Gophers In Peril
By Michael James
The Gopher Tortoise (gopherus polyphemus) - the Seminoles' stubby legged symbol of resilience and survival - and, traditionally, something to eat - has come under attack from an invisible enemy. Gophers are succumbing to a contagious respiratory disease that could bring the animal to the brink of extinction. Known as URTD (Upper Respiratory Tract Disease) the disease is extremely contagious and nearly always fatal.
According to a recent Associated Press article, biologist Joan Berish with the Florida Fish and Wildlife Conservation Commission (formerly known as the Game and Fish Commission) is trying to get to the bottom of a problem that was first recognized and documented at Sanibel Island, Fla. in 1991. More than 80 percent of the animals tested on Sanibel were seropositive for antibodies against the bacteria known as M. agassizii. Since the discovery of M. agassizii in Florida, it has been found throughout much of the tortoise's range in the southeastern U.S.
Berish's work is focused on trying to determine how many tortoises may be infected, how fast the disease is spreading, and how many tortoises are dying. Berish's research is concentrated near the Jacksonville area at the Cecil Field Naval Air Station. "We just don't know," said Mrs. Berish, who has been studying the animals for 20 years. "These animals don't unlock their secrets quickly."
For more than a decade, the Seminole Tribe of Florida has provided a safe haven for gophers on several acres of wilderness set aside at Billie Swamp Safari. When land is developed elsewhere in the state, developers are required by law to safely translocate gophers found on the site. The Tribe contracts with the developer to bring the gophers to Big Cypress, says the Seminoles' Chief Legal Counsel Jim Shore: "It's an ongoing program that is administered on a case-by-case basis. But we haven't had anyone contact us about gophers in a long time."
No evidence of disease has been found, or is suspected, on the Seminole lands and Commission biologists have no plans to investigate anytime soon. People who eat gophers do not have to worry - the disease will not affect humans in any way.
Last year, 60 tortoises were fitted with radio transmitters and for the last several months, Berish has been trapping them at four locations in north Florida. Several weeks ago, Berish and research assistant Lori Wendland returned to Cecil Field to set traps for the colony of tortoises sunk into the ground near the burrows of the colony that lives near the base runway. The traps are simple devices consisting of five-gallon buckets sunk into the ground near the gopher=s burrow. Upon inspection they found gopher #27 in the first trap. The scientists took blood and mucus samples.
Last year the animal known as #27 tested negative. This year she doesn=t have a runny nose or swollen eyelids...the classic symptoms of the deadly infection. Other symptoms may include an inflamed respiratory tract and wheezing. An infected tortoise eventually starves to death because it cannot find food to eat.
Although there is a test for the disease there is no vaccination and no known cure and scientists warn that some tortoises can appear fine while still carrying the disease. Some tortoises may test positive without showing any of the classic symptoms. One way URTD is spread between populations is by the introduction of a diseased tortoise into a healthy colony. This fact becomes particularly important when weighed against the 1979 listing by the Florida Game & Freshwater Fish Commission's listing of the gopher as a "species of special concern."
According to Berish, since the listing there have been 450 permitted relocations that have involved over 8,000 tortoises. Particular attention has been focused on the dynamics and persistence of both natural and relocated populations. The potential for introducing diseased animals into an otherwise healthy colony is very likely under the current relocation policy.
According to one significant report, ACapturing and transporting of tortoises during relocation, restocking and repatriation effort also may be a significant factor for the presence of URTD in certain populations. For instance, the release onto Sanibel Island of gopher tortoises originating in northern Florida and southern Georgia following tortoise races has been documented. Many of these tortoises were kept under very poor husbandry conditions that would have allowed transmission of various pathogens.@ (Dietlein & Smith, 1979)
Of the 40 species of tortoises, URTD and its causative agent has been identified in desert tortoises, gopher tortoises, leopard tortoises, Indian star tortoises, Asian tortoises, spur thighed tortoises and box turtles. Presently it is not known whether or not URTD was accidentally brought to the U.S. from somewhere else or if it is a natural illness that is currently cycling.
The disease is known to occur in wild gopher tortoises in Florida, and in wild desert tortoises in California, Nevada, Utah, Arizona and Testudo graeca in France. The disease is primarily seen in adult tortoises in the wild but under experimental conditions, all age groups are susceptible.
Since the implication of Mycoplasma agassizi a second, genetically distinct mycoplasma has also been isolated from tortoises in both desert tortoises and those form areas on the Florida-Georgia border. The second mycoplasma has caused URTD only in the Florida/Georgia species only under controlled laboratory conditions.
Mycoplasma's are tiny bacteria, which lack a cell wall. In humans, M. pneumonia is the agent, which causes "walking pneumonia."