Pallid sturgeon : endangered species

Abstract

"Pallid Sturgeon were commercially harvested from the mid-1800s until they were listed as endangered in 1990. They were harvested primarily for their valuable eggs to make caviar. However, by far the largest threat to this species is thought to be habitat alteration associated with dams and channelization. The dams have impeded spawning migrations, potentially disrupted river flow spawning cues, and fragmented the Missouri River so larvae now drift into reservoir habitats where they cannot survive. Channelization and bank stabilization have reduced the variety of the Lower Missouri River and Mississippi River so there is not as much slow, shallow water. Because of this, there has been a huge reduction in the amount of habitat available for spawning and rearing, as well as reduced populations of the smaller native fishes the Pallid Sturgeon feeds upon. Pallid Sturgeon also have another unexpected disadvantage: their longevity. Although they can live 40 years or more, and females may not reach maturity until they are 7 to 15 years old, while males may take 5 to 7 years to become reproductively ready. This longevity, coupled with the time to reach maturity, makes them less adaptable to change and slow to respond to management actions designed to restore populations."--Page 2.