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FGCU researchers say dead fish from red tide can be turned into natural fertilizer

Posted at 3:56 PM, Nov 05, 2021

FORT MYERS, Fla. — Red tide has had damaging impacts on our marine life and economy over the last several years, but researchers at Florida Gulf Coast University and Mote Marine Aquarium are working to turn the bad into something positive for the future by turning dead fish into eco-friendly fertilizer.

The project is part of the Florida Red Tide Mitigation & Technology Development Initiative, led by Mote Marine Laboratory in collaboration with FWC.

The first thing they looked at was whether or not removing the fish kills early on prevented the algal blooms from getting any worse.

“Red tide can kill the fish, as the fish decay they release the nutrients back in the water that can feed back into red tide,” said Dr. Mike Parsons, Professor of Marine Science at Florida Gulf Coast University.

What they found was that removing dead fish did ensure they weren’t just adding fuel to the fire.

“What we found was that fish are in fact releasing a lot of nutrients," said Parsons.

But then once you remove them, they wondered if there was something else they could do with the tons of dead fish, other than sending them off to a landfill.

“We can compost the fish and remove the red tide toxins from them, and they look like they can be a good fertilizer source,” said Parsons.

A fertilizer source that’s natural, so if it ends up back in the Gulf water down the road, that’s where it came from in the first place.

But of course, these are only things that can be done if the economic impacts are worth the work. So they did an economic study, too.

“For Lee County and Collier County, when red tide was significant, greater than 100,000 cells per liter, which is when fish start dying, that it had an economic impact of $19 million per month in 2018 and 2019,” said Parsons.

$19 million in tourism down the drain due to red tide. So if the dead fish clean-up costs less than the loss in tourism dollars, then it’s worth it.

From what they could find, removing dead fish costs a few thousand dollars per ton of dead fish.

“I don’t think it’s gonna cost $19 million though, I think it’s got a lot of promise to move forward and look at the scale up costs,” said Parsons.

Parsons says the next steps are to bring different stakeholders and municipalities to the table to see if this can be an option moving forward.

“It’s an optimistic approach. It’s doing something about red tide which I think is good,” said Parsons.