PUNTA GORDA -- Steve Brookman's pond attracts the undesirables.
Brookman dug the half- acre pond about three years ago in the middle of his 10-acre spread in Alva, just east of North Fort Myers, and filled it with a variety of native fish species -- gar, sunfish and bass.
Brookman basically forgot about the pond and the fish for the next 11/2 years. But his next inspection provided an "Oh my god" moment.
The fish traps he had placed in the pond caught "all these weird species," Brookman recalled. Jewelfish, black acaras, Mayan cichlids and armored catfish abounded.
Despite no discernible point of entry into this isolated pond, the fish, which are all non-native species from Africa and South America, had infested it.
"It got out of hand," said Brookman, co-founder of the Southwest Florida Aquatic Nuisance Species Surveillance and Education Network. "I stopped counting the (jewelfish) when I got to 300."
Local scientists say the problem is out of hand across the state: Potentially dangerous exotics are invading the South Florida waters, and their ranks are steadily growing.
"Florida nearly leads the country in the number of non- indigenous fish (53 species, only California with 56 has more) that have established themselves in these waters," said John Cassani, the network's program manager.
Many of the species, such as the jewelfish and armored catfish, thrive in South Florida rivers and creeks. Their numbers have exploded, scientists say, and the potential for harm to the native ecosystem is great.
More is known about the state's freshwater exotics, which have been better studied and documented than their saltwater counterparts. Scientists say, however, that exotics in the Gulf carry the same potential to disrupt ecosystems by outcompeting native species, preying upon them, disrupting habitats, or spreading disease.
Scientists from Sarasota to Naples gathered on Thursday in Punta Gorda at the Charlotte Harbor Preserve State Park to discuss the problem. The implications are serious.
The rate of introductions in U.S. waters has increased "exponentially since the 18th century and shows no signs of leveling off," states a report prepared for the Pew Oceans Commission, a nongovernmental marine policy think tank. In some ecosystems, the "introduced species can become so dominant that finding native species becomes an elusive task."
And the problem is not just a South Florida exclusive. Invasions of these exotic species are now recognized as being second only to habitat destruction as a cause of global extinctions, according to a 2002 report issued by the National Oceanic and Atmospheric Administration.
In Florida, the problem is exacerbated by heavy rains, which create a sort of high-water highway across the south and allow fish to travel to seemingly unconnected water bodies such as Brookman's pond.
"Basically, anything south of Lake Okeechobee is connected through a series of wetlands," said David Ceilley, director of Conservancy of Southwest Florida's environmental science division. "And some fish can move through those pathways with ease."
Proof of the problem
The evidence of this spread is clear, scientists say, noting numerous examples.
The brown hoplo, or armor- plated catfish, for one, appears to have spread from the east coast to the west via these ephemeral waterways.
The fish was first reported in 1995 in the Indian River Lagoon. It has since spread across the state in abundance. The Peace and Myakka rivers are now infested.
"All indications are that it is throughout Southwest Florida now," Ceilley said.
Another species of immediate concern is the Mayan cichlid, an exotic species from Central America, which Mote Marine Laboratory researchers discovered in Charlotte County for the first time in July.
The fish, a native of South America, is aggressive and multiplies quickly, possibly forcing out native species. Even more troubling is the concern that the cichlids, which appear to thrive in the brackish waters of Charlotte Harbor, could be preying on juvenile game fish such as snook, redfish and tarpon and causing a decline in their numbers.
No one is certain how the cichlid or most of the other species arrived in Florida. Some postulate, however, that the fish may have escaped from fish farms.
The state is one of the largest producers of tropical fish, with roughly 200 tropical fish farms statewide (most are in Hillsborough and Polk counties). Tropical fish are the number one air cargo export out of Tampa International Airport, with an estimated 12,000 to 15,000 boxes of fish moving through weekly.
Others fear that fish owners release the fish into the local waterways when they outgrow aquariums. Once introduced to the warm, food-rich Florida waters, many, such as the oscar, thrive.
The oscar, a popular aquarium fish, proliferated across South Florida and became especially abundant in the Everglades. The lure of catching one of these popular aquarium fish drew fisherman from around the globe.
The Internet adds to the troubles by making undesirable and often dangerous fish available to the masses, said Dr. James Carlton, who authored a report on marine invasions for the Pew Oceans Commission.
"Just look what you can order off the Web and have delivered to your office the next day," Carlton said. "It's scary."
Some introductions may be intentional, however.
"If it's good for angling, people will spread them around to other ponds," said Kirby Wolfe, a senior biologist with Mote Marine Laboratory.
'They're not all bad'
Not everyone condemns these introductions.
"People can jump up and down and get all excited about non-native species, but sometimes these species are a good thing," said "Fishin'" Frank Hommema, a local guide.
Some of the fish, such as the tilapia and oscars, are "a ball to catch and good eatin' too," said Hommema.
"Not all the non-indigenous species are great," Hommema said. "But they're not all bad, either."
It is estimated that more than 130 species of fish have been introduced in Florida waters, of which 53 have established breeding populations.
However, true numbers are elusive, and Florida remains one of the least-researched areas in the nation, said Carlton, who serves as director of maritime studies at Williams College in Massachusetts.
No one can say with any certainty what impacts these migrants have had or will have on the ecosystem. At best, scientists' understanding of these systems is incomplete.
"We need to do a better job of documenting the impacts of these species," said Chris Becker, an environmental specialist with the Florida Department of Environmental Protection.
Becker notes that worry abounded in the 1970s that the walking catfish, an exotic, which is native to Asia, would decimate local fisheries. It never happened.
"But what happens when you add the catfish with something else that eats vegetation?" Becker asked. "And then you add more and more fish over time. What is going to be the straw that breaks the camel's back?"
Removing those straws is difficult, if not impossible, scientists agree.
"Once an exotic species is in a body of water it's really hard to get rid of," said Kirby Wolfe, a senior biologist at Sarasota's Mote Marine Laboratory.
Preventing future introductions has become the prime goal. Educating the public through seminars and printed materials is key.
"You can talk a lot about the species that are already here," Carlton said. "But you have got to shut the door and stop new ones from entering the system. Otherwise, it's as if there was a rainstorm and all the windows are open and you are mopping it up.
"That's about where we are now."
I thought this was an interesting article since it pertains to Cichlids