Black Bass Diversity: Multidisciplinary Science for Conservation

Range-Wide Genetic Evaluation of the Suwannee Bass Reveals Divergent Lineages and Evidence of Small Founding Populations

Brandon L. Barthel, Wesley F. Porak, Michael D. Tringali, and David P. Philipp

doi: https://doi.org/10.47886/9781934874400.ch46

Abstract.—Suwannee Bass Micropterus notius have one of the smallest ranges of all the black basses. For decades, they were believed to only inhabit the Ochlockonee and Suwannee River drainages in Florida and Georgia. Over the past 15 years, additional populations have been discovered in the Wacissa, Wakulla, and St. Marks rivers in Florida, leading to speculation that these populations were created in the late 20th century through unsanctioned angler releases. Tissue samples were collected from Suwannee Bass inhabiting six streams in northern Florida in order to investigate this possibility and resolve genetic relationships across the species range. Nuclear DNA variation (11 polymorphic microsatellite loci and three allozyme loci) indicated that there was significant genetic differentiation between the fish inhabiting the Suwannee River drainage and those from the four streams to the west (i.e., the Ochlockonee River collection plus the three recently discovered populations). Analysis of molecular variance found that more than half of the nuclear genetic variation was partitioned between these two groups of collections. The fish from the two regions also had different ND2 gene sequences and private restriction fragment length polymorphism haplotypes. The consistent pattern of differentiation in the nuclear and mitochondrial genomes indicates that there are two stocks or subspecies of Suwannee Bass within the species range. The recently discovered populations were found to be genetically similar to fish from the Ochlockonee River and displayed genetic signals consistent with founding effects, as would be expected if these populations had originated from the release of a small number of individuals (potentially by anglers). However, the Ochlockonee River had similar genetic signatures, providing an example of a natural population of Suwannee Bass that is likely to have experienced natural bottlenecks due to low population size.