The Gulf of Mexico’s “dead zone”—an area with little or no oxygen—is 7,085 square kilometers this year, 21 percent less than previous estimates and the fifteenth lowest on record.
This equates to approximately 1.1 million hectares of potentially unavailable habitat for fish and bottom-dwelling species, a 30 percent reduction from the previous year, according to NOAA.
Scientists from Louisiana State University and the Louisiana Universities Marine Consortium (LUMCON) led the annual dead zone survey from July 20 to 25 aboard LUMCON’s research vessel Pelican. This annual measurement is a key metric informing the collective efforts of the Mississippi River/Gulf of Mexico Hypoxia Working Group, which has set a long-term goal of reducing the five-year average dead zone extent to less than 3,000 square kilometers by 2035.
ENCOURAGING SIGN
This year’s significant reduction in the Gulf of Mexico’s “dead zone” is an encouraging sign for the future of this area, said Laura Grimm, NOAA’s acting administrator.
“This underscores the dedication and important work of NOAA-supported scientists and partners and serves as a testament to the effectiveness of collaborative efforts to support our fishermen, coastal communities, and vital U.S. marine ecosystems. We are proud of these accomplishments and remain committed to advancing research and strategies that ensure the health and vitality of our oceans for future generations,” she said in a statement.
In June, NOAA predicted a dead zone averaging 8,970 square kilometers in size, based primarily on Mississippi River discharge and nutrient runoff data from the U.S. Geological Survey. The measured size fell within the uncertainty range of the NOAA ensemble forecast, demonstrating the overall accuracy of the underlying models and their value in guiding nutrient reduction strategies.
While each NOAA-funded research study provides a snapshot of the dead zone, the five-year average captures the changing nature of the zone over time. The average size of the dead zone over the past five years is currently 7,652 square kilometers.
Excess nutrients from the Mississippi-Atchafalaya River Basin stimulate excessive algal growth in the Gulf of Mexico. When these algae die and decompose, they deplete the water of oxygen as they sink. The resulting low oxygen levels (hypoxia) cause marine life, such as fish and shrimp, to abandon the zone. Exposure to hypoxic waters has been found to alter fish diets, growth rates, reproduction, habitat use, and the availability of commercially caught species such as shrimp.
