PORT SALERNO, Fla. - It's a different world, 75 feet under. At least, it feels that way at Six Mile Reef, just off Stuart's coast.
It's a world that's been threatened by the fish diver Rick Dahn is hunting: the beautiful, exotic lionfish.
Dahn and four other divers boarded the boat, "Irish Rover" in Port Salerno at dawn Saturday and motored away, for the 2nd Annual Lionfish Round-up.
Captain Kerry Dillon directed the crew right above the natural reef. They geared up and plopped in the water, with hopes of making a small dent on a big problem.
"We got underwater, and there they were. Lionfish. Every 20, 30 feet another lionfish," said Dillon, who owns Sea Rover Services.
The group speared the fish for several hours. The divers collected the spiny animals in mesh bags and hauled them on deck. Dillon's finger swelled up, after he says a spine stuck him.
Scientists say the venomous fish may have changed eco-systems forever.
Lionfish are an invasive species that showed up about 20 years ago in small numbers, according to Dr. Jim Masterson. He's a biologist at Florida Atlantic University's Harbor Branch Oceanographic Institute in Fort Pierce.
"It's not supposed to be here," he said of the fish. It's non-native and has no natural predators. Dr. Masterson says the fish might be out-competing other animals and eating the next generation of important fisheries before they can mature.
"Our fear is that large numbers of lionfish might be taking more than their fair share," said Dr. Masterson.
Captain Dillon says the fish is known to eat a lot, without much discretion for what it consumes.
Dillon has dove in Martin County reefs since 1979. He says the first time he saw a lionfish here was four years ago. Now, he says he sees one of the alien invaders on almost every dive.
"They've been around here for enough years now we're seeing the decrease of other species," said Dillon.
Florida Sea Grant says they're becoming increasingly common on the Treasure Coast. Smithsonian Magazine reports the fish may have hurt tourism and commercial fishing.
The huge problem may have improved a tiny bit, when the local crew turned in about 40 lionfish.
"We cleaned house, did a service to the eco-system and just had fun," said diver Hollis Dahn, who studies biology at the University of Central Florida.
Other divers and anglers contributed 80 more lionfish. That makes for almost 120 less lionfish in reefs along the Treasure Coast and Palm Beaches.
The event today was connected with the Reef Builders Tournament, both of which benefit Martin County's artificial reefs.
One method of controlling the lionfish population is eating. The National Oceanographic and Atmospheric Association (NOAA) has held campaigns to introduce the fish as food.
But earlier this week, Florida Sea Grant advised against that, saying the fish could cause a food-borne illness called ciguatera. It says the toxins do not break down using conventional cooking methods.
Dr. Masterson says getting ciguatera poisoning is a risk you take when you eat fishes off of tropical and sub-tropical reefs. He says the toxins are not exclusive to the lionfish.