Genetic assessment of straying rates of wild and hatchery reared lake sturgeon (Acipenser fulvescens) in Lake Superior tributaries Jared J. Homola a, ⁎, Kim T. Scribner b,1 , Edward A. Baker c,2 , Nancy A. Auer d,3 a Department of Fisheries and Wildlife, Michigan State University, 27 Natural Resources Building, East Lansing, Michigan 48824, USA b Department of Fisheries and Wildlife and Department of Zoology, Michigan State University, 13 Natural Resources Building, East Lansing, Michigan 48824, USA c Michigan Department of Natural Resources and Environment, 484 Cherry Creek Road, Marquette, Michigan 49855, USA d Department of Biological Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, USA abstract article info Article history: Received 29 March 2010 Accepted 16 July 2010 Available online xxxx Communicated by Carol Stepien Index words: Lake sturgeon Straying mtDNA Lake Superior Natal philopatry in lake sturgeon (Acipenser fulvescens) has been hypothesized to be an important factor that has lead to genetically distinct Great Lakes populations. Due to declining abundance, population extirpation, and restricted distribution, hatchery supplementation is being used to augment natural recruitment and to reestablish populations. If hatchery-reared lake sturgeon are more likely to stray than naturally produced individuals, as documented in other well-studied species, outbreeding could potentially jeopardize beneficial site-specific phenotypic and genotypic adaptations. From 1983 to 1994, lake sturgeon propagated using eggs taken from Lake Winnebago adults (Lake Michigan basin) were released in the St. Louis River estuary in western Lake Superior. Our objective was to determine whether these introduced individuals have strayed into annual spawning runs in the Sturgeon River, Michigan. Additionally, we estimated a natural migration rate between the Sturgeon River and Bad River, Wisconsin populations. Presumed primiparous lake sturgeon sampled during Sturgeon River spawning runs from 2003 to 2008 were genotyped at 12 microsatellite loci. Genotypic baselines established for the Sturgeon River (n = 101), Bad River (n = 40), and Lake Winnebago river system (n = 73) revealed a relatively high level of genetic divergence among populations (mean F ST = 0.103; mean R ST = 0.124). Likelihood-based assignment tests indicated no straying of stocked Lake Winnebago strain lake sturgeon from the St. Louis River into the Sturgeon River spawning population. One presumed primiparous Sturgeon River individual likely originated from the Bad River population. Four first- generation migrants were detected in the Sturgeon River baseline, indicating an estimated 3.5% natural migration rate for the system. © 2010 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Introduction The predisposition of individuals to return to natal waters for reproduction has been widely described in many fishes and has important consequences at the individual and population levels (Leggett, 1977; Miller et al., 2001; Palmer et al., 2005). The ability of individuals to migrate to a distinct spawning area or to reside in a particular region often will result in reproductive isolation among populations (Leggett, 1977). Consequently, homing to natal sites can facilitate the evolution of beneficial site-specific genotypic and phenotypic adaptation over time. In sturgeon species, existing data suggest some degree of homing associated with natal philopatry (Auer, 1996; Stabile et al., 1996; Tranah et al., 2001), resulting in genetically distinct populations (DeHaan et al., 2006; Welsh et al., 2008). Site-specific adaptations can be jeopardized by interpopulation breeding when a particular strain of a species is stocked into an environment that differs from its origin. Outbreeding often reduces the fitness-related benefits gained through site-specific genotypic and phenotypic adaptation throughout subsequent generations (Lynch, 1991). This effect can be extended throughout an ecosystem by straying, resulting in reduced fitness for multiple populations (Edmands, 2007). Conversely, limited interbreeding between popula- tions can enhance gene diversity and reduce the risks posed by inbreeding in numerically depressed populations due to the presence of disadvantageous alleles, thereby improving fitness of offspring (Remington and O'Malley, 2000). Excessive straying of stocked individuals could quickly exceed the low number required for interbreeding to be beneficial. From 1983 to 1994, the Minnesota and Wisconsin Departments of Natural Resources stocked 864,500 lake sturgeon into the St. Louis Journal of Great Lakes Research xxx (2010) xxx–xxx ⁎ Corresponding author. Tel.: +1 517 432 4935. E-mail addresses: homolaj1@msu.edu (J.J. Homola), scribne3@msu.edu (K.T. Scribner), bakere1@michigan.gov (E.A. Baker), naauer@mtu.edu (N.A. Auer). 1 Tel.: +1 517 353 3288; fax: +1 517 432 1699. 2 Tel.: +1 906 249 1611; fax: +1 906 249 3190. 3 Tel.: +1 906 487 2353; fax: +1 906 487 3167. JGLR-00230; No. of pages: 5; 4C: 0380-1330/$ – see front matter © 2010 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.jglr.2010.08.011 Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr Please cite this article as: Homola, J.J., et al., Genetic assessment of straying rates of wild and hatchery reared lake sturgeon (Acipenser fulvescens) in Lake Superior tributaries, J Great Lakes Res (2010), doi:10.1016/j.jglr.2010.08.011