Examining early growth genetic potential of two distinct localities of Florida Bass and an F1 hybrid bass (Micropterus floridanus x Micropterus salmoides)

Abstract

The pursuit of trophy black bass (Micropterus spp.) is a challenge many freshwater anglers embrace. In addition, the growth of a trophy-sized specimen is a challenge fishery and hatchery managers have striven to solve for years. Florida Bass (Micropterus floridanus) have been long heralded for their higher maximal growth potential in comparison with northern Largemouth Bass (Micropterus salmoides) when stocked into optimal environments. For decades, stocking programs employing Florida Bass have occurred throughout the Southeastern United States with conflicting results. More recently, there has been increased interest regarding the growth potential of F1 hybrid bass (Micropterus floridanus x Micropterus salmoides). This has been of interest due to its potential for replacing Florida Bass in stocking, particularly in parts of the Southeastern United States. In addition, no studies have compared growth performance among phenotypically and/or geographically-distinct Florida Bass populations. In this thesis, Chapter 1 encompasses an extensive literature review on the topic. Chapter 2 discusses the current study, a pond experiment aimed at exploring early growth genetic potential between two Florida Bass populations and an F1 hybrid bass (M. floridanus x M. salmoides). For the current study, one Florida Bass population was sourced from a central Florida phosphate mine lake, which will be referred to as South Pasture in the remainder of this thesis; another was an established commercial strain under long-term culture and selection at the American Sportfish Hatchery (ASFH) in Pike Road, AL. The F1 hybrid bass (M. floridanus x M. salmoides) population resulted from pure Florida Bass and northern Largemouth Bass on-site at the American Sportfish Hatchery. All utilized broodfish were confirmed in their classification as pure Florida Bass or northern Largemouth Bass via single nucleotide polymorphism (SNP) genotyping. Using a common garden experimental model, the two populations of Florida Bass and the F1 hybrid (M. floridanus x M. salmoides) were mixed into common pond environments with optimal forage densities as juveniles, where their growth was monitored over eight months. Passive integrated transponder (PIT) tags were utilized to properly identify and compare each population. We observed significantly greater (p ≤ 0.05) final mean lengths (mm), weights (g), and relative weights (Wr) in F1 hybrid bass (M. floridanus x M. salmoides), in comparison to both populations of Florida Bass. F1 hybrid bass (M. floridanus x M. salmoides) also exhibited a significantly greater (p ≤ 0.05) overall growth rate than either Florida Bass population. The ASFH population had a greater percentage change in weight gain (199.30%), than the South Pasture population (121.57%). However, the South Pasture population had a greater overall increase in weight (70 g). The ASFH population also had a greater percentage/overall increase in length than the South Pasture population. The study highlights the variability in early growth genetic potential within Florida Bass, as well as, ultimately, advances the development of next-generation F1 hybrid bass utilizing superior Florida Bass individuals/strains.