February 28, 2008
Texas Tries to Control Invasion of Exotic Snakes
Texas, like the rest of the nation, continues losing ground in its war against non-native, invasive species.
This month, giant salvinia, one of the most destructive and persistent of alien aquatic plants, was documented for the first time in three more Texas lakes -- Rayburn, Palestine and Brandy Branch.
Discovered in Texas in a single small pond in Houston only a decade ago, salvinia has spread to dozens of public and private waters across the eastern third of the state.
Able to grow so quickly and densely that it smothers the life from the water it covers and seemingly impossible to eradicate, giant salvinia is just one of the most recent invaders to inflict severe damage on Texas' ecosystems and the plants and animals that depend upon them.
The list of non-native species that have found their way into Texas, thrived and wrecked havoc on our natural resources and wallets is soberingly long.
Fire ants. Feral hogs. Chinese tallow. McCartney rose. Water hyacinth. Salt cedar. Hydrilla. Grass carp. Nutria. Formosan termites. Those are some of the big ones.
How much environmental and economic damage do alien-invasive species do in this country?
About $120 billion a year, according to a 2004 study by the College of Agriculture and Life Sciences at Cornell University. That's three times as much as ExxonMobil's $40 billion in profits this past year. It's seven times more than Microsoft's annual profits. It's a lot of money.
In Texas, fire ants' annual damage to wildlife, livestock and public health is estimated at $300 million. Experts estimate damage to Texas agriculture by feral hogs at $52 million a year.
But the most sobering destruction caused by invasive species is the damage done to the wildlife, fisheries and ecosystems they invade.
Fire ants are directly responsible for the staggering decline in Texas' horned-lizard numbers, the near vanishing of some native ant species and certainly a factor in the decline of some other wildlife.
Invasive plants such as phragmites and salvinia and Chinese tallow take over landscapes and waters, shoving out native plants, corrupting whole ecosystems and dooming many species of native plants and animals.
In Texas, salt cedar sucks so much water that, often, adjacent springs and creeks stop flowing or the waterways' salinity increases so much it is uninhabitable by native species.
The negative impact of non-native species on native plants, animals and fish is as pervasive as it is hard to exaggerate. Competition, predation or other impacts of invasive species are considered the primary risk factors facing about 400 of the approximately 1,000 species listed as threatened or endangered under this country's Endangered Species Act, according to a 1998 study.
Faced with the onslaught of invasive species and spending billions fighting them, state and federal governments have begun trying to address the root causes of the problem -- humans transporting and introducing non-native species.
Texas has imposed a prohibition on possessing dozens of non-native species of plants, fish, animals -- a list that grows longer each year.
It's now a misdemeanor criminal violation in Texas for people to not remove from their boat trailers any non-native vegetation such as hydrilla, hyacinth and salvinia.
And beginning April 1, any person in Texas possessing or offering for sale any venomous snake not native to Texas or any of five species of non-native constrictors will have to obtain a permit from the state.
Acting on a mandate from the 2007 session of the Legislature, the Texas Parks and Wildlife Commission this past month adopted rules creating a "controlled exotic snake permit."
Under terms of the regulations, any person possessing or transporting a venomous snake not native to Texas, a green anaconda, or any of four species of python (African rock, Asiatic rock, reticulated, southern African) must buy an annual permit from TPWD.
Private owners of the regulated species will be required to annually purchase a $20 "recreational controlled exotic snake " permit.
Businesses selling snake species covered under the regulations would be required to hold a $60 annual "commercial exotic snake permit."
Penalties for not complying with the permit rules would be a Class C misdemeanor, punishable by a fine of $25-$500, said Major David Sinclair of Texas Parks and Wildlife Department's law enforcement division.
Texas hopes to avoid -- or at least defer -- seeing the problems Florida currently faces with its exploding "feral" population of large, non-native snakes.
Over the past decade, released or escaped pythons have established breeding populations in southern Florida.
Just in Everglades National Park, more than 400 Burmese (Asiatic) pythons, some 13-15 feet long, have been found and removed.
Florida makes owners of the large, non-native snakes pay a hefty price for the potentially damaging reptiles and has imposed a method of trying to track and punish owners of escaped or released big snakes.
As in Texas, anyone in Florida convicted of releasing one of the non-native snakes faces a heavy fine.
Sadly, the natural world is paying a much higher price from such irresponsible acts.