Endangered fish making comeback at lake

Friday, May 25, 2001 | 11:07 a.m.

The endangered razorback sucker fish is making a comeback in at least three bays along the northern edge of Lake Mead, a scientist reported Thursday.

For millions of years thousands of razorbacks lived in the Colorado River, but when the federal government began damming the river during the last century, the fish began to disappear, said researcher Paul Holden of Bio/ West, Inc., a company that has studied the razorback since 1996.

An estimated 50,000 to 100,000 razorbacks at one time inhabited Arizona's Lake Mohave, Holden told the Lake Mead Water Quality Forum meeting in Henderson Thursday.

In recent years the razorback population dropped to a few thousand, he said.

Plenty of the fish, which can live up to 40 years and can grow as long as 2 feet, lived in Lake Mead until the mid-1970s, when fishermen reported a decline in the razorbacks.

The fish are returning to Lake Mead, scientists say.

In March, scientists reported that toxins -- pesticides, heavy metals and chemicals -- that were flowing into the lake through the Las Vegas Wash may have been disrupting the male razorbacks.

Holden said the razorbacks spawn in three bays at the lake: Blackbird Point near Lake Mead Marina, Echo Bay and Grand Wash Bay.

Although one female razorback can lay up to 100,000 eggs, most of the larva are eaten or don't mature due to a lack of food and protective cover, Holden said.

Holden, who studies the fish for the Southern Nevada Water Authority and the Bureau of Reclamation, has videotaped a channel catfish following a female and eating the eggs as the fish spawned.

The ongoing research has provided scientists with a better idea of the natural cycle of razorback suckers that live along the river and its reservoirs, Holden said. Because of its lifespan, it's not necessary for the razorback to procreate every year to survive, he said.

Environmental biologist Zane Marshall of the Southern Nevada Water Authority, the regional water supplier, has taken an interest in the entire ecosystem of the Colorado River.

The water authority and the Bureau of Reclamation are funding Holden's research, Marshall said.