Perhaps more than the people of any other state, Florida residents are attracted to the collection of bizarre pets. Tropical fish shops abound; a house without an aquarium is not a home. And Florida has seen turned loose in its wilds more exotic beasts, birds and reptiles than any state except Hawaii. The results have not always been happy. Just as Hawaii learned from its experience with the mongoose, and Australia learned from rabbits, so Florida is learning from the red-whiskered bulbul, the poisonous giant toad and the South American caiman that a wide-open immigration policy can be dangerous, especially in an area and climate where all things seem to flourish. Or is the state really learning? Gloomy biologists, worrying about the effects of strange animals intruding on the stamping ground of native species, think there ought to be a law against it all, but find little public outcry for one. As of the moment, the pet shop lobby has the situation well in hand. But now game fishermen—and fishing is one of Florida's chief industries—are beginning to worry. The native black bass (Florida's largemouths are the biggest to be found in any state) is facing competition from the African cichlid and the peacock cichlid, which are something on the order of American sunfishes. But an even greater threat, perhaps the worst of all, now looms.
A year ago last March a boy fishing with worms in a canal near Palm Beach caught a very strange fish. It breathed air and was capable of walking, after a fashion, on land. Otherwise it looked like a catfish, whiskers and all, except that it had white skin and pink eyes. There are some 2,000 species of catfish scattered around the world and it took a little doing to pin this one down to the point of positive identification. Bob Goodrick, fisheries biologist of the Florida Game and Fresh Water Fish Commission, studied the fish, and Dr. Walter R. Courtenay Jr., ichthyologist and assistant professor of zoology at Florida Atlantic University, dissected it. Eventually the curious thing wound up at the Academy of Natural Sciences, Philadelphia, which identified it as Clarias batrachus, or, as we say, walking catfish. Furthermore, it was an albino of the species, which accounted for the white skin and pink eyes. A little research disclosed that an ordinary, run-of-the-mill walking catfish is not fantastic enough for the keepers of home aquariums in Florida, and so thousands of albinos—the first of them from Thailand, which also supplies us with Siamese fighting fish—were imported by the pet and fish shopkeepers. Catfish were going like hot fish cakes at 69¢ apiece when newspapers began reporting that they were a danger to the ecology of Florida. Then, so perverse is the human condition, the price jumped to 89¢.
Many kinds of catfish have a way of being weird. There is a European variety (Silurus glanis) which is said to reach a length of 10 feet and weigh 400 pounds. It does not walk, but catfish of the Andes have been known to climb precipices. And walking is not confined to the Southeast Asiatic type found in Florida. An African catfish, which grows to a weight of 50 or 60 pounds, also strolls about when the spirit moves it. Then—and this has to be the absolute end in nonconformity—there is a Nile catfish that is white on its back and black on its belly. The reason: it swims upside down.
The catfish found in Florida may be said only out of courtesy to "walk." It moves more like a man crawling on his elbows. They have strong pectoral fins with spines on them which serve as anchors, and on these they more or less elbow their way forward, assisting their progress by sculling with their tails. On very dry land their skin may be scraped badly but it heals in two or three weeks. Sometimes, in walking under adverse conditions, they lose their whiskers (barbels) entirely but these are regenerated in a week, says Dr. Courtenay.
November 11, 1968
Once alerted to the dangers implicit in the presence of a walking catfish on Florida soil, the biologists began studying the beast with a kind of nervous intensity. They came to conclusions that are not encouraging. Goodrick and a colleague, Vernon E. Ogilvie, found that "the usual barriers [salt water, control structures, levees, etc.] which confine or control the movements of freshwater fishes do not apply to the family Clariidae. A fish with the ability and inclination to leave the water and 'walk' around is, to the best of our knowledge, unmanageable," they concluded.
"The individual or individuals responsible for introducing the Clarias catfish may have done the people of Florida a great disservice," they said. "It is quite possible that the Clarias may have a more detrimental effect on the ecology of Florida than any other group of fishes, including the piranhas."
Piranhas, whose importation is now-prohibited though pet shops have sold thousands in the past, have been reported present in the Everglades, but this has not been confirmed. They are, of course, those voracious South American devils, more deadly than sharks, a school of which can strip an entire animal, including man, down to a skeleton in a matter of minutes.
Well, a walking catfish can scare the hell out of a piranha. The catfish are extremely aggressive, though it is not true, as an excited lady reported, that one of them attacked her dog. Still, a specimen 13 inches long did kill another of equal size in a 70-gallon tank and so terrorized the other fish, both exotic and native, that, as Ogilvie and Goodrick reported, the fish "gave the Clarias a wide berth, the piranha being no exception."
The walking catfish is a most powerful jumper, capable of leaping four feet out of the water, which would be considered rather more than exceptional for a trout or salmon, and on land they are able to move at a rate of 20 to 30 feet a minute. They have not actually been observed moving overland for as long as a minute, since they are then hunting for such food as snails and pause from time to time to sniff the air or something, but that is their rate of speed. In addition to snails they are fond of freshwater shrimp, crayfish, frogs, tadpoles and, most importantly, small game fish—like baby bass.
