State wildlife officials are circling Texas seeking public views on banning the controversial but 6-decade-old use of gasoline fumes to drive hated rattlesnakes out of cracks, crevices and sinkholes, and into the clutches of hunters who enter them at rattler roundup contests with top prizes of $500 or sell them to dealers at $10 a pound or more.Nowhere is the proposed rule change as emotive a topic than in Sweetwater, 192 miles west of Fort Worth, a town of 10,600 that swells to 35,000 during the “world’s largest rattlesnake roundup” each March. A ban could cripple the festival, predict officials, who say 80 percent of the snakes brought in are caught by gassing.Not only is it the annual event in Sweetwater, the roundup raises as much as $55,000 that local Jaycees recycle as donations to a hospice and the Fire Department. The funds also cover a dinner for the child advocacy center, Thanksgiving meals for more than 600 people, anonymous Christmas gifts to needy families and bicycles to eight students with perfect attendance, Jaycee David Sager said.Unlike Fort Worth, where just three people spoke and all fervently in favor of a ban, the Texas Parks and Wildlife Department is expected to get a larger, far different reception in Sweetwater. “Last time I heard, rattlesnakes were not an endangered species,” Sweetwater Mayor Greg Wortham thundered over the phone.Like many in his town, Wortham sees gassing as the most effective way to catch a snake, whose bite can cause fatal swelling in calves and threaten the lives of humans. “Suddenly there’s a problem,” he went on. “My father almost died from a rattlesnake bite. But to hear these people, we’ve got to save them. People in Austin don’t understand. We’ve got to protect our families, ranchers, people who work in oil fields, on wind turbine sites.”The wholesale hunting, driven by big cash awards and payments, helps keep the snake population in check, the mayor insisted.But as host of the roundup, Sweetwater has gotten a bumper crop of angry letters and online comments from out-of-state conservationists, mainly of the Yankee variety, for allegedly abusing the Western diamondback rattlesnake, he said. “If they love them so much, I might just start a rattlesnake relocation program and send a FedEx box full of their favorite snakes to Massachusetts.”So culturally ingrained is rattler hatred in parts of West Texas that nothing wildlife officials may say would convince Wortham and his constituents.John Davis, the department’s wildlife diversity program director, said the proposed rule change resulted from a petition received in March 2013. “In responding to that, we felt that the data indicated it was time to propose a rule to address the threats this means of [catching] presents,” he said.Citing a number of studies, Davis told the Fort Worth audience not only that gas fumes kill as many as half the snakes that don’t escape, but also that the tactic is indiscriminant. Moreover, the vapors can kill a host of other animals and insects, some 26 on the federal endangered list, like the nearly blind spiderlike Colkendolpher Cave harvestman, not to mention fouling habitats for other species.“We should not allow this anywhere in the country,” said herpetologist Kristen Wiley, curator of the Kentucky Reptile Zoo & Venom Sales of Slade, Ky., a nonprofit producer of venom for canine and equine snakebite vaccine.Nor would she mind if the proposed ban strangles rattlesnake roundups.Like the Humane Society of the United State, Wiley contends that the roundups abuse animals. “I’ve seen a roundup picture of a live snake with its mouth sewn shut,” she said, noting that snakes can be bagged with scores of others and, disoriented, dropped to the ground at a roundup from a height of 4 or 5 feet.“They are raising money by torturing animals.”Critics of gassing assert that rattlers can still be caught, and humanely, by going when the weather is right so the snakes can be plucked up as they sun themselves outside their dens.Sager, 63, who has hunted snakes since childhood, says one would be lucky finding four or five snakes this way after walking miles, whereas pumping gas fumes would quickly net as many as 50. Nonetheless, a Fort Worth snake fancier named Clint King photographed about a score of diamondbacks laying in a pile outside a crevice with more crawling out.One of the people who can see both sides of the issue is Clark E. Adams, a professor of wildlife and fisheries sciences at Texas A&M University, and a co-author of a book on Texas roundups. Hunters know that other species are affected by gassing, “because they see them running out” of the caves, Adams said in a telephone interview. “But it’s not an issue to most of them,” he went on. “What it comes down to fundamentally is that you have to get rid of the snakes on your ranch. One female had 30 ovaries, meaning 30 more snakes. They have to be removed in one shape or form for the safety of humans.” And gassing, he said, “is still the most effective way to get them out of the den.”Ken Darnell, a critic of the parks and wildlife proposed ban who is an Alabama patent attorney and snake venom buyer, maintains that the department already has hurt his industry by requiring permits and new reporting requirements, leading to the drop in hunters from 4,000 to about 800 in the past decade. The recent death of a major buyer in the South Texas town of Freer closed a sprawling operation where the snakes were largely caught in the open without gassing, he said.While he personally opposes the use of gasoline fumes, Darnell asserted that a ban could lead to a critical shortage of antivenin for snakebite victims.Davis dismissed the prediction in a Jan. 9 email, citing a statement from British-owned, Utah-based BTG-Protherics, the major antivenin manufacturer, which said it collects its venom in house. “BTG has all its own Crotaline (subfamily, including diamondbacks) specimens. Venom is produced under strict laboratory protocols and outside venom sources cannot be used.” Well, not exactly. Richard Straight, a former university scientist who is director of the Utah operation, clarified Friday that it has produced “most” of its own venom and became self-sufficient for Western diamondbacks only with the 2014 production. Straight said it will continue to buy Eastern diamondback venom from Biotoxins of St. Cloud., Fla., because the climate in the southeast is more suitable for the species than Utah. Darnell disputes Straight’s assertions. He said his venom, much of it collected in Texas, is pooled with that from Biotoxins and another Florida producer, then Biotoxins ships it to BGT and handles the marketing. If BGT is now self-sufficient, he asserted, it’s only because it stockpiled 5 kilograms of venom over the past two, three years. “Straight will have to admit it under oath if this ever goes to court,” said the 69-year-old attorney-venom purveyor, who said last week that he had received a $202,000 check for three months of shipments.