Publications

The morphology of pharyngeal teeth of freshwater drum (Aplodinotus grunniens) was studied to determine changes that occur during growth of drum that may relate to consumption of zebra mussel (Dreissena polymorpha) by larger fish. Pharyngeal teeth were of three types. Cardiform teeth were replaced by villiform teeth, which were replaced by molariform teeth as the size class of drum...

Various studies indicate that PCBs appear to have an adverse effect on the viability of fertilized eggs and subsequent early life stages of lake trout and related species. Our tests detected no impairment of fertilization of lake trout eggs in PCB-dosed lake water. The concentration of PCBs in the fertilization medium that we used was more than 20 times as high as estimated ambient...

A revised annotated checklist for the chironomid midges (Diptera: Chironomidae) of the southeastern United States is presented that includes the states of Alabama, Florida, Georgia, North Carolina, South Carolina, and Tennessee. Much of the information concerns occurrence and habitat preference records based upon the authors' data, as well as published and unpublished data. Some...

The restoration of lake trout Salvelinus namaycush in Lake Michigan has been an elusive goal of resource management agencies in the Great Lakes region. In this study, we estimated annual survival rates of adult lake trout from an area in northwestern Lake Michigan known as the Clay Banks refuge. We tagged and recaptured fish with gill nets during the fall spawning season (N = 12,175...

Ruffe (Gymnocephalus cernuus) occur widely in Eurasia. This species was accidentally introduced into Lake Superior and rapidly occupied the western part of the lake. Ruffe had a strong impact on populations of commercially important fish species and on commercial fishing. Our studies show that ruffe from Lake Superior are strongly infested by parasites specific to North America. These

The present study was conducted to determine impacts of zebra mussel [Dreissena polymorpha (Pallas, 1771); Dreissenidae] infestation on unionids in firm substrata in western Lake Erie. Unionid mollusks were collected at a total of 15 stations on three offshore depth contours (2, 3, and 4 m) in 1983 (before zebra mussel infestation), in 1990 and 1993 (after zebra mussel infestation), and...

Restrictions on the release of PCBs into the environment began in the early 1970s, resulting in reduced PCB concentrations in Lake Michigan bloaters (Coregonus hoyi). However, since 1980, PCB concentrations in bloater have declined only slightly. The bloater population also increased 40-fold during 1970 through 1984, resulting in a diet shift and a density-dependent decline in growth...

The bloater (Coregonus hoyi), which feeds mainly on invertebrates and in turn is eaten by lake trout (Salvelinus namaycush) and burbot (Lota lota), is a major trophic integrator in coldwater ecosystems in the upper Great Lakes. To better understand their thermal niche and habitat distribution, we acclimated groups of yearling bloater to 3, 5, 10, 15, 20, or 25°C and then fed them ad...

Little is known about the stock structure of lake herring Coregonus artedi in Lake Superior, and recent increases in harvestable stock sizes has led to expanded exploitation in some areas. Research on marine teleosts has demonstrated that chemical differences in sagittal otoliths can be used for identification of fish stocks. We used plasma emission spectrophotometry to measure the...

Exotic zebra mussels Dreissena polymorpha have infested and caused mortality of native unionids in the Great Lakes since 1986; no other such parasitism of native unionids occurs in North America. Survival of unionids threatened by zebra mussel infestation was tested by suspending uncleaned and cleaned unionids in nearshore waters of western Lake Erie. Survival was determined, and newly...

The ruffe Gymnocephalus cernuus is a European percid that was accidently introduced in Duluth Harbor, Lake Superior. This nonindigenous species is closely related to yellow perch Perca flavescens, and because the two species have similar diets and habitat requirements, they are potential competitors. Laboratory studies in aquaria and pools were conducted to determine whether ruffe can...

The reproductive cycle of the zebra mussel {Dreissena polymorpha) is highly variable throughout its range in Europe, Russia, and North America. The environmental factors influencing this variation are poorly understood, but successful reproduction is occurring in areas where it was initially believed that adult zebra mussels could not survive (i.e., southern United States). The...