The University of Toledo

About the GLGL

The first emphasis of GLGL addresses one of the most pertinent issues in fisheries management – which is the identification of genetically meaningful management units, i.e., stocks. Fishery stocks (also known as population units) represent unique breeding groups that often possess novel forms of genetic, physiological, and ecological variation. Genetic diversity may enable a species to withstand environmental perturbations, such as fishing pressure, habitat degradation, and competition from invading species – all of which pose serious issues in the Great Lakes. Preserving genetic variation is believed to be fundamental for enabling a species to adapt to changing and existing environments, and is a key goal for conservation management.

GLGL has focused on developing high-resolution DNA markers to distinguish fishery stocks for the three species regarded as the most economically important by managers in the lower Great Lakes – walleye, yellow perch, and smallmouth bass. GLGL works closely with Lake Erie fishery managers, including Ohio, Pennsylvania, New York, Illinois, Michigan, Minnesota, Winconsin, and Ontario, and well as the U.S. Fish and Wildlife Service, the Great Lakes Fishery Commission, and NOAA. The specific outcome of the ongoing collaborative work with fishery agencies has been the implementation of microsatellite DNA markers and nuclear and mitochondrial DNA sequence data coupled with high-resolution statistical analyses in a rapid-throughput protocol to analyze stock structure of exploited fishes in the Great Lakes. Dr. Stepien has been funded for these efforts for walleye, yellow perch, and smallmouth bass stock structure from the NOAA Sea Grant program and the USEPA.

The GLGL genetic data sets for walleye, yellow perch, and smallmouth bass reveal that spawning stocks in given areas house unique genetic variability. Fishery managers and scientists recognize that management and policy needs to preserve this genetic diversity for maintenance of the overall lake populations, in the face of climatic variability, pollution, habitat degradation, and exploitation. As a result of these ongoing efforts and communication of our results, Lake Erie and other Great Lakes fishery managers are increasingly using the GLGL lab genetic data to develop “bag” and seasonal limits for exploitation of fishery stocks. For example, these genetic data for the smallmouth bass populations in Lake Erie led to a new 2004 spring spawning season moratorium on fishing. Great Lakes agency fishery management goals at the federal and state levels increasingly recognize the need to evaluate genetic data of stocks as a critical management tool, in which the GLGL lab has played a vital role.

The second GLGL research emphasis involves using DNA sequence data to address the problem of nonindigenous species invasions in the Great Lakes. Ecologists today regard nonindigenous species introductions as one of the most serious threats to our worldwide native ecosystems. The ecology of the North American Great Lakes has been restructured by waves of invaders that were accidentally introduced from ships’ ballast water – including the zebra and quagga mussels, the ruffe fish, and the round and tubenose gobies being investigated by GLGL. The genetic character of an introduced population is believed to be fundamental to its invasive success, and also provides important data that can be used for comparative environmental risk analysis and management assessment.

The genetic composition of an invasive population is determined by the number, genetic diversity, and sources of its founding propagules, as well as stochastic and selective factors that determine the survival and reproduction of given genotypes in the new environment. GLGL research uses genetic data to evaluate the number, geographic areas, and vectors of source populations for exotic species invasions (including dreissenid mussels, gobies, and ruffe fish), to interpret whether new colonization areas are the result of spread or new introductions, and to determine whether genetic changes occur over the time course of invasions. Research results are being used by management agencies, including the Aquatic Nuisance Species International Task Force, to develop policy for preventing ballast water introductions and circumventing spread of nonindigenous populations.

GLGL research on zebra and quagga mussel genetics, as well as the round goby invasion; involving comparisons between potential Eurasian founding source areas and areas of their invasion in the Great Lakes, have indicated considerable genetic diversity – comparable to that of native populations. Matches with Eurasian populations suggest that there have been a number of independent introductions of zebra and quagga mussels and round gobies in North America. These results indicate a serious management control problem, as the new populations show little “founder effect” and their high genetic diversity may provide resilience in adapting to new environments, fueling the success of these invasions. Our research by GLGL on nonindigenous species invasions has been funded by awards to Dr. Stepien from the National Science Foundation, the USEPA, and the Lake Erie Protection Fund.