My lab's research reflects my broad training in fish and aquatic ecology and topics we study range from basic biological and ecological questions to applied fisheries research. I enjoy working closely with resource agencies and many of my projects are in collaboration them. Recently, research in my lab has focused on population biology, exploitation of managed species, ecological modeling, age estimation, and early life history.
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Current Projects
Estimating abundance, exploitation, and mortality associated with catch-and-release angling of Muskellunge in the southern portion of their distribution.
Muskellunge support important freshwater fisheries throughout their distribution and anecdotal evidence suggests increasing popularity of Muskellunge fishing (e.g., development of destination fisheries, Muskellunge angling groups, and Muskellunge focused guide services). Given the popularity of these fisheries, angling groups have taken interest in their long-term sustainability despite low levels of harvest because catch-and-release mortality has been documented as an important source of mortality for a variety of recreationally important species, even when it occurs at low levels, Because mortality of fish that are angled and subsequently released is partially a function of stress related to water temperature, and Muskellunge in the southern portion of their distribution are more likely to experience stressful temperatures during summer months than in more northerly locations, we are conducting a collaborative effort involving agency biologists, universities, and anglers to quantify catch-and-release mortality of Muskellunge in the southern portion of their distribution. CCU is leading the research efforts on the James River, VA in collaboration with the the Virginia Department of Wildlife Resources (Scott Smith, George Palmer, Tyler Young). WVU (Dr. Kyle Hartman and M.S. students Peter Jenkins and Taylor Booth) in collaboration with the West Virginia Division of Natural Resources (Jeff Hansbarger) are leading field efforts on Stonewall Jackson Lake and pond experiments in four additional states (in collaboration with resource agencies in WI, NC, VA, and MD). For more information on this project please see the link to the project website below.
Catch-and-Release Mortality Website
Catch-and-Release Mortality Website
Estimating recruitment of juvenile Atlantic Sturgeon in South Carolina Rivers
Atlantic Sturgeon are federally listed as Endangered, and to develop the knowledge necessary to conserve and promote recovery of Atlantic Sturgeon populations, the Atlantic States Marine Fisheries Commission established research and data collection priorities for the species. One of the priorities is to estimate how many young Atlantic Sturgeon are entering different populations each year, and this is where CCU’s involvement in Atlantic Sturgeon research begins. We are collaborating with the SCDNR (Bill Post, Ellen Waldrop, Danielle Carty) on a field study to estimate how many one-year old sturgeon are in Winyah Bay and the rivers draining into it in a given year. In addition to completing a field study for sturgeon in the Winyah Bay system, we are using long term capture-recapture data to estimate growth and annual abundance of juvenile sturgeon in the Edisto River and investigate potential relationships between growth, abundance, and environmental factors. Determining the number of young fish in a population can help us understand how populations change over time, and the effect of environmental disturbances (e.g., major floods) on the reproductive success of spawning adults.
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Use of chemical marking in age validation of fishes
Oxytetracycline (OTC) has long been used to fluorescently mark calcified tissues (e.g., bones, otoliths) in fishes and serve as a biological time stamp. The mark associated with immersion in or injection with OTC has been used to identify hatchery fish stocked into lakes, rivers, and marine habitats, validate age estimation methods, and examine relationships between body growth (changes in length) and calcified tissue growth. It has been assumed that OTC marks are only visible when structures are viewed using an epifluorescent microscope. However, recent independent observations by biologists from Texas Parks and Wildlife Department (TPWD) and our lab at CCU suggest that this is not the case. For example, we recently observed brown stains, which were visible to the naked eye, that corresponded with the locations of OTC marks in calcified structures from Tarpon (Megalops atlanticus). Similarly, TPWD biologists observed this phenomenon in Alligator Gar (Atractosteus spatula). These observations are interesting given they occurred independently and in species that are not closely related. From an applied fisheries science perspective, these observations are both concerning and encouraging. First, they are concerning because during the long history of OTC use, OTC marks may have been mistakenly identified as natural marks when viewed without fluorescence filters. However, if these marks consistently form in certain calcified tissues, it will provide a method for marking fish without the need for an often expensive epifluorescent microscope. In collaboration with scientists from the TPWD Heart of the Hills Fisheries Science Center (David Buckmeier, Nate Smith) we are conducting a multi-species experiment to investigate the formation of OTC marks in calcified tissues of freshwater fishes. We will investigate the effects of body size, season, structure (tissue), and species on formation of OTC marks that are visible in calcified tissues with and without fluorescence filters. An added benefit of our experimental design is that it will also provide the opportunity to validate if growth increments form annually in calcified tissues for the species of focus, and therefore be used to estimate age from the calcified structures examined.
Age, growth, and abundance of Muskellunge in the French Broad River, North Carolina
Knowing the number of fish in a population is important for evaluating stocking practices, relating abundance to angler success, and understanding population response to management actions or biotic and abiotic changes to an aquatic ecosystem (e.g., invasive species, development in the watershed). Similarly, age estimation is an important component of fish ecology and management because age data are used to estimate population characteristics such as age-at-maturity, longevity, annual mortality, and growth. Despite, the growing popularity of angling for Muskellunge in the southern portion of their distribution, Muskellunge abundance, age, and growth estimates for waters outside the upper Midwest are rare and are even rarer for riverine populations. The North Carolina Wildlife Resources Commission (Scott Loftis, Amanda Bushon) are leading a 5-year study to better understand population characteristics of Muskellunge in the French Broad River, which is at the southern limit of the Muskellunge's native distribution. At CCU, we are conducting the age estimation and growth and abundance modeling components of this project. Results from this study will allow for a greater understanding of the population biology of Muskellunge in the southern portion of their distribution and complement concurrent Muskellunge focused research in VA, MD, and WV.