Publications

Eleven male walleyes (Sander vitreus) and 10 female walleyes from the Saginaw Bay (Lake Huron) population were caught during the spawning run at Dow Dam (Midland, Michigan) in the Tittabawassee River during April 1996, and individual whole-fish polychlorinated biphenyl (PCB) determinations were made. Total PCB concentrations averaged 7.95 and 3.17??mg/kg for males and females...

We examined the feeding ecology of larval lake whitefish (Coregonus clupeaformis) in Chaumont Bay, Lake Ontario, during April and May 2004-2006. Larvae were collected with towed ichthyoplankton nets offshore and with larval seines along the shoreline. Larval feeding periodicity was examined from collections made at 4-h intervals over one 24-h period in 2005. Inter-annual variation in...

Throughout much of the Great Lakes basin, reproduction of several fish species is impaired by deficiency of thiamine in their eggs, an effect attributed to consumption of thiaminase-containing forage species, primarily alewife (Alosa pseudoharengus.) Because the double-crested cormorant (Phalacrocorax auritus) nesting on islands in Lake Ontario is known to consume considerable amounts of...

Growth and survival of stocked Sander spp. fingerlings can be influenced by timing of stocking in relation to the peak in density of larval gizzard shad Dorosoma cepedianum. However, coordinating stockings to coincide with peaks in gizzard shad density is difficult due to temporal variation in spawn timing among reservoirs. We used weekly estimates of larval gizzard shad density and...

The U.S.Geological Survey Great Lakes Science Center has conducted trawl surveys to assess annual changes in the deepwater demersal fish community of Lake Huron since 1973. Since 1992, surveys have been carried out using a 21 m wing trawl towed on-contour at depths ranging from 9 to 110 m on fixed transects. Sample sites include five ports in U.S. waters with less frequent sampling near...

The Great Lakes Science Center (GLSC) has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size structure, and condition of individual fishes are used to estimate various population parameters that...

Spatial patterns in the biomass of pelagic fish in Lake Huron have persisted over 10 years even though biomass decreased 86% and the fish community shifted from dominance by non-native species (rainbow smelt, Osmerus mordax) to dominance by native species (bloater, Coregonus hoyi). Based on multivariate analyses of acoustic biomass data and abiotic variables from the years 1997, 2004...

Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2008 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. In 2005, we began sampling Mysis...

The opossum shrimp Mysis diluviana (formerly M. relicta) performs large amplitude diel vertical migrations in Lake Ontario and its nighttime distribution is influenced by temperature, light and the distribution of its predators and prey. At one location in southeastern Lake Ontario, we measured the vertical distribution of mysids, mysid predators (i.e. planktivorous fishes) and mysid...

Two issues in ecological network theory are: (1) how to construct an ecological network model and (2) how do entire networks (as opposed to individual species) adapt to changing conditions? We present a novel method for constructing an ecological network model for the food web of southeastern Lake Michigan (USA) and we identify changes in key system properties that are large relative to...

Human activities have affected the Lake Huron ecosystem, in part, through alterations in the structure and function of its food webs. Insights into the nature of food web change and its ecological ramifications can be obtained through the monitoring of high trophic level predators such as aquatic birds. Often, food web change involves alterations in the relative abundance of constituent...

The Great Lakes Science Center of the United States Geological Survey (USGS) is working cooperatively with the Ontario Ministry of Natural Resources (OMNR) on a threeyear study to develop standard procedures for acoustic and midwater trawl (AC-MT) assessments of spawning cisco Coregonus artedi that the OMNR can carry forward as a management activity. In year two (2008), we conducted an...