, we found about 1,580 square miles of hypoxia compared to about 3,400 square miles in August 2011," DiMarco said.
"What has happened is that the drought has caused very little fresh-water runoff and nutrient load into the gulf and that means a smaller region for marine life to be impacted."
During the past five years the dead zone has averaged about 5,700 square miles and has reached as high as 9,400 square miles, the researchers said.