Experts say fish becoming too old, not a healthy spawning population.

BILLINGS (AP) - Survival as a species is really simple, whether you're talking about man, beast or the pallid sturgeon. You replace yourself before you die.

If you have young and replace yourself in the population, then have more of your offspring survive to adulthood, your species grows in number. If you don't replace yourself and others don't replace themselves either, your species goes down in numbers.

In the case of the endangered pallid sturgeon, no replacement of the dying has been going on for at least 35 years - perhaps longer - on the Missouri and Yellowstone rivers of Montana. Pallid sturgeon are on the fast track to extinction.

"The wild pallids we have right now are about 35-to-50-plus years old. There are no younger sturgeon coming up behind them," said Steve Krentz, a U.S. Fish and Wildlife Service supervisory biologist in Bismarck, N.D., who leads the nation's Pallid Sturgeon Recovery Team.

"Their average age is 40 to 50 years old," he said. "Within 10 years, a lot of them will be maxing out at 55 to 60 years of age. By that time, there will be so few fish that when they do go to spawn, finding another sturgeon may be very difficult."

It could be argued that a single, lonely sturgeon at spawning time is already having a hard time finding a willing mate. And that's in the stretch of the Missouri River above Fort Peck Reservoir and the stretch below Fort Peck Dam downstream to Lake Sakakawea, including the lower Yellowstone River, the areas considered to have the best remaining pallid sturgeon habitat in the world.

Montana Department of Fish, Wildlife and Parks' Ken McDonald, who chairs the Upper Missouri Basin Pallid Sturgeon Recovery Work Group, said FWP biologist Bill Gardner pegs the pallid population above Fort Peck at 30 to 50 adults.

Below Fort Peck Dam, pallid biologist Kevin Kapuscinski reports there are as few as 16, perhaps up to 200 adults.

"Kevin also feels some of those pallids may be so old that they're approaching the age when they become senescent - too old to reproduce," McDonald said. "It's not a healthy spawning population."

Complicating reproduction and replacement further is the fact that pallid sturgeon don't spawn every year. It also takes many years before they even begin to spawn.

"We estimate males don't reach spawning age until sometime between 5 and 10 years old. It takes females 10 to 20 years to mature," Krentz said. "Males may have the potential to spawn every year, but females will only spawn every two to six years."

When Krentz starts crunching those numbers, then factors in that male pallids outnumber female pallids by at least 3-to-1, or perhaps 4-to-1, or sometimes even 5-to-1, the number of females that could be spawning in any one year is dismally low.

"Below Fort Peck Dam, with a total population of somewhere less than 200 pallids, that would mean less than a dozen to 20 females will be trying to spawn in any given year. It's probably fewer in number than that," Krentz said. "Above Fort Peck, it's probably less than a handful of female pallids in any given year. That's one of the complicating factors. When you're looking at one or two or three fish in a whole stretch of river, it's about like a needle in a haystack."

He said female pallids can deposit five to 10 pounds of eggs but apparently it's still a long roll of the dice to go from eggs to adult sturgeon.

That is proven by the fact that until last fall, no young-of-the-year pallid sturgeon had been found by biologists above or below Fort Peck Reservoir.

Then, last fall, on Sept. 4 and 5, FWP biologist Dave Fuller and U.S. Geological Survey biologist Pat Braaten netted two larval pallid sturgeon below the confluence of the Yellowstone and Missouri rivers.

"We made history finding those two little pallids," Braaten said. "They were small. We thought they were pallids, but we had to send them off to Dr. Darrel Snyder (at Colorado State University's Larval Fish Laboratory) for verification."

The little pallids were exactly 21.6 and 23.1 millimeters long, less than an inch each. Snyder determined they were, indeed, pallids. They were the first evidence of successful spawning found in the 300-mile reach of these rivers in recent times.

"We need to do something to encourage spawning by the remaining pallid sturgeon we have," Fuller said. "There aren't that many pallids left, but if we can help them to spawn, hopefully that will give this species a chance to recover before it's too late."