DAMN-BUSIA
THE PAINFUL STORY OF GAMBUSIA AFFINIS / HOLBROOKI
by Robert Rice
President of the Native Fish Conservancy / www.nativefish.org
Let me begin this article by saying a bit about myself. I have been an avid fisherman, aquarist and conservationist most of my life. I have written about fishes wherever I've found them. I have fishes and collected in Canada, Mexico, Panama, Haiti and numerous other places in between. My passion for conservation is my primary motivation to write for trade publications. I have always strived for one thing in my writings. I strive to be an advocate for Native Fish Conservation. My fish room is a mix of sunfish, killies, and shiners with an oddball or two thrown in. It is however a mix of my local native fish.
People often ask me what is a native fish? The term Native Fish is a generic term for any fish that comes from a particular watershed. For example, the Longear Sunfish is a loved native where I live but an unwelcome invader in Germany, where populations have become established to the detriment of the local German fishes. Thus every fish is a native somewhere. I like to look at any particular local flora and fauna like a beautiful painting by a master. Every time we try to "improve" it with introductions, we change it, usually for the worse. We are in effect putting a moustache on the Mona Lisa. I for one find that a bit sad. Don't feel put off if I speak of one og your favorite fishes as an exotic. The term exotic fish simply means that the fish was placed into a waterway outside it's natural range by someone. So no matter where you live you can be a native fish nut!
I believe that, as aquarists, we can and should keep conservation in our hearts as we enjoy our hobby. Simple things, like buying captive reared fishes, never releasing a once loved pet and keeping an eye out for the animals we share our world with are little things that make a big difference. That kind of tells you where I'm coming from. I am not a hate monger or some anti-pet industry nut. I love our waterways and I enjoy them every chance I get; sometimes I walk them. occasionally I collect them. They are not ever too far from my mind, heart or fish room. I hope that you, the reader, keep that in mind as I discuss the Gambusia problem with you.
You see, Gambusia is a problem, a major problem, all over the world. The many unique types of Desert Pupfish of the Southwestern United States have been negatively impacted due to Gambusia. In Australia, Gambusia have implicated in the decline of the species of Ambassis, Chlamydogobius, Craterocephalus, Galaxias, Melanotaenia, Retropinna and Scaturiginichthys, as well as other native species.
I have watched one small spring after another in western and southwestern locations lose their diversity one tiny bit at a time as the Gambusia gain a foothold. Gambusia is like a virus, constantly dragging on our ecosystem. They drag it down until it becomes theirs. Thanks to the efforts of Gambusia some of my favorite spots from years past don't even merit a visit. Let me give you an idea of how widespread Gambusia is. On my lo0ng delayed second honeymoon to Panama, I took an afternoon dip around the small creeks on and near the airbase. I found, much to my dismay, Gambusia amongst the tetras and cichlids. Talk about a letdown; I travel 1,000's of miles, take a dip net and hope to catch some new, old friends south of the border and instead I find Gambusia. YUCK!!
What's a Gambusia? Gambusia affinis, and their close cousins Gambusia holbrooki are guppy-like livebearers of the Poeciliidae family. Gambusia are native to the southeastern Untied States and one could argue, are the most dangerous little fish on the planet. Gambusia are greenish brown on the back with a silvery white underside. They have large eyes positioned well forward on the body, a flattened dorsal surface and a broad tail for rapid acceleration. The females are much larger than the males. Although some people think they look like guppies, they are not. They are much more dangerous than guppies, which generally are not found living in the wild. Gambusia, on the other hand, lives almost anywhere. Lakes, streams, ponds, ditches, desert spring and even Arkansas trout hatcheries boast reproducing Gambusia populations.
How did they get spread so widely around the world? The Gambusia have been distributed worldwide by various government agencies to control mosquitoes. It was introduced into Australia in the 1920's, Asia in the 40's, and Europe somewhere in between. The Gambusia has been part of an ongoing and ecologically idiotic stocking campaign in most of the 50 US states. Do Gambusia control mosquitoes? This so-called mosquito fish has not been any more effective at controlling mosquitoes than endemic fish species. In fact, it's introduction has proved to be disastrous because mosquito larva form only a small part of it's diet, which includes ants, flies, aquatic beetles, rotifers, crustaceans, mollusks and the eggs and fry of native fish species. Recent studies have also shown that Gambusia have a preference for tadpoles over mosquito larva, and scientists are now worried that this is causing a serious decline in Amphibian populations around the world. For the sake of brevity I will not post all the studies out there, but a quick word search of Gambusia on google.com tells the story, and it's not pretty. Peterson's Field Guide to Freshwater Fishes by Lawrence M. Page and Brooks M. Burr simple states this about Gambusia: "Introductions of this species, often for mosquito control, have caused or contributed to the elimination of many populations of fishes with similar ecological requirements. Introductions into western drainages have been especially deleterious to the survival of certain rare fishes. pg. 237" That pretty much makes it plain. Gambusia are no more effective than local species in controlling mosquitoes. In spite of the overwhelming scientific data documenting their life habits, people still refer to Gambusia as the mosquito fish.
The situation today: The Gambusia now inhabits five continents. The Gambusia's spread has been fueled by various government agencies in a failed attempt to control mosquitoes. A job better done by local species! I hate to break the news to folks out there, but most fish when given the chance will eat mosquito larva. Some even specialize in it, like the killies, the rainbowfish and even Heterandria formosa, the pygmy livebearer; they all eat more mosquitoes than the much-vaunted Gambusia. The irony of all this is that we are paying our fisheries' agents to release exotic fish that is supposed to eat mosquitoes, but in fact prefers almost everything else much to the detriment to the local fishes and waterways that it invades. That does not sound like mosquito control to me. Diversity control perhaps, but certainly not mosquito control. The whole scenario is like releasing a 300 pound pig in your vegetable garden to control tomato worms. The cure is far worse than the disease. So do the worlds a favor, call the local fisheries folks and request no more Gambusia in any way shape or form. There are other options. As in "think local species"!