Pallid sturgeon have a long lifespan, living in excess of 50 years and
perhaps as long as 100 years. They lack bones and scales which makes it more difficult to establish their age and determine exactly how long they live.
As is true for many long-lived species, pallid sturgeon reach reproductive maturity relatively late. Males reach sexual maturity between the ages of 5 and 7 years, while females are believed to become capable of reproduction when they are at least 15 years old. One study of nine females indicated that they begin egg development between the ages of 9 and 12 years, but do not reach reproductive maturity until they are 15 years old.
Reproduction does not take place every year; the average interval between spawning is three years, although other studies suggest an interval as long as ten years. Spawning usually takes place between the months of May and July. Prior to the construction of dams on the Missouri, pallid sturgeon migrated hundreds of miles upstream to spawn, and would seek out rocky or hard surfaces to deposit hundreds of thousands of eggs. One female pallid sturgeon that was caught in the upper Missouri River was estimated to be carrying 170,000 eggs, representing over 11 percent of its total body weight.
After fertilization, pallid sturgeon eggs hatch in 5 to 8 days, after which the larvae drift back downstream for several weeks. As the larvae develop tails, they seek out slower moving waterways and slowly mature over a period of a dozen years.
The rate of survival to maturity for pallid sturgeon larvae is extremely low and of the hundreds of thousands of eggs spawned, only a small handful lives to adulthood. For several decades, no natural reproduction of pallid sturgeon was observed, since all the pallid sturgeon that had been captured were older specimens.
However, in the late 1990s, young pallid sturgeon were discovered living in a restored riparian area of the lower Missouri River. This was the first documented example of wild spawned pallid sturgeon in 50 years. In 2007, two female pallid sturgeon were also reported to have spawned in the Missouri National Recreational River area located downstream from Gavins Point Dam on the Missouri River.
A pallid sturgeon crew captured a spawning female at Yellowstone River mile 6.8 on June 19, 2011 when the water temperature was 20.5 C and flow was 21,500 cfs. This is the same area where a spawning female was observed a few years ago. The spawning area is a deep swift area that was inhabited by several males. The crew sampled for free embryos and captured one in this area. The embryo was sent for genetics work and it turned out it was a pallid sturgeon but from a different non-transmittered female. So at least two females were spawning, and at least one successfully, in this area in 2011.