Hatchery officials still seeking cause of big trout kill

Scott Sonner

Monday, March 27, 2000 | 2:56 a.m.

RENO, Nev. - Federal fish managers began sterilizing a northern Nevada hatchery Monday, still baffled by what caused the bacterial outbreak that led to the death of thousands of cutthroat trout.

"We're still investigating how the disease got in the hatchery," said Randi Thompson, spokeswoman for the U.S. Fish and Wildlife Service.

Officials destroyed 350,000 young Lahontan cutthroat trout in February to try to stop the spread of disease at the Lahontan National Fish Hatchery south of Gardnerville.

Attempts to treat the fish with antibiotics failed and 63,000 more had to be killed two weeks ago - bringing the total to more than 500,000 in the past few months.

Hatchery workers destroyed the fish by suffocating them with an infusion of carbon dioxide pumped into the shallow water-holding tanks.

Biologists have struggled since November to treat the fish afflicted with Furunculosis, a bacteria found naturally in northern Nevada's watersheds.

It's most likely that either birds transported the bacteria or leaky pipes from the hatchery wells allowed it in, Thompson said Monday.

Extensive flooding along the Sierra Nevada's eastern front in 1997 uncovered some of the pipes that feed water to the hatchery. If they were damaged, replacements would be very expensive, she said.

The chemical sterilization of the hatchery will take about three days.

The annual process usually conducted in July was moved up because of the outbreak, Thompson said. Observers were being kept at safe distances.

"It's very toxic," she said.

Lahontan cutthroat are listed as a threatened species under the Endangered Species Act. Though protected, they are allowed to be caught by anglers because of hatchery production programs.

The hatchery raises about 600,000 cutthroat for annual release into the region's Truckee River and Pyramid and Walker lakes.

The hatchery met its goal of stocking Walker with 135,000 cutthroat this year, but won't be able to send any to Truckee-Pyramid because of the disease. Pyramid Paiute tribe officials said they would be able to provide plenty of stock from their own hatchery, however.

Still surviving in separate pools at the hatchery south of Gardnerville are 4,500 rainbow trout and a crucial brood stock of about 100 Pilot Peak cutthroat, Thompson said.