Detection of rare species can be challenging and time‐consuming using conventional methods, but environmental DNA (eDNA) is becoming a commonly used tool for detection in conservation and management of species. This study demonstrates the utility of the precipitation method (precipitated and preserved in 3 M sodium acetate and 95% ethanol) for collection of eDNA to detect the seasonal distribution of the critically endangered Alabama sturgeon (Scaphirhynchus suttkusi). Surface and benthic water samples were collected across a wider geographic area than previously published for Alabama sturgeon eDNA. Surface and benthic samples both yielded detections and resulted in a similar proportion of positive detections to previous work. However, by sampling a greater portion of the distribution of the Alabama sturgeon, further insight was provided on potential sturgeon movement. The results of the precipitation method show that Alabama sturgeon detections increase during spawning months, and that the fish may be overwintering in the Tombigbee River. High detections from winter benthic samples suggest that habitat choice may play a role in detectability and highlight the need to consider natural history when designing environmental DNA studies. When designing environmental DNA collection for rare species, sampling design should factor in species ecology, habitat use, site characteristics, and specific questions driving the research.

We compared the genetic diversity and structure between wild and captive-propagated freshwater mussels at risk in Canada, Lampsilis fasciola (Wavy-rayed Lampmussel, WRL) and Ptychobranchus fasciolaris (Kidneyshell, KS), using microsatellite generated genotypes. No significant differences were detected between wild and propagated WRL (from 12 mothers) or KS (from 7 mothers) based on genetic diversity metrics using Kruskal-Wallis tests. Effective population size (Ne) was estimated and there was considerable overlap in the estimated Ne between wild and captive populations of both species. Pairwise FST and Dest values among wild WRL, hatchery-raised WRL juveniles, and across different time periods (2008 to 2018) were generally low (FST = 0.007-0.043, Dest = 0.005-0.282). Pairwise FST and Dest for KS were not significant and low (0.012, 0.017). When comparing captive-reared offspring with the wild population, STRUCTURE analysis revealed strong support for a single genetic population. With at least 7 females contributing to brood stock, genetic diversity was maintained. Further research is needed to assess the male contribution to each glochidial brood, and the variability of genetic diversity in individual glochidial broods.

Obovaria olivaria is a species of freshwater mussel native to the Mississippi River and Laurentian Great Lakes‐St. Lawrence River drainages of North America. This mussel has experienced population declines across large parts of its distribution and is imperiled in many jurisdictions. Obovaria olivaria uses the similarly imperiled Acipenser fulvescens (Lake Sturgeon) as a host for its glochidia. We employed mitochondrial DNA sequencing and restriction site‐associated DNA sequencing (RAD‐seq) to assess patterns of genetic diversity and population structure of O. olivaria from 19 collection locations including the St. Lawrence River drainage, the Great Lakes drainage, the Upper Mississippi River drainage, the Ohioan River drainage, and the Mississippi Embayment. Heterozygosity was highest in Upper Mississippi and Great Lakes populations, followed by a reduction in diversity and relative effective population size in the St. Lawrence populations. Pairwise FST ranged from 0.00 to 0.20, and analyses of genetic structure revealed two major ancestral populations, one including all St. Lawrence River/Ottawa River sites and the other including remaining sites; however, significant admixture and isolation by river distance across the range were evident. The genetic diversity and structure of O. olivaria is consistent with the existing literature on Acipenser fulvescens and suggests that, although northern and southern O. olivaria populations are genetically distinct, genetic structure in O. olivaria is largely clinal rather than discrete across its range. Conservation and restoration efforts of O. olivaria should prioritize the maintenance and restoration of locations where O. olivaria remain, especially in northern rivers, and to ensure connectivity that will facilitate dispersal of Acipenser fulvescens and movement of encysted glochidia.

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Our study documents and analyzes the absence of genetic diversity and structure of the freshwater mussel (Bivalvia: Unionidae) Quadrula quadrula (Rafinesque 1820), Mapleleaf, in the Lake Winnipeg, Assiniboine River, and Red River drainages (Manitoba, Canada). Previous studies have revealed patterns of genetic diversity and structure in the Mississippi and Ohio river drainages, and the Laurentian Great Lakes drainage. Genotypes from six variable microsatellite loci showed that the Q. quadrula population in Manitoba was significantly differentiated from the population in the Great Lakes drainage (Ontario), supporting the existence of two Designatable Units in Canada. Conversely, there was no evidence of genetic structure within the sampled range of Q. quadrula in Manitoba. The lack of genetic structure in Q. quadrula across its distribution in Manitoba reflected their post-glacial history and use of a vagile host and necessitates that efforts should be made to ensure connectivity and maintain gene flow across the region. Given that the evidence suggests that Manitoba Q. quadrula belong to a single genetic population, movement of hatchery-propagated juvenile Q. quadrula, adult Q. quadrula, or glochidia-carrying host catfish sourced from any location in Manitoba could be used to augment declining populations or at-risk locations in Manitoba.