Status of an Introgressed Guadalupe Bass Population in a Central Texas Stream

Littrell, Bradley M.; Lutz‐Carrillo, Dijar J.; Bonner, Timothy H.; Fries, Loraine T.

doi:10.1577/m06-173.1

Cited by 26 publications

(28 citation statements)

References 36 publications

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“…; but see Littrell et al. ). Similar efforts to restore or supplement Shoal Bass populations are warranted and hold promise as a management and conservation tool, but careful selection of an appropriate broodstock source would be critical in determining the ultimate effectiveness of such conservation efforts.…”

Section: Discussionmentioning

confidence: 99%

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Genetic Population Structure of Shoal Bass within their Native Range

Taylor

Tringali

Sammons

et al. 2018

N American J Fish Manag

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Endemic to the Apalachicola River basin of the southeastern USA, the Shoal Bass Micropterus cataractae is a fluvial‐specialist sport fish that is imperiled because of anthropogenic habitat alteration. To counter population declines, restorative stocking efforts are becoming an increasingly relevant management strategy. However, population genetic structure within the species is currently unknown, but it could influence management decisions, such as brood source location. Leveraging a collaborative effort to collect and genotype specimens with 16 microsatellite loci, our objective was to characterize hierarchical population structure and genetic differentiation of the Shoal Bass across its native range, including an examination of structuring mechanisms, such as relatedness and inbreeding levels. Specimens identified as Shoal Bass were collected from 13 distinct sites (N ranged from 17 to 209 per location) and were then taxonomically screened to remove nonnative congeners and hybrids (pure Shoal Bass N ranged from 13 to 183 per location). Our results revealed appreciable population structure, with five distinct Shoal Bass populations identifiable at the uppermost hierarchical level that generally corresponded with natural geographic features and anthropogenic barriers. Substructure was recovered within several of these populations, wherein differences appeared related to spatial isolation and local population dynamics. An analysis of molecular variance revealed that 3.6% of the variation in our data set was accounted for among three larger river drainages, but substructure within each river drainage also explained an additional 8.9% of genetic variation, demonstrating that management at a scale lower than the river drainage level would likely best conserve genetic diversity. Results provide a population genetic framework that can inform future management decisions, such as brood source location, so that genetic diversity within and among populations is conserved and overall adaptability of the species is maintained.

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Section: Discussionmentioning

confidence: 99%

“…To determine the q ‐value threshold for “pure” Shoal Bass individuals, we followed Littrell et al. ().…”

Section: Methodsmentioning

confidence: 99%

Genetic Population Structure of Shoal Bass within their Native Range

Taylor

Tringali

Sammons

et al. 2018

N American J Fish Manag

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“…; Barton ; Littrell et al. ). While in most cases hybrids are less fit than the parental taxa (Coyne ), there are instances where first‐generation hybrid fitness may exceed both parental groups (i.e., heterosis or hybrid vigor), resulting in greater survival, growth rates, or overall body weight (Dunham ; Nielsen et al.…”

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confidence: 99%

Hybridization and Genetic Structure in Phenotypic Spotted Bass in Texas

et al. 2018

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Hybridization is common in fishes and can result in a wide range of outcomes. The capture of a world record phenotypic Guadalupe Bass Micropterus treculii raised questions about potential hybridization with Spotted Bass M. punctulatus. Subsequent, limited genetic sampling from the drainage (Colorado River) did not indicate hybridization in the world record sample or other phenotypic Guadalupe Bass, but phenotypic Spotted Bass produced unexpected genotypes. This called into question the assumed distribution of Spotted Bass in Texas. To address this disconnect, phenotypic Spotted Bass were acquired from drainages surrounding the Colorado River, ranging from central Texas to the Texas–Louisiana border, and the number of sequenced loci was expanded from one to seven. Results indicated that the westernmost extent of nonintrogressed Spotted Bass populations in Texas was the Trinity River. Phenotypic Spotted Bass west of this drainage were identified as Guadalupe Bass or hybrids. Admixed individuals identified in the San Antonio and Brazos River drainages (and previously in the Colorado River) may represent part of a hybrid zone. We also found that Spotted Bass from the Trinity River exhibited relatively large genetic divergence from Spotted Bass to the east and may represent the product of a vicariance event. Finally, we confirmed one mitochondrial and two nuclear taxa‐specific genetic markers for the efficient discrimination of these congeners and their hybrids. These markers should be useful for resource agencies attempting to enforce management regulations given the difficulty of identifying Spotted Bass by phenotype.

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“…), reduced stream flows (Bowles and Arsuffi ), and hybridization with introduced Smallmouth Bass M. dolomieu (SMB; Edwards ; Whitmore ; Littrell et al. ). Restoration efforts have included stocking hatchery‐reared GB fingerlings into select rivers (Fleming et al.…”

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confidence: 99%

The Early Life History of the Guadalupe Bass: Lessons for Culturing a Threatened Species

Prangnell

Matthews

2018

N American J Aquac

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Guadalupe Bass Micropterus treculii fingerlings are produced at the A. E. Wood State Fish Hatchery in San Marcos, Texas, and stocked into streams draining the Edwards Plateau in central Texas as part of a conservation program to restore threatened populations and combat hybridization with Smallmouth Bass M. dolomieu. Despite an intensive conservation effort, much of the early life history (including morphological development and first feeding characteristics) required for the intensive production of Guadalupe Bass is unreported in the mainstream literature. A better understanding of this critical period may improve culture practices, fingerling production, and management efforts. We documented spawning and early developmental characteristics and milestones over a temperature range of 20–24°C and the prey composition of Guadalupe Bass in a hatchery setting. Eggs and fry were photographed under a microscope and observed in culture tanks and ponds from initial stocking to fingerling harvest. A dominant‐male, polygynous spawning structure was confirmed. Egg incubation (28–29 growing degree‐days), larval development, yolk depletion, swim‐up, and life stage transition proceeded faster at higher temperature. Eggs (mean diameter, 2.1 mm), fry (mean hatchling TL, 4.7 mm), and yolk reserves (mean hatchling yolk volume, 2.02 μL) were larger than reported for Largemouth Bass M. salmoides. Normally developed fry commenced exogenous feeding on a variety of zooplankton soon after swim‐up (120–144 h posthatch and 6.95–8.05 mm TL at 23.4°C), while yolk was still present, and consumed progressively larger aquatic invertebrates over time. Swim‐up fry with a range in gape width of 0.75–0.89 mm readily consumed brine shrimp Artemia spp. nauplii as first feed. Guadalupe Bass appear to be a relatively pliable species, and current culture practices are generally sound. The observations presented can be used to refine culture and management practices.

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Status of an Introgressed Guadalupe Bass Population in a Central Texas Stream

Cited by 26 publications

References 36 publications

Genetic Population Structure of Shoal Bass within their Native Range

Genetic Population Structure of Shoal Bass within their Native Range

Hybridization and Genetic Structure in Phenotypic Spotted Bass in Texas

The Early Life History of the Guadalupe Bass: Lessons for Culturing a Threatened Species

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