Photos of Rubenstein School Professor Ellen Marsden almost invariably show her on the School’s research vessel on Lake Champlain and surrounded by captivated college students as she points out a lesson found in a freshly gutted fish. Some observers might be a tad revolted, but to students in the Rubenstein School Wildlife and Fisheries Biology program, field labs with Professor Marsden are some of the highlights of their time at UVM.
Ellen’s quick wit, easy laugh, and excitement about fish are infectious. Each year, students eagerly await her Fisheries Biology and Techniques course field labs. They literally “get their feet wet” while seine netting and electroshocking fish to sample, measure, and release.
“I considered Ellen one of my best professors as an undergraduate in Rubenstein,” stated current graduate student Lee Simard (WFB ’12), “a feeling that I know was shared by nearly all of my classmates who had her as a professor as well. Ellen is a very engaging speaker and can present difficult material in multiple ways so that everyone understands. Lectures were always exciting and she always ensured everyone took part during labs.”
Ellen has taught fisheries courses in the University of Vermont Rubenstein School and conducted research on Lake Champlain fisheries since 1996. In years prior, she studied Great Lakes fisheries as a scientist at the Lake Michigan Biological Station and as a graduate student at Cornell University.
On board the UVM research vessel Melosira, Ellen’s students learn fish collection methods and hold netted fish before releasing them back to Lake Champlain. In her indoor labs, they learn to identify species of fish, how to measure otoliths, or “ear bones” used to determine fish age and growth rate, and what to do with the measurements and data as fisheries biologists.
“It’s important for students who are training to be fisheries biologists and managers, to have hands-on experiences and to learn traditional and current techniques used in fisheries management,” stated Ellen.
Her students meet state of Vermont fisheries biologists and use state fisheries datasets in her course laboratories. She brings real world examples and current issues in fisheries into her classroom. She also teaches courses in Fisheries Management and in Ichthyology, the study of fish taxonomy, anatomy, behavior, and ecology.
As director of the Wildlife and Fisheries Biology program, Ellen and her colleagues, Associate Professors Allan Strong, Jason Stockwell, and Jed Murdoch, train students in the program with professional skills that prepare them to apply to graduate school.
“We encourage our undergraduates to pursue advanced degrees. Wildlife and fisheries are highly graduate education driven fields,” said Ellen.
Her teaching and research are closely melded by the content she pulls from her own current research projects on Lake Champlain, Lake Huron, and Yellowstone Lake to inject in her lectures and by the many undergraduate and graduate students who work with and learn from her on research projects.
"Ellen is the perfect combination of hands on and hands off,” said her former graduate student Victoria Pinheiro (MS-NR ’15). “She gives you the academic freedom and independence you need to think critically and develop as a researcher, but if you need her she is happy to jump in and provide excellent guidance at any point. I really couldn't imagine studying under anyone else."
Learning about lake trout
Ellen keeps close tabs on fisheries in Vermont’s Lake Champlain. She collaborates with state fisheries biologists and the U.S. Fish and Wildlife Service to study the health of lake trout, an important game fish in the Lake. For many years, she studied invasive sea lamprey and the effects of their parasitism on the declining health of fish populations.
She has since turned her attention to another non-native, invasive species in the lake, the alewife, which made its appearance in the early 2000s. Alewife pose a new threat to native lake trout and Atlantic salmon, already diminished in health and population numbers.
A type of herring, alewife contain thiaminase, an enzyme that breaks down thiamine, or vitamin B1, in its predators, most notably lake trout and Atlantic salmon. A diet of alewife does not provide enough thiamine to trout and salmon eggs, resulting in weak fry, or young. Severe thiamine deficiency in hatchery lake trout fry, used to replenish Lake populations, began causing physical and behavioral symptoms and high rates of mortality in 2008.
Ellen and her former graduate student Bret Ladago (MS-NR ‘13) examined whether early foraging in wild lake trout fry could restore thiamine. They found that in the wild, as opposed to in a hatchery, fry begin eating on their own within a week. Current graduate student Carrie Kozel is conducting experiments to determine whether this early feeding does, in fact, replenish low thiamine levels. Hatcheries can cure thiamine deficiency problems by dosing fry with thiamine.
