© Scott Sonner/Associated PressJoggers and dog-walkers make their way around the Sparks Marina, Wednesday Jan. 15, 2014 in Sparks, Nev. State wildlife biologists are trying to figure out what caused the kill-off the man-made lake's entire stocked fishery an estimated 100,000 trout, bass and catfish. The 77-acre marina sits in an old rock quarry along U.S. Interstate 80 just east of Reno.
An estimated 100,000 trout, bass and catfish have died over the past month in the Sparks Marina along U.S. Interstate 80 east of Reno, apparently the result of a dramatic, unexplained drop in dissolved oxygen levels, Nevada Department of Wildlife spokesman Chris Healy said Wednesday.
Scientists say a bitter cold snap could have caused oxygen-poor waters to rise from the old rock quarry's bottom to the surface, but they don't understand what sparked the massive die-off.
Fish biologists confirmed low oxygen levels caused the death of an estimated 3,000 fish in one corner of the lake in mid-December, but Healy said they thought at the time that the event was localized and of limited impact. Since then, they've been unable to detect any live fish in the 77-acre lake. Numerous dead fish have been removed from the lake's shoreline, and Healy said it's likely the rest sank to the bottom.
"The 100,000 dead fish figure is something that is probably a pretty conservative guess," said Healy, who estimates they've stocked close to 1 million adult fish in the lake since they started in 1998.
"We don't know if any small fish have survived, but for all intents and purposes, the fishery doesn't exist anymore," he told The Associated Press.
