Tracy L. Galarowicz

Differences in Growth, Consumption, and Metabolism among Walleyes from Different Latitudes

Abstract Physiological responses to environmental factors such as temperature can vary between stocks of the same species and may be linked to differences in latitude. To determine whether physiological differences exist among populations of young-of-year walleye Stizostedion vitreum as a function of geographic origin, we compared the metabolic rates, food consumption, relative growth, and conversion efficiency among walleyes from Arkansas, Missouri, Wisconsin, and Alberta, Canada, over a range of temperatures (5–25°C). Few or no differences were observed in metabolic rate (mg O2 · g−1 · h−1) among populations at the cooler temperatures, but walleyes from the Arkansas River, Arkansas, had higher rates than the northern populations at warmer temperatures. Both Arkansas populations also had greater food consumption rates (g · g−1 · d−1) than the northern populations at 25°C. However, growth (g · g−1 · d−1) was similar among stocks within each temperature. Our experiments indicate that physiological differen...

Lake Whitefish Relative Abundance, Length-at-Age, and Condition in Lake Michigan as Indicated by Fishery-independent Surveys

ABSTRACT In the mid 1990s, growth and condition of lake whitefish (Coregonus clupeaformis) declined within commercial catches in Lake Michigan. However, underlying mechanisms responsible for the declines have not been thoroughly explored. Using fishery-independent survey data, we examined growth and relative abundance of adult whitefish over historical (1980–1990) and recent (1996–2005) time periods in three regions of Lake Michigan: north, mid, and south. Relative abundance was assessed from catch-per-unit-effort (CPUE) of independent surveys, and changes in growth conditions were evaluated using size-at-age estimates. Relative abundance increased in the mid and south regions between the two time periods and decreased in the north region. Length-at-age significantly declined between the two time periods in the north, mid, and south regions; the north region consistently had the lowest length-at-age. Condition also declined between the two time periods in each region. The decline in growth and condition coupled with increases in relative abundance suggest density-dependent mechanisms are contributing to the observed population changes in the south region. The north region does not appear to be regulated by density, suggesting density-independent mechanisms, such as food web changes, are influencing stocks. Changes in the mid region are likely from a mixture of increased lake whitefish abundance and food web changes. Using fishery-independent population data, our results suggest that multiple factors are potentially contributing differentially within three Lake Michigan regions to cause similar declines in length-at-age and condition of whitefish. These factors (e.g., food web changes, lake whitefish density) should be considered when managing the commercial fishery.

Fish Passage through Culverts in Central Michigan Warmwater Streams

Abstract Road culverts can alter stream flow, remove fish habitat, and limit fish movement. Little is known about the effects of culverts on fish movement in low-order, low-gradient streams in an agricultural setting. Eleven sites on first- and second-order streams in central Michigan were examined for the effects of culvert type (box, bottomless box, pipe arch, and bottomless pipe arch) on fish passage in an agricultural setting. The selected culverts were not obvious barriers to fish passage as none were perched above the stream. Four reaches (two upstream and two downstream of a culvert) were sampled three times in spring, summer, and fall 2011 at each site. Mark–recapture sampling was used to observe fish movement, and the probability of fewer fish being found upstream of a culvert relative to downstream was modeled with logistic regression. Based on recapture movements, limited passage was assumed for at least one fish species during each season at a pipe arch culvert and for one species during summe...

Fish Assemblage Shifts and Population Dynamics of Smallmouth Bass in the Beaver Archipelago, Northern Lake Michigan: A Comparison between Historical and Recent Time Periods amidst Ecosystem Changes

Abstract The ecological and economic importance of Great Lakes nearshore areas and the paucity of information on nearshore Lake Michigan fish assemblages prompted us to document changes that occurred from a historical time period (1969–1972, 1975, 1977, and 1984) to a recent period (2005–2008) in a nearshore northern Lake Michigan (Beaver Archipelago) fish assemblage, with an emphasis on smallmouth bass Micropterus dolomieu. From historical to recent periods, the Beaver Archipelago fish assemblage shifted from predominantly brown bullheads Ameiurus nebulosus to predominantly smallmouth bass. Relative abundance of brown bullheads and white suckers Catostomus commersonii declined from historical to recent time periods, as did overall species richness. The relative abundance, recruitment variability, and mortality rates of smallmouth bass have not significantly changed since the historical time period, whereas both condition (ages 5–7) and growth (ages 2–7) of this species have significantly increased. Our r...

A Comparison of Egg Funnel and Egg Bag Estimates of Egg Deposition in Grand Traverse Bay, Lake Michigan

Abstract Reefs are used for spawning by Great Lakes fishes such as the lake trout Salvelinus namaycush, lake whitefish Coregonus clupeaformis, and cisco C. artedi. We designed egg funnels as a new type of sampling gear for quantifying egg deposition while minimizing losses of eggs to physical disturbance and predation. Egg funnels were compared with traditionally used egg bags to quantify egg deposition by spawning fish. In addition, the efficiencies of the egg funnels and egg bags were measured by seeding each gear type with artificial lake trout and lake whitefish eggs in situ. Egg funnels were as efficient as or more efficient than egg bags for capturing artificial eggs and naturally deposited lake trout eggs in both 2008 and 2009. Egg funnels had lower efficiency than egg bags for capture of natural coregonid eggs in 2008, potentially due to avoidance of the gear by spawners; gear avoidance was reduced by burying the egg funnels more deeply in 2009. Accurate estimates of egg deposition will assist fis...

Summer Habitat Use by Lake Sturgeon in Manistee Lake, Michigan

Abstract The Lake Sturgeon Acipenser fulvescens is targeted for rehabilitation across its range, but little is known about habitat use by Lake Sturgeon during periods other than the spawning period. Insight into habitat use during nonspawning periods for these long-lived fish is crucial to our understanding of this species and its recovery. Our goal was to characterize summer habitat use by Lake Sturgeon in Manistee Lake, Michigan, a drowned river mouth complex. Fish were tagged and relocated in the lake by using telemetry in 2003–2005. The lake was divided into 18 sampling sections, and abiotic and biotic variables with potential influences on habitat use were quantified in each section during May–July in 2003 and 2004. Lake Sturgeon were found in the lake during May–July and primarily occupied habitats near the wetland complex and shipping channel in the northern portion of the lake. Water depth, temperature, dissolved oxygen level, Secchi depth, and densities of chironomid larvae, dreissenid mussels, b...

Predictors of Walleye Growth and Survival in Michigan Hatchery Ponds

Abstract Walleyes Sander vitreus are extensively cultured across Michigan, with highly variable success resulting in substantial differences in growth and survival. The present study was undertaken in 2005 and 2006 to determine the relationship between abiotic components (temperature, dissolved oxygen, and nutrient levels), prey (zooplankton and benthic macroinvertebrate) availability, and stocking density in ponds in the Lower Peninsula of Michigan and the growth and survival of walleyes in these ponds. Besides fertilization of some of the ponds, there was no management of the ponds until harvest. Ponds were grouped by similarity of abiotic and biotic factors. Correlations among walleye length, weight, and stocking density, as well as between walleye percent survival and stocking density, provided contradictory results between years. Walleye growth and survival were correlated with planktonic prey densities and nutrient levels. Although these interactions among abiotic variables, prey availability, and w...