Tens of thousands of fish washed up along the Texas gulf coast as of Friday after being deprived of oxygen in warm waters, officials said.
Park officials for Brazoria County, which is about 65 miles south of Houston, said a cleanup effort was underway but thousands more fish were expected to wash ashore.
Quintana Beach County Park officials released photos Saturday showing dozens of dead fish floating in coastal waters.
The cause was a “perfect storm” of bad conditions, said Bryan Frazier, the director of the Brazoria County Parks Department.
Warm water contains much less oxygen than cold water, he said, and calm seas and overcast skies in the area had hindered the way oxygen is usually introduced into ocean water. Waves add oxygen to water, and cloudy skies reduce the ability of microscopic organisms to produce oxygen through photosynthesis.
When schools of fish become trapped in shallow, warm water, they can start behaving erratically because they are deprived of oxygen, further depleting the oxygen in the water.
Katie St. Clair, the manager of the marine life facility at Texas A&M University in Galveston, said warming gulf coast waters from climate change could have contributed to the fish kill.
“As we see increased water temperatures, it could certainly lead to more of these events,” said Ms. St. Clair, “especially in our shallow, nearshore or coastal environments.”
The National Weather Service recorded a high of 92 degrees in Brazoria County on Friday, the day the dead fish were first reported washing up.
Mr Frazier added that such fish kills are “not that uncommon” in the area and begin to occur when the waters warm up in the summer.
“It’s a bit disturbing to see a wave of dead fish washing up,” Mr Frazier said. But he added that local water conditions would improve as ocean waves return oxygen to the water and as fish swim away from low-oxygen areas.
“Mother Nature has a way of balancing that out,” Mr. Frazier said. “It should correct itself here in the near future.”
A 2019 United Nations report concluded that warming ocean waters had increased the incidence of hypoxia — or low oxygen levels — in coastal waters, threatening fish populations. One of the report’s authors said at the time that oxygen loss and other effects of global warming would “put tremendous pressure” on the Gulf Coast region in the future.
In addition to localized instances of hypoxia, a large “dead zone” of water covering thousands of square miles is known to form in the Gulf of Mexico during the summer months.
The National Oceanic and Atmospheric Administration predicted Monday that this dead zone would be smaller than normal this year, covering about 4,155 square miles of coastal waters.
Ms. St. Clair said the fish kill could have a significant impact on the environment because the dead fish – mainly Gulf Menhaden – play a “critical role” in the local ecosystem.
“You could see cascading effects if we continue to have these big fish kills,” she said.
The dead fish began washing up in Brazoria County early Friday morning, Mr. Frazier said, and park crews were quickly dispatched to clean them up and bury them before they began to rot in the midday heat.
“We need to get those moved pretty soon,” Mr. Frazier said. “It doesn’t take them long to sit there in 90-degree heat to really kick up an unpleasant odor.”