How do some non-native fishes help us?
Poster presented May 1999, at the South Florida Restoration Science Forum
Butterfly peacock fish
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The most popular gamefish in southeast Florida canals is the butterfly
peacock. Most people who have an interest in freshwater fishing have heard
of this fish, although they may be unaware that the Fish and Wildlife
Conservation Commission is responsible for
this fabulous fishery. The butterfly peacock is a tropical fish from South
America and it cannot survive in water temperatures below 60 degrees F.
Thus, the distribution of this fish is mostly limited to the manmade canals
in the metropolitan Miami to West Palm Beach area.
After years of study, scientists at the Non-Native Fish Research proposed,
received approval, and effectuated the introduction of the butterfly
peacock which has since helped reduce the number of undesirable exotic
fishes. Furthermore, the butterfly peacock now provides millions of hours
of fishing pleasure for thousands of anglers who spend more than $8 million
annually to catch this fish. Although introductions of
exotic species is never a panacea, this introduction has had significant
benefits.
Florida Non-Native Fisheries Laboratory
Manager: Mr. Paul Shafland
paul.shafland@myfwc.com
561/391-6409 / Fax: 561/391-6619
| Update: August 24, 2008
Feature article written by Steve Reilly, Staff Writer with the Charlotte Sun. Posted here with permission. Thanks to Bob Mooney for his assistance in getting the materials for this article.
Contact the writer: reilly@sun-herald.com
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Nonnative fish called 'biological pollution'
People are to blame, a scientist in Boca Raton says.
[August 24, 2008]
The most disruptive and destructive species to Florida freshwater systems walks on two legs, according to Paul L. Shafland.
People are the root cause for so many nonnative fish flourishing in Florida water.
Shafland has just published, with Kelly B. Gestring and Murray S. Stanford, "Florida's Exotic Freshwater Fishes -- 2007," a study examining the exotic fish swimming in Florida waters.
Shafland is a senior scientist with the Florida Fish and Wildlife Conservation Commission's Non-Native Fish Laboratory in Boca Raton.
According to the study, 23 exotic fish species are reproducing and established in Florida. An additional nine species are reproducing, but it's too early to determine if they are establishing themselves permanently.
Two other species are reproducing but are confined and limited to specific water systems.
State biologists also have identified 21 other species described as "species of interest" that have been found in Florida's fresh waters but haven't yet shown signs of reproducing.
"The potential of these fishes to detrimentally affect native species has been a major concern of the (state wildlife commission) for more than 40 years," the study said.
The commission's "objective is to eliminate all illegally introduced fishes wherever and whenever practical; however, when this is impracticable, its goal is to assess the ecological and socioeconomic ramifications of these species, and to develop management strategies that minimize their deleterious effects."
Gulf of Mexico and other marine waters may not be safe from unwanted species.
The Florida Fish and Wildlife Research Institute in Tampa recently reported the catch of a marine red lionfish, which is native to the western Pacific Ocean, in Gulf of Mexico waters off Pinellas County.
The research describes red lionfish as venomous and able to inject venom, which may cause severe local pain, numbness, paralysis, respiratory illness and, in rare cases, death.
Serious wounds have resulted from the careless handling of recently dead specimens. Marine institute researchers warn that lionfish should be treated with care at all times.
Habitat friendly
Florida researchers believe many exotic species entered Florida by aquarium owners who grew tired of caring for their fish or those who found their fish tanks overrun because of reproducing cichlids or other aquarium fish species.
Some species, such as the flathead catfish, may have been deliberately stocked by sport anglers. The flathead catfish -- which is native to the Mississippi drainage system and other Midwest water systems 00 turned up in Georgia waters in the 1970s. The species filtered its way south into Florida Panhandle rivers and water bodies.
Historically, too, tropical fish farms throughout Florida weren't regulated as well as they are today and often saw fish escape from ponds and tanks after hurricanes, and then find their way into canals and other water systems.
"Ninety percent of exotics (released) don't survive," Shefland said. But the remaining 10 percent do well in Florida's aquatic habitats, especially canals.
The state's various canal systems, dug for drainage and storm water, provide excellent habitats for tropical and semi-tropical fish species.
"You couldn't design a more acceptable (habitat for exotics) if you tried," Shafland said of the canal systems. Often the canal cut into the aquifer; which keeps the deeper waters of the canal warm enough to allow exotic species to survive.
Exotic species "fill a niche," Shafland said. However, he also called nonnative species "biological pollution" and equates dumping aquarium and other exotic fish into waterways to someone throwing fast food wrappers and garbage out a car window.
He also believes the exotics fare well in habitats that have been disturbed by human engineering and intervention -- such as digging canals to drain the Everglades.
Many of the state's native fish species -- such as the largemouth bass, bluegills and other sunfish -- are at the southern reaches of their range Shafland said, and that can lead to stress.
Exotic species flourished so well in fresh waters of Miami-Dade, Broward and Palm Beach counties that state wildlife officials decided to fight fire with fire.
In 1984 to 1986, the state deliberately stocked butterfly peacock bass, a game fish species native to the Amazon River drainage basin, into coastal canals.
The butterfly peacock bass now is established in South Florida waters, is a recognized game fish and has generated a $10 million sport-fishing industry in Miami-Dade, Broward and Palm Beach counties.
The world record for butterfly peacock bass is 12.6 pounds and was caught in Venezuela. The Florida record is 9.08 pounds. Since the initial stockings, the state has set a daily limit of two fish with only one allowed to be longer than 17 inches.
And the peacock bass has done its job to reduce the quantity of exotic forage fish in canals.
A general biological rule is that the ratio of forage fish to predator or game fish should be 3 to 6 pounds of forage fish to every 1 pound of game fish, Shafland said. The ratio in South Florida waters reached more than 12 pounds of spotted tilapias and other species before the peacock bass were introduced.
Since the introduction of the peacock bass, Shafland said, the canals appear to have seen a 40 percent reduction of the forage fish.
The peacock bass also doesn't appear to be lessening the native largemouth bass population.
Where a largemouth bass feeds on fish, crawfish and other aquatic species, the peacock bass' diet is strictly fish. The two species, Shafland said, also spawn at different times.
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