Tens of thousands of fish washed ashore along the Texas Gulf Coast as of Friday after being deprived of oxygen in the warm water, officials said.
Brazoria County park officials said a cleanup effort was underway, but thousands more fish were expected to be washed ashore.
Quintana Beach County Park officials released the photos Saturday dozens of dead fish floating in coastal waters.
The cause was a « perfect storm » of poor conditions, said Bryan Frazier, director of the Brazoria County Parks Department.
Warm water contains much less oxygen than cold water, he said, and calm seas and cloudy skies in the area have hampered the way oxygen is usually infused into ocean water. Waves add oxygen to the water, and cloudy skies reduce the ability of microscopic organisms to produce oxygen through photosynthesis.
When schools of fish are trapped in shallow, warm water, they can begin to act erratically as they are starved of oxygen, which further depletes the oxygen in the water.
Katie St. Clair, Marine Life Facility Manager at Texas A&M University in Galvestonhe said warming Gulf Coast waters due to climate change may have contributed to the killing of fish.
« As we see an increase in water temperatures, certainly that could lead to more of these events happening, » Ms. St. Clair said, « especially in our shallow, nearshore or coastal environments. »
The National Weather Service has recorded a maximum of 92 degrees in Brazoria county Friday, the day dead fish were first reported ashore.
Mr. Frazier added that such fish kills « aren’t that uncommon » in the area and begin to occur as the water warms up during the summer.
« It’s a little alarming to see a wave of dead fish wash ashore, » Frazier said. But he added that local water conditions would improve as ocean waves pump oxygen back into the water and as fish swim away from low-oxygen areas.
« Mother Nature has a way of balancing all of that, » Frazier said. « You should correct yourself here in the rather near future. »
A United Nations report completed in 2019 that warming ocean water has 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 loss of oxygen and other effects of global warming would « create enormous pressure” in the Gulf Coast region in the future.
In addition to localized cases of hypoxia, a large « dead zone » of water covering thousands of square miles it is known to form in the Gulf of Mexico during the summer months.
The National Oceanic and Atmospheric Administration forecast for Monday that this year’s dead zone would be smaller than usual, covering about 4,155 square miles of coastal waters.
Ms. St. Clair said the killing of fish could have a significant environmental impact because the dead fish are mainly from the Gulf menhaden — play a « critical role » in the local ecosystem.
« You could see cascading impacts if we continue to have these big fish kills, » he said.
The dead fish began washing ashore in Brazoria County, about 65 miles south of Houston, early Friday morning, Frazier said, and park crews were quickly dispatched to clean up and bury them before they began to rot in the midday heat.
« We have to get them moving pretty quickly, » Frazier said. « It doesn’t take long for them to sit there at 90 degrees to really build up a nasty smell. »