Genetic screening for nonnative black bass introductions and introgression in Ohio waters
Kevin S Page, Joseph D Conroy, Richard D Zweifel, Honggang ZhaoAbstract
Objective
Florida Bass Micropterus salmoides and Alabama Bass M. henshalli have been introduced outside their native ranges in an effort to improve local fisheries. Introductions may negatively impact fisheries for native black bass Micropterus spp. through competition and introgression. To protect native black bass fisheries in Ohio, introductions of Florida Bass and Alabama Bass have been banned. Understanding the prevalence of nonnative black bass in Ohio and the degree to which introgression may be occurring within native black bass populations would be helpful for limiting and mitigating the impacts of nonnative black bass.
Methods
Tissue samples were collected from 486 black bass from 33 locations across Ohio. Specimens were putatively assigned as native Largemouth Bass M. nigricans, Smallmouth Bass M. dolomieu, or Spotted Bass M. punctulatus based on morphology. Black bass species-specific genetic markers (single-nucleotide polymorphisms) were employed to verify black bass species identity. Fish genetically assigned as Largemouth Bass were further screened to determine if these fish were pure Largemouth Bass, Florida Bass, or hybrids between the two species.
Result
No pure nonnative species were identified among the samples screened. Florida Bass alleles were discovered among all “Largemouth Bass” screened (n = 11) from one reservoir (Lake Snowden) and one fish from the Ohio River. A hatchery managed by a local college is believed to be the source of Florida Bass alleles in the reservoir. The source of Florida Bass alleles found in the one fish from the Ohio River is unknown.
Conclusion
Nonnative black bass do not appear to be a current threat to native black bass fisheries in Ohio. Evidence of Florida Bass introgression was limited to two locations. Maintaining and enhancing black bass fisheries should focus on leveraging local population and fishery characteristics while preventing introductions of nonnative black bass. Routine genetic monitoring is needed to identify and mitigate future introductions and introgression.