With Associate Professor Jason Stockwell, former graduate student Tori Pinheiro, and Great Lakes colleagues, Ellen also studies lake trout spawning behavior – how they select mates, how behavior changes from daytime to nighttime, when spawning occurs, and whether males and females differ in their movement among spawning sites. The team tags lake trout in Lake Champlain with tiny transmitters and uses a technique called acoustic telemetry to follow trout movements year-round, throughout the lake. They also observe behavior on spawning reefs using a handmade, remotely-operated vehicle, and most recently they are using an infra-red camera to record nocturnal spawning of lake trout.
In addition to working with these cutting-edge technologies, the team recently made an astonishing find the old-fashioned way. While trawling with a net in Lake Champlain, they discovered an abundance of naturally produced lake trout juveniles for the first time since stocking began in the 1970s.
“Lake trout were disappearing at four weeks of age,” said Ellen, “but we couldn’t understand why because we couldn’t find them. A subtle shift in the food web may have occurred, and they may now be able to find the right food. It is really encouraging to see.”
The U.S. National Park Service called upon Ellen’s expertise to tackle just the opposite problem with lake trout in Yellowstone National Park where lake trout were introduced to Yellowstone Lake in the 1980s and 90s. The non-native species now threatens native cutthroat trout, but National Park Service attempts to catch adult and juvenile lake trout to reduce populations have proved unsuccessful.
Ellen and graduate student Lee Simard are working on suppression of lake trout eggs and fry instead. To assess the feasibility of suppressing these early life stages, they investigate where in Yellowstone Lake the lake trout spawn, their hatching success, and factors that affect survival of eggs and fry to use against them in suppression of the species.
Lee’s research experience with Ellen is just what he hoped for when he returned to the Rubenstein School.
“As a graduate advisor, Ellen challenges me to develop my own research questions and sampling plans, but also provides guidance and assistance whenever I need it,” stated Lee. “Her expertise in fisheries research and management is very apparent when working with her in both lab and field settings. With Ellen’s support behind me, I am confident that my own research is high quality and is important in the field.”
Learning about lake habitat
With yet another graduate student, Peter Euclide, Ellen is studying habitat fragmentation in Lake Champlain. Since the early 1800s, Lake Champlain has been progressively fragmented by causeways that create virtually isolated bays. The effect of these barriers to fish movement is largely unstudied. Ellen and Peter are examining genetic differentiation of several fish species in each bay and estimating the movements of one species, walleye, among basins from telemetry and mark and recapture data.
“We are gaining a better understanding of the effects of these causeways on fish movement and connectivity among basins,” explained Ellen. “The Lake has four major basins that are now cut off from each other. An 80-foot opening in the 3.7-mile Colchester causeway is not much room for fish to move through.”
With colleagues at the Michigan Department of Natural Resources, the U.S. Fish and Wildlife Service, and the National Oceanic and Atmospheric Administration’s Thunder Bay National Marine Sanctuary, Ellen is a team member on a long-term project to restore habitat in Lake Huron’s Thunder Bay. To remediate loss of critical lake trout spawning habitat, the researchers constructed 27 artificial reefs in the bay. The team is conducting a five-year assessment of the factors (reef orientation, height, and size) that attract spawning lake trout and lake whitefish and maximize egg and fry survival to apply to bay restoration.
Awards and aptitudes
A recipient of eight best paper awards from various scientific journals of fisheries and lake research, Ellen is the author of three book chapters and more than 100 peer-reviewed journal articles. She has served as associate editor for the Journal of Great Lakes Research and the North American Journal of Fisheries Management.
Early in her teaching career in the School, she received the 2000 Marcia Caldwell Award for commitment and dedication to the students of the School.
A scuba diver and dive master with numerous certifications, Ellen frequently uses her diving skills in her lake research. She also folk dances with a local troupe in Burlington.