Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

MANAGEMENT OF SPONTANEOUS AUTOPOLYPLOIDY IN WHITE STURGEON Acipenser transmontanus CONSERVATION HATCHERIES

Paul Anders*, Andrea Schreier, Joel Van Eenennaam, Shawn Young,  and James Crossman
 
 Cramer Fish Sciences
Moscow, ID 83844
anders@fishsciences.net

Spontaneous autopolyploidy is a condition of genome duplication (increased chromosome number) that occurs between p arents and progeny within a species in the absence of hybridization or induction using traditional methods of thermal, pressure, or chemical shocks to produce triploid fish . This condition is known to occur in nine sturgeon species worldwide, including w hite sturgeon (Acipenser transmontanus ) in the Columbia  River Basin in the United States and Canada.  Although  this species is normally octoploid, having 8 copies of each chromosome (8N),  spontaneous autopolyploid w hite st urgeon (12N) have been recently confirmed in conservation and commercial white sturgeon production facilities in California and the Pacific Northwestern US and British Columbia, Canada . Some of t hese 12N individuals are fertile and when spawned with 8N fish can produce 10N progeny, which may have reduced fitness, performance, and reproductive viability. This condition in white sturgeon results from retention of the second polar body during meiosis, the same mechanism intentionally  used  in hatchery programs  to produce sterile triploid (3N) fish. Although s pontaneous autopolyploidy  in white sturgeon was initially documented in hatchery programs that artificially spaw n adult broodstock , a small number of wild (naturally-produced)  12N fish have  recently been confirmed.

W e briefly discuss  the  detection and  causes of spontaneous autopolyploidy  for white sturgeon  in the  conservation aquaculture setting and  describe  six  general  and 13 specific  Hatchery Best Practices to reduce the incidence and risks of spontaneous autopolyplo idy in such programs .  Recommended  Best Practices involve a range of activities from rigorous screening of broodstock and progeny groups to  collectively holding pre-spawning male and female broodstock and maintaining strict ranges of environmental conditions and handling protocols in the hatchery before , during , and after ovulation and spawning. While s pontaneous autopolyploidy in conventional  conservation hatchery programs can pose risks to recipient populations , implementing Best H atchery Practices  can significantly reduce the incidence  and risks  of 12N fish. Additional  focused studies to better understand the relationships between specific hatchery practices and the incidence of spontaneous autopolyploidy will help  sturgeon  culturists and hatchery managers  balance short-term  production and  population rebuilding goals with  the  need to  meet long-term population restoration and viability targets.