Fisheries & Wildlife Science: Theses

Life history traits in ectotherms are tied to environmental temperature, and many species exhibit morphological and behavioral differences in thermally different habitats. Although these differences are generally attributed to differences in thermal regimes between habitats, most prior research on this topic has been performed across latitudinal or altitudinal gradients. Consequently, I wanted to determine if differences in morphology and behavior are also present among populations of Sceloporus consobrinus that inhabit thermally different habitats at the same latitude and elevation.

In this study, I chose sites that fit one of two habitat types: warmer open rocky habitat and cooler, more vegetated forested habitat. Throughout 2013 and 2014, I monitored temperature in the two habitats to verify that they differed in thermal regime. Between April –July 2013 and 2014, I captured 267 individuals and collected data on morphology, thermoregulatory behavior, microhabitat use, and predation. I filmed 98 lizards and quantified behavior to determine if lizards in different thermal environments differed in rates of thermoregulatory and non-thermoregulatory behaviors. I also monitored and compared activity throughout the year in both habitats to determine if differences existed and were associated with thermal differences between the habitats.

Although the rocky habitat was warmer throughout the year, I found no difference in snout-to-vent lengths (SVL) or weights of lizards in the two habitat types. Similarly, I found little difference in rate of thermoregulatory behaviors in lizards between the two habitats, although there was a difference in the time of day lizards were active. Body temperature of active lizards was also similar between the two habitats. These results suggest that morphological differences found in previous studies for populations in thermally different habitats may be due to a combination of other factors associated with differences in latitude or elevation.

Paddlefish Polyodon spathula are a valuable commercial species throughout much of their range including Lake Dardanelle, one of the most important commercial paddlefish fisheries in Arkansas. While fecundity, mortality, and age and growth of paddlefish stocks in Lake Dardanelle have been assessed previously, information on their movements, habitat utilization, and commercial harvest rates is lacking. To help fill this information gap, 39 paddlefish were tracked a minimum of once per month from October 2014 through September 2015. Habitat selection was determined for eight macrohabitat types and four bathymetric habitat types by comparing percent usage to percent availability. Four high-use (≥10%) and four moderate-use (4-10%) areas were identified. Paddlefish preferred deep pools and bays with relatively large tributaries. Median linear range was 1.9, 20.9, 1.2, and 9.7 km in winter, spring, summer, and fall, respectively. All seasonal differences were significant (all P < 0.020) except winter and summer (P = 0.486). As many as 14 individuals may have emigrated during a major flood event in the summer of 2015. Downstream emigration was confirmed for two individuals that were detected below Dardanelle Dam. Spawning runs were observed for nine paddlefish that likely spawned below Ozark Jeta-Taylor Dam when water temperatures were between 10 and 18 oC. Commercial fishing mortality on telemetered fish was 13% during the 2014-15 and 2015-16 commercial paddlefish seasons combined. Knowledge gained from this study will help managers maintain a viable and commercially productive paddlefish population in Lake Dardanelle.

State parks serve a dual conservation role by offering protected habitat to many species while also promoting recreational use of natural resources. Non-consumptive recreation activities, however, have long-term negative effects on the behavior, physiology, and reproductive success of state park biotic communities. The purpose of my research was to investigate the possible synergistic effects of non-consumptive trail use, environmental factors, and trail design factors on avian, mesocarnivore, and woody vegetation communities in Arkansas state parks. During 18 May – 7 August 2015, I conducted avian point counts, trail user counts, set camera traps, and sampled vegetation at 227 points on the main trail systems of 4 Arkansas state parks. I quantified community richness, evenness, and diversity for each taxon and used a series of 1-way ANOVAs and Kruskal-Wallis tests to examine differences in communities at regional and local scales. I also created 3 candidate model sets (e.g., richness, evenness, and diversity) for each taxonomic community in each park and used AICc and regression analyses to determine whether synergistic effects influenced biotic communities in the parks. These data were further used to create detection maps of flagship avifauna and to evaluate the efficacy of a pilot citizen science program in the parks. Differences in communities were predominantly restricted to the local scale and found in evenness and diversity values of avian (F3,22 = 9.57 – 17.8 P = 0.001 – 0.003) and understory vegetation communities (F3,22 = 7.38 – 9.41 P ≤ 0.001). Non-consumptive trail use was a strong predictor for avian richness (relative Akaike weight ω = 0.85) and diversity (ω = 0.70 – 0.84), however, vegetation communities and attributes were stronger determinants of the other biotic communities. Detection probabilities (0.00 – 0.99) for the 5 focal avifauna varied in response to a spectrum of trail use rates and response rates were low (2%) for the citizen science and human dimension surveys. In general, my results indicate the need for a holistic management strategy that addresses the collective anthropogenic and local environmental effects that influence park taxonomic communities while actively incorporating the public in those conservation goals.

