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Devil's Hole Pupfish Breeding Not Going Well


Devapupfish_copy_2     This is not good news.
    A determined bid to save the waning population of Devil's Hole pupfish from extinction has resulted in the deaths of not only 10 pupfish fry but also of two of the adult males counted on to become the patriarchs of a captive-bred pupfish population.
    Now fisheries experts with the National Park Service and the U.S. Fish and Wildlife Service are plotting their next move, one that could involve plucking two more males from the existing population for the breeding program.
    It was just three weeks ago when 10 pupfish fry and four adults -- two males from Devil's Hole and two females from the Hoover Dam pupfish refugia -- were scooped up with expectations that they could be bred in captivity.

    John Wullschleger, a fisheries biologist with the National Park Service, tells me a decision could be made as soon as this afternoon to move two males from the Hoover Dam refugia into the captive-breeding effort at the Mandalay Bay Casino's Shark's Reef aquarium in Las Vegas.
    Officials responsible for making that call are understandably nervous. When the 10 Devil's Hole fry were moved three weeks ago and sent to the Willow Beach National Fish Hatchery for rearing, they all died within 24 hours.
     Then, an accident at Shark's Reef apparently altered the pH of the water in the tank where the four adults were being held, and that nearly killed them. While they rebounded, and one male even managed to spawn, he died after spawning and the other male died a bit later. The two females are still alive.
    Wullschleger says they haven't figured out exactly what caused the males' deaths. In fact, he says they might have been natural as the males could have been near the end of their 10-to-12 month life span.
    So where do things stand now? Well, while biologists haven't recounted the Devil's Hole population since mid-April when they spotted 38 adults, the pupfish population at the Hoover Dam refugia has dwindled to 22 individuals as of last week, down from 29 in mid-April.
    Wullschleger is optimistic that numbers will increase somewhat during the summer months, as the latest counts have focused on adults and larval-stage individuals could be on their way to maturing into adults.
    Still, with only about 60 known adults left in the Devil's Hole population, the future looks pretty bleak for this little fish.

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