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 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."
|onthenet usgs study|
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 — a lot of them — but apparently it's still a long roll of the dice to go from eggs to adult sturgeon.
That's proven by the fact that until last fall, no young-of-the-year pallid sturgeon had never 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," said Fuller. "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."
Mark Henckel is the outdoor editor of The Billings Gazette. He can be contacted at 657-1395 or at firstname.lastname@example.org.
|Shovelnose sturgeon doing swimmingly well
By MARK HENCKEL Gazette Outdoor Editor
Two close cousins, the shovelnose sturgeon and pallid sturgeon, exist side by side in the Missouri River system. The shovelnose population is thriving. The pallid population is disappearing.
How can that be?
"That's the million-dollar question," said Bill Gardner, Montana Fish, Wildlife and Parks biologist from Lewistown who works on pallids in the stretch of the Missouri River above Fort Peck.
"We think it has to do with the places where the species spawn and how long it takes for the (just-hatched) young to stop drifting with the current and settle into the river habitat," he said.
In the case of the Missouri above Fort Peck, Gardner said, shovelnose sturgeon run up the river and then far up the Marias River to spawn. It's 90 miles from Tiber Dam down to the mouth of the Marias and another 168 miles from the mouth to the headwaters of Fort Peck Reservoir.
"There is a lot of distance and drift time between the Marias and Fort Peck," he said. "We've gotten pallids just 15 miles above Fred Robinson Bridge. We suspect the pallids are trying to spawn way down low. They don't have as long a drift time before they hit Fort Peck. They're not reservoir fish and they just drop to the mud on the bottom and die."
Steve Krentz, a U.S. Fish and Wildlife Service supervisory biologist who leads the nation's Pallid Sturgeon Recovery Team, agreed.
"It may be related back to their drift distance," Krentz said. "Larval (just-hatched) shovelnose don't drift nearly as far in the water system and use the tributaries more to spawn. Pallids tend to be a bigger-river fish."
Gardner said that historic records indicate that pallid sturgeon used to run up as far as the mouth of the Marias. Perhaps bigger flows of warm water out of Tiber Dam might lure the pallids further upstream again.
"We know they used to spawn at the mouth of the Marias," he said. "Perhaps we can get better flows out of Tiber in years when there's more water and get them to do it again."
Shovelnose don't grow nearly as big as pallids. The Montana state record shovelnose weighed just 13.72 pounds. The biggest pallid caught in Montana weighed 60 pounds, and the species is known to grow as big as 80 pounds.