The population dynamics of alewives Alosa pseudoharengus and spottail shiners Notropis hudsonius were investigated in Indiana waters of Lake Michigan from 1984-1996. Insights to population dynamics of both species were found by applying age and growth information to length-frequency distributions of index trawl catches within and between years. Both alewife and spottail shiner populations showed general increasing trends over the period, reaching peak levels in 1996. Interaction potential was examined for alewives, spottail shiners, and the yellow perch Perca flavescens, another important nearshore species. Trends in relative catches of these species were correlated to provide insight to possible interactions. There appears to be negative relationships between alewife and yellow perch populations, as well as between yellow perch and spottail shiner populations. No relationships were found between alewife and spottail shiner populations. / Department of Biology

The fish, invertebrate, and macrophyte communities of Dumpert's Lake, a borrow pit located in northwest Delaware County, Indiana were studied in 1979 and 1980. Data obtained from this study were used to evaluate the potential for quality fishing, to identify sport fish production problems, to assess largemouth bass food habits and habitat utilization, and to consider management options.Bluegill dominated the July and September, 1980 fish collections at 69 and 84 percent, respectively. The growth rates for age II and older bluegill indicated mortality rates above 55 percent. Stocklength (3 in., 76 mm) was.attained at annulus 2 and quality-length (6 in., 152 mm) was reached at age III+. The overall average annual growth increment was 48 mm (1.9 in.). Bluegill were in good condition by overall average K at capture (2.05) and at annulus formation (1.91). Corresponding mean Relative Weight (Wr) values were 106 and 107, respectively.Largemouth bass comprised 23 and 14 percent, respectively, of the July and September, 1980 fish collections. Bass attained stock-length (8 in., 200 mm) by age II+ and an additional 1.5-2.0 years (age III+ or older) was required to attain quality-length (12 in., 300 mm). Growth rates and length-frequency distribution verified mortality rates in excess of 60 percent for all age groups of stock-size bass. Average yearly growth was 70 mm (2.8 in.). Condition was poor by overall average K at capture (1.27) and at annulus formation (1.22). The overall mean Wr was 89 for the respective K values.A stock structure index, Proportional Stock Density (PSD), indicated an unbalanced largemouth bass and bluegill population. Bluegill PSD was 78 with largemouth bass PSD at 27.Radio telemetry observations for two largemouth bass monitored from late May to mid-July, 1980 indicated relative inactivity by observed displacement (98 and 366 m) with respective home ranges of 0.01 and 0.12 ha. Extensive use of shoreline cattails was noted at 79 and 84 percent of the respective locations. All observations were over lake depths of 0.5-0.9 m. Two bass tracked from late July to mid-September, 1980 were more active by displacement (1401 and 1429 m) with home ranges of 0.92 ha for both fish, and similar utilization of submergent pondweeds (46 and 50 percent, respectively). One bass was always observed over lake depths of 1.0 m or greater. The other bass was observed in shallow water (0.5-0.9 m) for 50 percent of the observations.Fish occurred more frequently (71 percent) in stomachs of largemouth bass ranging from 195-247 mm than in stomachs (11 percent) of bass 253-347 mm total length. Insects dominated the diet of the larger fish by percent in volume and weight (66 percent) compared to the smaller stock-size bass (21-22 percent). Odonata was the most frequent insect taxa in the diet of the smaller bass at 29 percent and Ephemeroptera was the dominant insect taxa (33 percent) in the diet of the larger fish.Epifaunal macroinvertebrates were more diverse by taxa compared to macroinvertebrates from three benthic habitats which were about equal in diversity by taxa. Zooplankton diversity by taxa was also similar among the benthic habitats. Macroinvertebrate density showed a trend of seasonal increase for the 1979 summer period, while distinct biomodal peaks for zooplankton abundance occurred in early July and late August, 1979 for vegetated and nonvegetated littoral zones.Najas flexilis, Potamogeton nodosus, and P. pusillus dominated the submergent macrophyte community in 1979. The overall mean seasonal dry weight biomass of macrophytes was 110 g/m2 (114 g/m3 ). Macrophyte control was recommended for improving the sport fishery.Ball State UniversityMuncie, IN 47306