Management and Control of Invasive Asian Swamp Eel

Postdoctoral Research – The Asian Swamp Eel (Monopterus albus, Zuiew 1793) is a cryptic invasive species that has become established in several U.S. waterways.  In the 1990’s, a population was detected in several private ponds in Roswell, Georgia, and eels have since invaded adjacent wetland habitats of the Chattahoochee River.  My research is aimed at: 1) characterizing the ecology of Asian Swamp Eel in this invaded ecosystem (e.g., age and diet studies); 2) quantifying the scope of the invasion (i.e., population size and extent); and 3) examining control and removal strategies.  Because the species is cryptic and difficult to sample, I am undertaking a genotype-by-sequencing approach wherein informative SNPs will be used to reconstruct parentage and estimate family sizes.

Funding: National Park Service; Partners: USFWS, GADNR, GA Power, OK Coop Unit, and OK State



Population Genetics of Neosho Smallmouth Bass

Co-Principal Investigator – In the springfed streams of the Ozark Highlands and Boston Mountains of Oklahoma, Missouri, and Arkansas swims an endemic sportfish, the Neosho Smallmouth Bass (Micropterus dolomieu velox, Hubbs and Bailey 1949).  We investigated hybridization with stocked, non-native congeners and delineated population boundaries for this native subspecies.  We discovered high rates of introgression with non-native “Tennessee lake-strain” Smallmouth Bass upstream of Lake Tenkiller, which was stocked in the early 1990’s.  We also found that larger streams were more vulnerable to the invasion of non-natives and subsequent introgression.  Interestingly, these areas also harbored the highest levels of genetic diversity in Neosho Smallmouth Bass, highlighting a challenge for conserving native genetic diversity.  Finally, we uncovered three population boundaries relevant to management activities like supplemental stocking.

Funding: Peoria Tribe of Oklahoma; Partners: ODWC, USFWS, MDC, OK Coop Unit, and OK State



Occupancy and Distribution of the State-Endangered Longnose Darter

Invited Collaborator – The Longnose Darter (Percina nasuta, Bailey 1941) was historically known from at least two river systems in Oklahoma, but was apparently extirpated from the Poteau River basin following reservoir construction.  In the early 1990’s, managers translocated Longnose Darters from Lee Creek into the Poteau system (Blackfork Creek; read more here); however, whether Longnose Darters persisted is unknown.  Further, the population status in Lee Creek is also uncertain.  We are using range-wide niche models to narrow down optimal sampling locations, then sampling selected sites in both systems to quantify detection probabilities for Longnose Darters and co-occuring darter species.  At present, the reintroduction effort in Blackfork Creek appears to have been unsuccessful, suggesting Lee Creek is now the only stream that supports Longnose Darters in Oklahoma.  This project is being completed by Colt Holley, a Master’s student at Oklahoma State, and advised by Dr. James M. Long.

Funding: ODWC; Partners: OK Coop Unit and OK State



Influences of Fragmentation on Fluvial Specialist Black Bass Species

Dissertation – I used a combination of species distribution models and population genetics to uncover how riverscape fragmentation has contributed to range loss of the Shoal Bass (Micropterus cataractae, Williams and Burgess 1999), as well as how to best conserve remaining genetic diversity across the species’ native range.  I paired these range-wide approaches with two fine-scales studies that: 1) examined the role of impoundments and non-native congener species in introgression and species turnover, and 2) linked population dynamics to landscape and hydrology.  Results of these studies are actively being used to inform a range-wide Shoal Bass management plan and watershed-scale conservation actions through SARP’s Native Black Bass Initiative.  These results also provide a broader context for conservation of native biodiversity in fragmented stream ecosystems.

Funding: National Park Service; Partners: GADNR, USFWS, GA Power, FWC, ODWC, GPCESU, SARP, OK Coop Unit, and OK State





Non-native Smallmouth Bass in the Chattahoochee River 

Master’s and Dissertation Side Project – In the early 2000’s, an angler illegally transplanted Smallmouth Bass from the Tennessee River system into the Chattahoochee River downstream of Morgan Falls Dam.  This reach is home to native Shoal Bass (Micropterus cataractae, Williams and Burgess 1999) and Chattahoochee Bass (M. chattahoochae, Baker et al. 2013).  To examine the potential for reproduction and dispersal within this thermally depressed system, I used spatially-explicit interpolation of water temperature data.  Results suggested that Smallmouth Bass could reproduce and expand downstream from Morgan Falls Dam, but warmer water temperatures in the summer may “squeeze” Smallmouth Bass back upstream nearer Morgan Falls Dam.  A follow-up genetic study demonstrated that up to six black bass taxa (yes, six!!!) were involved in hybridization below Morgan Falls Dam, suggesting conservation-stocking of pure Shoal Bass may be necessary to sustain the native fishery.  Comparisons of fish phenotypes to genotypes may help managers identify non-natives and hybrids in the field for potential removal efforts.

Partners: UGA, GADNR, NPS, FWC, OK Coop Unit, and OK State

Shoal Bass (native)

F1 Shoal x Smallmouth

Smallmouth Bass (non-native)



Status Assessment of a Shoal Bass Population in the Lower Flint River, Georgia

Master’s Thesis – Working alongside management biologists to develop research objectives, I combined mark-recapture, genetics, and telemetry to assess the status of a Shoal Bass population in a 50-km reach of the lower Flint River, Georgia, situated between two impoundments.  I designed a mark-recapture study that estimated approximately 200 adults were aggregated within a large shoal complex during the spawning season, which could serve as a benchmark for future population monitoring.  I assessed the genetic purity of Shoal Bass throughout the lower Flint River and Ichawaynochaway Creek, a major tributary.  Microsatellite DNA markers diagnosed low levels of hybridization with with non-native Spotted Bass throughout the system, with highest hybridization levels just downstream of the Flint River Dam.  The radio telemetry study determined that the majority of Shoal Bass translocated from fluvial habitats downstream into impoundments during fishing tournaments likely survive and return to upstream habitats, although a small percentage of fish were lost from the population.  Overall, the Shoal Bass population in the lower Flint River represented one of the most robust populations remaining of the species.

Funding: UGA and GADNR; Partners: FWC and Joseph. W. Jones Ecological Research Center





Meristic Variation Among Populations of Redeye Bass

Undergraduate Thesis – I leveraged existing ichthyological collections and contemporary sampling efforts to characterize variation among Redeye Bass (Micropterus coosae, Hubbs and Bailey 1940) from four major river drainages in Georgia (Mobile, Chattahoochee, Altamaha, and Savannah).  I examined a series of meristics, morphometrics, and pigmentation traits to identify characters that could reliably discern among the “forms” examined.  This work was a precursor to the description of Chattahoochee Bass (M. chattahoochae, Baker et al. 2013) and set the stage for forthcoming species descriptions of two putative taxa, “Bartram’s Bass” from the Savannah River drainage and “Altamaha Bass” from the Altamaha River drainage (both M. sp. cf. cataractae, Freeman et al. 2015).  Partners: Georgia Museum of Natural History and UGA.





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All photographs and content (C) Andrew Taylor, 2018.  Do not use without explicit written permission.