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Marquette, MI, United States

Grossman G.D.,University of Georgia | Nuhfer A.,Hunt Creek Fisheries Research Station | Zorn T.,Marquette Fisheries Research Station | Sundin G.,University of Georgia | Alexander G.,Hunt Creek Fisheries Research Station
Freshwater Biology | Year: 2012

Fisheries models generally are based on the concept that strong density dependence exists in fish populations. Nonetheless, there are few examples of long-term density dependence in fish populations. Using an information theoretical approach (AIC) with regression analyses, we examined the explanatory power of density dependence, flow and water temperature on the per capita rate of change and growth (annual mean total length) for the whole population, adults, 1+ and young-of-the-year (YOY) brook trout (Salvelinus fontinalis) in Hunt Creek, Michigan, USA, between 1951 and 2001. This time series represents one of the longest quantitative population data sets for fishes. Our analysis included four data sets: (i) Pooled (1951-2001), (ii) Fished (1951-65), (iii) Unfished (1966-2001) and (iv) Temperature (1982-2001). Principle component analyses of winter flow data identified a gradient between years with high mean daily winter flows, high daily maximum and minimum flows and frequent high flow events, and years with an opposite set of flow characteristics. Flows were lower during the Fished Period than during the Unfished Period. Winter temperature analyses elucidated a gradient between warm mean, warm minimum and maximum daily stream temperatures and a high number of minimum daily temperatures >6.1°C, and years with the opposite characteristics. Summer temperature analyses contrasted years with warm summer stream temperatures vs years with cool summer stream temperatures. Both YOY and adult densities varied several-fold during the study. Regression analysis did not detect a significant linear or nonlinear stock-recruitment relationship. AIC analysis indicated that density dependence was present in 15 of 16 cases (four population segments×four data sets) for both per capita rate of increase (w i values 0.46-1.00) and growth data (w i values 0.28-0.99). The almost ubiquitous presence of density dependence in both population and growth data is concordant with results from other trout populations and other studies in Michigan. © 2012 Blackwell Publishing Ltd. Source

Zorn T.G.,Marquette Fisheries Research Station
North American Journal of Aquaculture | Year: 2015

Abstract: The effectiveness of stocking hatchery-reared Walleyes Sander vitreus to supplement native populations in large, open systems like the Great Lakes has not been thoroughly evaluated. I quantified recent contributions of stocked Walleye fingerlings to populations in Little Bay de Noc (LBDN) and Big Bay de Noc (BBDN) in northern Green Bay, Lake Michigan. Oxytetracycline-marked Walleye fingerlings were stocked in June, and late summer gill-net and night-time boat electrofishing surveys were used to index Walleye year-class abundance and collect juvenile Walleyes for hatchery mark evaluation. For the 2004–2009 year-classes, 76% of the age-0 to age-3 Walleyes examined from LBDN were of wild origin and 62% in BBDN were naturally reproduced fish. Survey catch rates of juvenile Walleyes were similar for stocked and nonstocked year-classes. Assessment catch rates of age-1 and age-2 Walleyes differed significantly by location, with average catch rates in LBDN often being ten times higher than those in BBDN. Age-0 Walleyes persisted to older ages and were well-represented at numerous sampling locations in LBDN, but few age-1 and older Walleyes were caught in BBDN. The differences in growth between hatchery-reared and wild Walleyes were minor compared with the differences between bays. Based on stocking records and creel estimates available since 1985, the harvest rate of Walleyes was not significantly correlated to the numbers of Walleyes stocked 4–6 years earlier in LBDN or BBDN. Despite low stocking rates, stocked fish likely provided some contribution (though not a statistically significant one) to Walleye year-classes and the sport fishery in LBDN, but their contribution in BBDN was less apparent. Managers should weigh the trade-offs of supplemental stocking in Great Lakes waters when considering requests for hatchery Walleyes in smaller lakes and rivers, especially when stocking resources are limited. Received February 20, 2014; accepted April 17, 2015 © 2015, © American Fisheries Society 2015. Source