The walking catfish "are so strong and slippery," Ogilvie and Goodrick reported, "that it is nearly impossible to handle them." Few would want to. Some have tried their flesh (the preference is for frying) and, with something less than enthusiasm, pronounced it edible, but skinning them is an ugly and difficult task and the odor can be offensive.
They grow to a length of 18 or 20 inches and seem to breed at an extraordinary rate. Of those collected by the Game and Fresh Water biologists up to mid-October, the ratio of young to adults was about 75 to 1. The biologists collected a total of 4,000, of which about 1,500 were from dealers, the rest found in the wild.
What enables the catfish to breathe indefinitely on land—one has been found half a mile from the nearest water—is a pair of "accessory breathing organs" which cannot quite be called lungs but make it possible for the species to live in water almost deprived of oxygen. They, and especially the albinos, are extremely sensitive to sunlight, and they come ashore in search of food chiefly at night. As they breed, however, the albino strain is diminishing and the fish is reverting to its natural coloration, which is gray on the back, with tiny white spots, and the customary white belly. If caught out during the day in the dry season, a mud hole left by a drying canal or pond will protect them. They just bury themselves in the mud.
All the fuss started when a dealer in exotic fishes dumped some catfish into a rearing pond and neglected to build a fence around it. The catfish had no trouble escaping, and pretty soon they were being found in quantity in both Palm Beach and Broward counties. Since Florida has a widespread network of interconnecting canals, almost all of them with access to lakes and streams, the presumption must be that one day the whole of the state will be infested.
Present opinion among biologists is that nothing much can be done about it since, as Dr. Courtenay observes, even rotenone, a standard poison for killing fish, does not work too well on the catfish. Some succumb, but others—once they get a whiff of the stuff—climb out of the water and seek a healthier environment, leaving behind a floating mass of dead native fish.
The ultimate effect of the catfish on the native game fish population is in a merely speculative stage now. It is remotely conceivable that a predator that can control them may turn up in time.
Goodrick would like to run a test of the effect on natives by introducing catfish into a fenced-in pond already stocked with native species. After a time the number of natives would be counted. An appreciable decline would be ominous. To affect the native population the catfish would not necessarily have to eat the young, though he has been known to do that too. A body of water of given size can support only just so much life because it can supply only just so much food and breeding facilities. Introducing an aggressive exotic into the environment, especially so prodigious a breeder as the catfish seems to be, adds to the competition for food and Lebensraum. The catfish would have a rather special advantage, too, since he can leave a depleted body of water and feed off the land while looking for a better hole.
The walking catfish is not the only import to give Florida headaches. The too-familiar water hyacinth, a Venezuela variety with very pretty blossoms, turned out to be a lovely nuisance, choking canals, streams and lakes and costing the state millions of dollars just to keep it under some kind of control. One hyacinth can become 65,000 in a single year, during which the state will have spent $1 million trying to clear out at least a reasonable quantity. In desperation sea cows, which eat enormous quantities of vegetation, were introduced a few years ago, but water hyacinths seem to spread faster than sea cows can eat them.
During the 1950s the Mediterranean fruit fly invaded Florida and attacked the citrus crop. To eradicate it cost $11 million—and in 1965 it was replaced by the Caribbean fruit fly. The battle against that one is still going on. While the state's fruit farmers wield their fly swatters, or whatever, they are worrying about another immigrant, the red-whiskered bulbul, an Asiatic bird that dearly loves oranges and lemons. Like so many other exotics, including the walking catfish, the bulbul became a problem soon after it escaped: 10 years ago a hurricane blew down a huge cage on a rare bird farm and now the bulbul is not so rare.
Then there is the giant South American toad (Bufo marinus), which is poisonous, as all toads are to some degree, but in this case especially so. With legs stretched out fore and aft, these toads can attain a length of 30 inches or more, and they have poison sacs of considerable size in their necks.
Introduced and turned loose deliberately in 1958, the idea was that Bufo would eat harmful insects in greater quantities than the little native toads, and thus aid agriculture. This it has done faithfully, but it has begun to put down the native population by consuming their share of the food supply. And worst of all, it is a menace to dogs, hundreds of which have been killed by Bufo. It doesn't bite them, they bite it, and in doing so they puncture the poison sacs in the toad's neck.
(Will the person or persons who recently stole several hundred little South American frogs—Dendrobates tinctorious—from a tropical fish importer's stock please not release them? Colombian Indians dip hunting arrows in their poison.)
Another pet shop importation was the South American caiman, a member of the alligator family and a nasty one. A Florida alligator is a cuddlesome thing compared to a caiman, which grows to a length of six feet and is both aggressive and vicious. The pet shop people used to make a great thing out of selling native baby alligators to both tourists and residents. Then, because the Florida alligator was approaching extinction due to ecological factors and the depredation of poachers, the law forbade sale of the natives. The shopkeepers turned to the caiman as a piece of merchandise. It sold well because most people don't know the difference. But when it was discovered that caimans tend to bite off the hand that feeds them a lot of pet owners turned them loose to increase and multiply, which they did.
