Miami-Dade County continues to respond to recent fish kill in Biscayne Bay with multi-pronged approach

Miami-Dade County will be conducting underwater surveys of Biscayne Bay on Monday as County staff scientists in the Division of Environmental Resources Management (DERM) continue to investigate a recent fish kill. Among the ongoing actions:

• Collecting and reviewing data, including water temperature, dissolved oxygen levels, nutrients and input from the canals 
• Conducting underwater surveys of bay bottom habitat, including a seagrass investigation in the Julia Tuttle basin 
• Continuing to collaborate with partners to evaluate data 
• Coordinating with the County Parks, Recreation and Open Spaces Department to provide a dumpster for boaters and residents conducting clean-ups of fish carcasses at Pelican Harbor Marina 

“We are committed to taking swift action to protect the ecological gem that is Biscayne Bay,” said Miami-Dade County Mayor Carlos A. Gimenez. “This time of year the marine life in our bay is susceptible to high heat levels, and we want to make sure we understand the causes of this most recent incident so that we can as quickly as possible restore conditions so that our marine life can continue to thrive.” 

Since last week, DERM staff have  been collecting and evaluating water quality data from the bay and canals and evaluating flows from the regional canal system into the bay to better understand the cause of and conditions that contributed to this recent event.  

The fish kill occurred primarily in the Julia Tuttle basin, which lies between the Julia Tuttle Causeway and the JFK Causeway, and extended south toward the Venetian Causeway. The basin is already in a distressed state due to seagrass die-off, where DERM found that over 75% of the seagrass has been lost in a 2019 study, "Report on the Findings of the County's Study on the Decline of Seagrasses and Hardbottom Habitat in Biscayne Bay." This is likely a contributing factor to the fish kill, along with very high water temperatures and exceedingly low dissolved oxygen levels in some areas, as seagrasses are key to helping oxygenate the water.  

Over the weekend, two Miami-Dade Fire Rescue boats from PortMiami joined in response efforts by deploying to select spots within the Julia Tuttle basin in an attempt to aerate the water to provide more oxygen. The Parks, Recreation and Open Spaces Department helped secure the dumpster at the marina. The City of Miami has also deployed the Scavenger 2000 vessel to oxygenate the water. In March of this year, the Board of County Commissioners approved for a second year a $140,000 contribution to the Miami River Commission to pay for the Scavenger vessel that collects floating debris in the Miami River and aerates the water. 

Among the partners DERM is working with are the Florida Department of Environmental Protection - Biscayne Bay Aquatic Preserves, Florida Sea Grant Extension-UF/IFAS Extension Miami-Dade County, NOAA, FIU, UM, Florida Fish and Wildlife Conservation Commission, Miami Waterkeeper and Pelican Harbor Seabird Station.