After a messy first year at their new location on Virginia Key, Ultra organizers are pulling out of the venue bordering sensitive wildlife areas and the University of Miami's Rosenstiel campus.
The Miami Herald reported organizers sent a letter to the city Wednesday saying they wanted out.
The decision comes a day before city commissioners were scheduled to vote on whether to allow the thunderous three-day music festival to return next year.
The controversial move to Virginia Key came after Miami nixed plans to hold the festival, one of the largest in South Florida, in Bayfront Park, its home for nearly two decades. The event's high-volume acts drew bitter complaints from Miami's increasingly residential downtown.
But moving to Virginia Key also raised concerns. Organizers erected two stages: one near Marine Stadium bordering a protected wildlife area used by manatees and nesting wading birds, and another on the beach near nesting sites for endangered crocodiles and turtles. Environmentalists and UM researchers worried that high noise levels along with crowds expected to reach over 40,000 would damage the fragile surroundings.
A study conducted by University of Miami scientists after the March festival found stress levels in the fish spiked during the three-day event. It's likely other valuable research fish also suffered, they said.
"It was three days, back to back, 12 hours of music every day," Martin Grossell, an ichthyologist with UM's Rosenstiel School of Marine and Atmospheric Science, said this week. "As far as I know, that exceeds anything we've had out here before."
Before the March concert began, researchers recorded noise levels in tanks for toadfish. Toadfish are plentiful in Biscayne Bay and used for research because they are hardy and changes can be easily detected.
For about seven hours during the concert, researchers again recorded the sound in the tank and then measured the level of stress hormones in the fish. They were about four times higher than normal, and equal to what the fish would feel if they were being chased by a bottlenose dolphin.
"Under those conditions, after seven hours of Ultra, they experienced an increase in stress hormone levels. And we have seen in other studies that this would disrupt behavior," said UM marine biologist Danielle McDonald.
Because the fish consider the loud sounds a threat from a possible predator, males stop making their distincitve calls to attract females, which can disrupt their mating season. McDonald said mating season typically begins in March.
Because the study focused on research fish housed on the campus, McDonald said it's not clear if the noise harmed wild fish. However, other valuable research fish nearby, including cobia, hogfish and grouper, also likely experienced the same stress, she said.
The Herald reported that festival organizers are now considering a move to the Homestead Speedway.