State Game and Fish Department officials say toxic algae bloom was responsible for the deaths of more than 100 elks discovered north of Las Vegas in August.
“Based on circumstantial evidence, the most logical explanation for the elk deaths is that on their way back to the forest after feeding in the grassland, the elk drank water from a trough containing toxins created by blue-green algae or cyanobacteria,” said Kerry Mower, the agency’s wildlife disease specialist.
The carcasses were discovered within a half-to three-quarter- mile area of Game Management Unit 46. They appeared to have died within a 24-hour period.
Game and Fish biologists initially suspected that a virus — Epizootic hemorrhagic disease — might have been responsible for the deaths. They collected tissue samples from the dead elk and water samples from privately owned land north of Las Vegas.
Those samples were sent to laboratories across the country for analysis. A lab found anabaena, a naturally occurring blue-green algae that produces the deadly neurotoxin, anatoxin-a, in a water sample, according to a Game and Fish news release.
“This potent neurotoxin can cause illness and death within four to 12 hours if ingested,” the release states.
According to Game and Fish, the elk showed signs of having struggled on the ground, symptoms that the agency says are consistent with poisoning from a neurotoxin.
“Although some types of microscopic blue-green algae produce toxins, they seldom cause serious problems,” the release states. “During warm weather the algae can reproduce quickly in standing water, creating a bloom that releases deadly neurotoxins into the water.”
The release states that the conditions resulting in the elk deaths existed only a short period.
Game and Fish officials say they investigated a wide variety of possible causes for the deaths in addition to the blue-green algae. Among the other possibilities they looked into were anthrax, botulism, lightning strike, poaching, poisonous plants, malicious poisoning, toxic levels of sulfate and nitrate and the possibility of an industrial or agricultural accident.
All of those things, along with epizootic hemorrhagic disease, were ruled out.
“No one has reported dead livestock or wildlife in the area since August,” the release states. “Hunters should not harvest animals that exhibit unusual behavior or appear sick, and should report anything unusual to the department’s toll-free information line: 888-248-6866.