Incidence of spontaneous autopolyploidy in cultured populations of white sturgeon, Acipenser transmontanus

• We detected spontaneous autopolyploids in white sturgeon conservation aquaculture.
• 12/150 individuals examined had a genome size 1.5x that of normal white sturgeon.
• Two half sibling families had a high prevalence of autopolyploids (26%, 33%).
• Spontaneous autopolyploidy in white sturgeon may be connected to the male parent.

Many fish of aquacultural importance including sturgeon and paddlefish have a history of polyploidy in their evolutionary lineages. Spontaneous autopolyploids have been detected in several sturgeon species in culture despite the fact that the induction of triploidy is not a management tool in farming sturgeon for meat and caviar. In 2010, we discovered two female spontaneous autopolyploid white sturgeon (Acipenser transmontanus) on a commercial caviar farm that had successfully produced offspring of intermediate ploidy in crosses with normal males. Here we use flow cytometry and microsatellite genotyping to screen a second aquaculture program for the presence of spontaneous autopolyploids. Flow cytometry of female parents and their progeny in the 2011 year class created by the Kootenai River white sturgeon conservation aquaculture program revealed that wild caught females used as dams possessed normal ploidy (8N). Five of ten families sampled from the 2011 year class contained spontaneous autopolyploids possessing DNA content consistent with dodecaploidy (12N). The percent of autopolyploid individuals sampled ranged from 0 to 33% per family, and the total number of spontaneous autopolyploids in the 2011 year class was 12/150 (8%). Microsatellites were not useful in detecting spontaneous autopolyploids in the conservation aquaculture program due to low levels of genetic diversity in the endangered Kootenai River population. The two families with the highest incidence of spontaneous autopolyploids (33% and 26% of offspring sampled) were sired by a single male, suggesting a paternal effect on the generation of spontaneous autopolyploids in white sturgeon.