Gorman O.T.,U.S. Geological Survey | Sitar S.P.,Marquette Fisheries Research Station
Transactions of the American Fisheries Society | Year: 2013

The fish community of Lake Superior has undergone a spectacular cycle of decline and recovery over the past 60 years. A combination of Sea Lamprey Petromyzon marinus depredation and commercial overfishing resulted in severe declines in Lake Trout Salvelinus namaycush, which served as the primary top predator of the community. Burbot Lota lota populations also declined as a result of Sea Lamprey depredation, largely owing to the loss of adult fish. After Sea Lamprey control measures were instituted in the early 1960s, Burbot populations rebounded rapidly but Lake Trout populations recovered more slowly and recovery was not fully evident until the mid-1980s. As Lake Trout populations recovered, Burbot populations began to decline, and predation on small Burbot was identified as the most likely cause. By 2000, Burbot densities had dropped below their nadir in the early 1960s and have continued to decline, with the densities of juveniles and small adults falling below that of large adults. Although Burbot populations are at record lows in Lake Superior, the density of large reproductive adults remains stable and a large reserve of adult Burbot is present in deep offshore waters. The combination of the Burbot's early maturation, long life span, and high fecundity provides the species with the resiliency to remain a viable member of the Lake Superior fish community into the foreseeable future. Received October 1, 2012; accepted July 9, 2013. © 2013 Copyright Taylor and Francis Group, LLC. Source

Zorn T.G.,Marquette Fisheries Research Station | Wills T.C.,Lake St Clair Fisheries Research Station
North American Journal of Fisheries Management | Year: 2012

Excess sand bedload can significantly degrade salmonid habitat and populations. Successful use of sediment traps to restore habitat and salmonid populations on two Michigan streams in the early 1980s led to application of traps at well over 100 coldwater streams in Michigan and rivers throughout the USA within a decade. Unfortunately, little quantitative evaluation has occurred other than anecdotal observations for some traps. We conducted a broad-scale survey of 65 Michigan stream reaches with sediment traps by collecting data along transects upstream and downstream of the traps to assess downstream changes in substrate composition, channel depth, and channel stability in response to sediment traps. We found that recent applications of sediment traps (usually as stand-alone instream habitat treatments) had no significant effect on substrate, thalweg depth, or bank stability conditions in the reaches studied. Using reach-based estimates of specific stream power at the 10% annual exceedence flow, we identified areas where sediment traps could potentially destabilize channels. Specific stream power estimates were positively correlated with the preponderance of gravel and coarser substrate in stream reaches. Our study and previous assessments of sediment traps suggest that managers carefully consider their river and all potential management options when deciding if sediment traps will provide the best return on their investment. © American Fisheries Society 2012. Source

Forsythe P.S.,Michigan State University | Scribner K.T.,Michigan State University | Crossman J.A.,Michigan State University | Crossman J.A.,BC Hydro | And 4 more authors.
Journal of Fish Biology | Year: 2012

The associations were quantified between daily and interannual variation in the timing of a closed population of lake sturgeon Acipenser fulvescens migration and arrival at spawning sites with stream environmental and lunar covariates. Spawning data were gathered from 1262 fish in Black Lake, Michigan 2001 to 2008 and by video monitoring 2000 to 2002. Sex-specific variation in responses to external cues was also tested. Results showed that a greater number of individuals initiated migration from lake to riverine habitats at dawn and dusk relative to other times of the day. Current and lagged effects of water temperature and river discharge, and periods in the lunar cycle were important variables in models quantifying movements into the river and timing of adult arrival at spawning sites. Different suites of covariates were predictive of A. fulverscens responses during different periods of the spawning season. The timing of initiation of migration and spawning, and the importance of covariates to the timing of these events, did not differ between sexes. Stream flow and temperature covaried with other variables including day length and the lunar cycle. Anthropogenic disruption of relationships among variables may mean that environmental cues may no longer reliably convey information for Acipenseriformes and other migratory fishes. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles. Source

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