Charles P. Madenjian
B.S. (Aquatic Biology), Rutgers University, 1975
M.S. (Resource Ecology), University of Michigan, 1979
Ph.D. (Zoology), University of Hawaii, 1988
Since it became a lakewide survey in 1973 (i.e., sampling 7 transects consistently: Manistique, MI; Frankfort, MI; Ludington, MI; Saugatuck, MI; Waukegan, IL; Port Washington, WI; Sturgeon Bay, WI) the Lake Michigan bottom trawl study has played a critical role in understanding the ecosystem dynamics and in managing the fisheries of Lake Michigan. Its primary role is to provide annual estimates of prey fish abundance to guide the decision of state agencies in the stocking of piscivorous fish. Beyond these data, GLSC researchers have analyzed the time series to 1) further understanding of the factors that regulate the recruitment of alewife, bloater, deepwater sculpin, and slimy sculpin, 2) determine trends in the growth, maturation, and condition of alewife and bloater, and 3) conduct community analyses to explore how the prey fish community has responded to invasive species, such as alewife and dreissenid mussels. Maintenance of this long-term data set is critical to provide a benchmark for how these important fishes are responding to the persistent perturbations to the Lake Michigan ecosystem, include invasive species and climate change.
The burbot recovery in Lake Michigan coincided with a decline in the abundance of deepwater sculpin (Myoxocephalus thompsonii). As burbot abundance leveled off during the 1990s, so too did deepwater sculpin abundance. Thus, the Great Lakes Science Center bottom trawl survey data suggested a predator-prey link between the burbot and deepwater sculpin populations. However, bioenergetics modeling has not been applied to the burbot population in Lake Michigan to estimate annual consumption of deepwater sculpins by burbot. In addition, the round goby (Neogobius melanostomus) is slowly spreading into the main basin of Lake Michigan. Bioenergetics model applications to the burbot population would be useful in estimating annual consumption of round gobies by burbot. In this way, the role of burbot within the Lake Michigan food web becomes better defined.
Specifically, the objectives of this study are to: (1) compare diet, growth, maturity, fecundity, thiamine levels in eggs, annual survival, and sea lamprey mortality of lake trout at various stocking sites in Lake Michigan, (2) compare growth and survival of various strains of lake trout stocked into Lake Michigan, (3) use the above-mentioned research findings to improve the lake trout rehabilitation effort in Lake Michigan, (4) survey the lake trout population in Lake Michigan for evidence of natural reproduction, (5) use the results of this surveillance for management recommendations concerning lake trout rehabilitation in Lake Michigan, (6) use the spring LWAP survey results to characterize the population dynamics of burbot in Lake Michigan, and (7) apply bioenergetics modeling to the burbot population to estimate annual consumption of various prey fishes.
Despite frequent application, fish bioenergetics models have several limitations at present. First, more evaluations of model performance are needed to identify conditions under which model performance is poor. During the past 10 to 15 years, efforts have been made to evaluate fish bioenergetics model performance in the laboratory and the field. But, substantially more effort is needed to fully evaluate the suite of available fish bioenergetics models. In addition, fish bioenergetics models are still unavailable for many species of fish. Second, the fish bioenergetics software contains "bugs" and is out of date. Certainly, there is a need to correct the errors in the software and to modernize the software approach, while still allowing the software to be easily applied by users. Third, the current versions of the fish bioenergetics models have no resolution with regard to sex-specific activity or sex-specific resting metabolic rates (standard metabolic rates or SMRs). Yet, results from contaminant survey work, as well as results from the few telemetry studies, have indicated that adult male fish are more active than adult female fish and that resting metabolic rate is higher in adult males than in adult females. The objectives of this study are to address the aforementioned limitations of fish bioenergetics modeling.