Road crossings on small streams typically alter stream hydrology and potentially fragment aquatic ecosystems. The Ouachita National Forest, Arkansas has thousands of road crossings which may hinder fish movement and contribute to genetic inbreeding or extirpation. To monitor the impacts of road crossings on fish movement, I used stationary antenna arrays to detect and record radio frequency identification tags (RFID, also known as PIT tags) in the Ouachita Mountains. From 2011-2013, I marked ∼3,800 fish (nine species) 85 mm or longer total length with 12-mm, half-duplex, RFID tags. I installed remotely-powered RFID detection stations in two streams with road crossings and two reference streams without road crossings to continuously monitor fish movements. The RFID stations included two, pass-through antennas transecting the stream, with one antenna upstream of the road crossing or reference reach and the other located downstream. The two-part antenna array was designed to precisely record timing and movement direction of each fish passage. The antennas lacked rigid in-stream structures, which may have affected fish movement and I developed a crossover antenna design to improve tag detection efficiency. I monitored associated stream depths and velocities to characterize hydrological conditions and road crossing hydraulics. Fish passed at higher rates across reference reaches than road crossings and at higher rates across a box-culvert than a vented-ford, where fish utilized high water events to bypass high velocity and low swimming depth barriers. Stream intermittency caused extensive stream dryness and exacerbated the hydraulic obstacles at road crossings, which reduced passage rates. Fish species and length had little impact on passage rates but Longear Sunfish did move significantly shorter distances than Creek Chub and Highland Stonerollers. The RFID stations monitored fish passage more efficiently than electrofishing recapture methods and should enhance future studies of aquatic organism passage and road crossing permeability.

Channel Catfish Ictalurus punctatus have an important role in Arkansas’s commercial and recreational fisheries. This importance promoted sampling strategy investigations for obtaining information that assist with future management decisions. My study focused on determining effective sampling effort and sample size requirements needed for detecting changes in relative abundance within Channel Catfish populations, and explored relationships between catch per unit effort (CPUE) and reservoir habitat characteristics. My study was conducted during the spring of 2014 in six reservoirs (Lake Nimrod, Lake Overcup, Lake Catherine, De Queen Lake, Lake Erling, and Lake Columbia). General stock assessments consisting of length frequency distributions, growth rates, and mortality rates were also conducted for each reservoir. Sampling involved setting 16 tandem hoop net sets during April, May, and June in each reservoir. Mean CPUE (fish/tandem hoop net set) ranged from 1.9 (SD, 2.1) to 355.9 (SD, 137.2). Lake Erling’s CPUE was the greatest, while Lake Catherine’s CPUE was the lowest. In addition, catch rates were influenced primarily by water temperature. Shallow reservoirs had higher CPUE than deep reservoirs for each month sampled. In addition, the CPUE of each reservoir’s lower section (closer to the levee) was less than the upper section during April. However, both sections were equal during May and June. Due to April’s low catch rates, only May and June’s CPUE were used to determine effective sample sizes. The greatest mean back-calculated length-at-age for Channel Catfish sampled occurred in Lake Overcup, while the greatest mean length-at-capture occurred in Lake Columbia. Growth rates were also significantly different between reservoir types for back-calculated ages two, four, five, and seven. Finally, shallow reservoir types displayed higher mortality rates than deep reservoirs. Sample size simulations were conducted to determine the number of sets necessary to detect 10% to 50% changes in relative abundance at an alpha of 0.05 and 0.10 and power of 0.95 and 0.80. Simulations revealed CPUE assessments ineffective at describing populations without also assessing age and growth data and length frequency distributions. Furthermore, angler surveys and harvest estimates could be a potential alternative to CPUE for evaluating a population’s relative abundance.

The interior least tern (Sternula antillarum athalassos) is an endangered shorebird that nests on sandbars in river systems throughout the central United States, and which has lost habitat due to damming and channelization of these rivers. My study sought to quantify the status and trends of the population nesting in the McClellan-Kerr Arkansas River Navigation System (MKARNS) within Arkansas, and to establish best practices for nesting habitat management. The local population of terns remained steady between 2010 and 2014, with approximately 450 adults breeding in this section of MKARNS. Regression tree analysis and principal component analysis showed that colonies on unconnected islands at wide spots in the river away from dike fields and the downstream side of dams had the highest yearly measures of productivity. I make recommendations for dredge spoil deposition in locations matching these characteristics in order for the U.S. Army Corps of Engineers to meet its legal requirement to manage least tern habitat within MKARNS.