In a recent issue of The Florida Naturalist, published by the Florida Audubon Society, Dr. Wayne King, associate curator of reptiles of the New York Zoological Park, listed 62 exotic vertebrate species that have made a good thing out of moving to Florida. Among them were 15 mammals (including rhesus monkeys, coyotes and ocelots); 12 birds (budgerigars, starlings, Egyptian geese); 19 reptiles (tokay gecko, rhinoceros iguana, Texas horned lizard); three amphibians (giant toad, greenhouse frog, Cuban tree frog); and 13 fish (gar pike, top minnow, black acara and armored catfish). No mention was made in the list of the walking catfish, perhaps because it has not yet been established scientifically that he will stick around.
All the others are well-entrenched, though, and leaving their mark on the ecology. The imported scarlet ibis, for instance, is mating with the native white ibis, and that means the resulting hybrid, the scarlet-white ibis, will not be able to reproduce itself any more than a mule can. Nevertheless the Florida Game and Fresh Water Commission has put the scarlet ibis on its protected list. It's so pretty.
Even imported plants have been found to be a menace. The cajeput tree, originally found only in New Guinea and Australia, is quite spectacular, growing to a height of 100 feet or more, and so in 1912 some were brought over the seas and planted in Florida. Now they are spreading through the Everglades and, as King points out, "destroying suitable habitat for many native animals.
"Because it is not restricted to roadside canals and ponds," King observes, "it will be harder to control than even the water hyacinth."
Because they are so isolated, probably, King did not bother to list the exotic animals on St. Vincent Island, off Apalachicola, where African zebra, elands, giant African antelope, German boar and Sambar bucks may be observed, provided you can get approval for a visit from the U.S. Fish and Wildlife Service, which worries about boars attacking tourists. The whole thing is the creation of a patent medicine millionaire, Dr Ray V. Pierce, who bought the island early in the century and stocked it with animals of his choice. Fish and Wildlife owns it now.
Nor did King mention the boa constrictors and anacondas that have been reported in the Everglades.
Botanists, zoologists, ecologists and plain sportsmen are extremely worried about the effects of exotics on Florida's wildlife but, in fact, this worry may turn out to be academic. The greatest exotic of them all, civilized man, is doing vastly more damage to Florida than the walking catfish, the red-whiskered bulbul or the cajeput tree. A few years ago the U.S. Department of Agriculture predicted that within 35 years the soil of Florida from Lake Okeechobee south will have been oxidized into limestone. Even before then there had been predictions that the area would rather soon be converted into a salt desert. That gives Florida until around the year 2000 A.D. to do something about it, if anything can be done.
"I don't think we'll miss that date by much," says Larry Shanks, project leader for the River Basins Study of the Florida Game and Fresh Water Fish Commission, "if we keep getting more people down here."
The trouble with people is that they use so much water, personally and industrially. So long as the state's flat freshwater marshes are let alone they retain half-decayed organic material in which plants, animals and fish can survive and reproduce. But when such an area is drained, the muck dries and oxidizes. The final product is useless limestone. So long as civilized man uses the water for drinking, for agricultural irrigation, for carrying off industrial waste, for salinity control and for sewage disposal, there is little hope that the process can be reversed. For the past several years Miami has been rationing water, but the water table continues to fall.
All the continuing deterioration of this prolific land comes directly or indirectly from trying to fulfill the needs and wants of people. As more people and industries come in (and the population is rising fast) more water must be pumped up from the underground rivers. There have always been, on a modest cyclical scale, fairly gentle rises and falls in Florida's water reserves, but in recent years the contrast between floods and droughts has been dangerously severe. Because the fresh water from underground rivers is constantly being pumped up for industrial, agricultural and sewage disposal use, the loss of pressure eventually may allow salt water to pour in. Then Florida, or a big chunk of that pleasant peninsula, is finished.
Early in this decade, when drought in the Everglades was critical, the U.S. Army Corps of Engineers was pressured into doing something that would supposedly guarantee the great national park a consistently adequate supply of water. The Corps borrowed a computer at Cape Canaveral and concluded that by about the year 2012 extraordinarily drastic measures would have to be used to produce water. The natural supply would be gone. (Florida's Flood Control department computes this date to be closer to 2000.)
So far nothing that promises to be effective has been done, and Shanks thinks that all measures will be futile unless the number of people and industries allowed to settle in southern Florida is limited by strictly enforced zoning laws. The public is aroused to some extent (the Audubon Society, women's garden clubs, the League of Women Voters) but not enough. Industries still are clamoring to buy more land. Housing developments are cluttering the landscape with houses on small lots. Businessmen recently asked to drain part of a conservation area in the Everglades to build the world's largest airport.
Maybe Ponce de León should of stood in bed and maybe the walking catfish, if it had studied the situation, would have elected to stay in Thailand.